/*
 * JPEG 2000 image decoder
 * Copyright (c) 2007 Kamil Nowosad
 * Copyright (c) 2013 Nicolas Bertrand <nicoinattendu@gmail.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * JPEG 2000 image decoder
 */

#include <inttypes.h>
#include <math.h>

#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/common.h"
#include "libavutil/imgutils.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "avcodec.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "decode.h"
#include "thread.h"
#include "jpeg2000.h"
#include "jpeg2000dsp.h"
#include "profiles.h"
#include "jpeg2000dec.h"
#include "jpeg2000htdec.h"

#define JP2_SIG_TYPE    0x6A502020
#define JP2_SIG_VALUE   0x0D0A870A
#define JP2_CODESTREAM  0x6A703263
#define JP2_HEADER      0x6A703268

#define HAD_COC 0x01
#define HAD_QCC 0x02

// Values of flag for placeholder passes
enum HT_PLHD_STATUS {
    HT_PLHD_OFF,
    HT_PLHD_ON
};

#define HT_MIXED 0x80 // bit 7 of SPcod/SPcoc


/* get_bits functions for JPEG2000 packet bitstream
 * It is a get_bit function with a bit-stuffing routine. If the value of the
 * byte is 0xFF, the next byte includes an extra zero bit stuffed into the MSB.
 * cf. ISO-15444-1:2002 / B.10.1 Bit-stuffing routine */
static int get_bits(Jpeg2000DecoderContext *s, int n)
{
    int res = 0;

    while (--n >= 0) {
        res <<= 1;
        if (s->bit_index == 0) {
            s->bit_index = 7 + (bytestream2_get_byte(&s->g) != 0xFFu);
        }
        s->bit_index--;
        res |= (bytestream2_peek_byte(&s->g) >> s->bit_index) & 1;
    }
    return res;
}

static void jpeg2000_flush(Jpeg2000DecoderContext *s)
{
    if (bytestream2_get_byte(&s->g) == 0xff)
        bytestream2_skip(&s->g, 1);
    s->bit_index = 8;
}

/* decode the value stored in node */
static int tag_tree_decode(Jpeg2000DecoderContext *s, Jpeg2000TgtNode *node,
                           int threshold)
{
    Jpeg2000TgtNode *stack[30];
    int sp = -1, curval = 0;

    if (!node) {
        av_log(s->avctx, AV_LOG_ERROR, "missing node\n");
        return AVERROR_INVALIDDATA;
    }

    while (node && !node->vis) {
        stack[++sp] = node;
        node        = node->parent;
    }

    if (node)
        curval = node->val;
    else
        curval = stack[sp]->val;

    while (curval < threshold && sp >= 0) {
        if (curval < stack[sp]->val)
            curval = stack[sp]->val;
        while (curval < threshold) {
            int ret;
            if ((ret = get_bits(s, 1)) > 0) {
                stack[sp]->vis++;
                break;
            } else if (!ret)
                curval++;
            else
                return ret;
        }
        stack[sp]->val = curval;
        sp--;
    }
    return curval;
}

static int pix_fmt_match(enum AVPixelFormat pix_fmt, int components,
                         int bpc, uint32_t log2_chroma_wh, int pal8)
{
    int match = 1;
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);

    av_assert2(desc);

    if (desc->nb_components != components) {
        return 0;
    }

    switch (components) {
    case 4:
        match = match && desc->comp[3].depth >= bpc &&
                         (log2_chroma_wh >> 14 & 3) == 0 &&
                         (log2_chroma_wh >> 12 & 3) == 0;
    case 3:
        match = match && desc->comp[2].depth >= bpc &&
                         (log2_chroma_wh >> 10 & 3) == desc->log2_chroma_w &&
                         (log2_chroma_wh >>  8 & 3) == desc->log2_chroma_h;
    case 2:
        match = match && desc->comp[1].depth >= bpc &&
                         (log2_chroma_wh >>  6 & 3) == desc->log2_chroma_w &&
                         (log2_chroma_wh >>  4 & 3) == desc->log2_chroma_h;

    case 1:
        match = match && desc->comp[0].depth >= bpc &&
                         (log2_chroma_wh >>  2 & 3) == 0 &&
                         (log2_chroma_wh       & 3) == 0 &&
                         (desc->flags & AV_PIX_FMT_FLAG_PAL) == pal8 * AV_PIX_FMT_FLAG_PAL;
    }
    return match;
}

// pix_fmts with lower bpp have to be listed before
// similar pix_fmts with higher bpp.
#define RGB_PIXEL_FORMATS   AV_PIX_FMT_PAL8,AV_PIX_FMT_RGB24,AV_PIX_FMT_RGBA,AV_PIX_FMT_RGB48,AV_PIX_FMT_RGBA64
#define GRAY_PIXEL_FORMATS  AV_PIX_FMT_GRAY8,AV_PIX_FMT_GRAY8A,AV_PIX_FMT_GRAY16,AV_PIX_FMT_YA16
#define YUV_PIXEL_FORMATS   AV_PIX_FMT_YUV410P,AV_PIX_FMT_YUV411P,AV_PIX_FMT_YUVA420P, \
                            AV_PIX_FMT_YUV420P,AV_PIX_FMT_YUV422P,AV_PIX_FMT_YUVA422P, \
                            AV_PIX_FMT_YUV440P,AV_PIX_FMT_YUV444P,AV_PIX_FMT_YUVA444P, \
                            AV_PIX_FMT_YUV420P9,AV_PIX_FMT_YUV422P9,AV_PIX_FMT_YUV444P9, \
                            AV_PIX_FMT_YUVA420P9,AV_PIX_FMT_YUVA422P9,AV_PIX_FMT_YUVA444P9, \
                            AV_PIX_FMT_YUV420P10,AV_PIX_FMT_YUV422P10,AV_PIX_FMT_YUV444P10, \
                            AV_PIX_FMT_YUVA420P10,AV_PIX_FMT_YUVA422P10,AV_PIX_FMT_YUVA444P10, \
                            AV_PIX_FMT_YUV420P12,AV_PIX_FMT_YUV422P12,AV_PIX_FMT_YUV444P12, \
                            AV_PIX_FMT_YUV420P14,AV_PIX_FMT_YUV422P14,AV_PIX_FMT_YUV444P14, \
                            AV_PIX_FMT_YUV420P16,AV_PIX_FMT_YUV422P16,AV_PIX_FMT_YUV444P16, \
                            AV_PIX_FMT_YUVA420P16,AV_PIX_FMT_YUVA422P16,AV_PIX_FMT_YUVA444P16
#define XYZ_PIXEL_FORMATS   AV_PIX_FMT_XYZ12

static const enum AVPixelFormat rgb_pix_fmts[]  = {RGB_PIXEL_FORMATS};
static const enum AVPixelFormat gray_pix_fmts[] = {GRAY_PIXEL_FORMATS};
static const enum AVPixelFormat yuv_pix_fmts[]  = {YUV_PIXEL_FORMATS};
static const enum AVPixelFormat xyz_pix_fmts[]  = {XYZ_PIXEL_FORMATS,
                                                   YUV_PIXEL_FORMATS};
static const enum AVPixelFormat all_pix_fmts[]  = {RGB_PIXEL_FORMATS,
                                                   GRAY_PIXEL_FORMATS,
                                                   YUV_PIXEL_FORMATS,
                                                   XYZ_PIXEL_FORMATS};

/* marker segments */
/* get sizes and offsets of image, tiles; number of components */
static int get_siz(Jpeg2000DecoderContext *s)
{
    int i;
    int ncomponents;
    uint32_t log2_chroma_wh = 0;
    const enum AVPixelFormat *possible_fmts = NULL;
    int possible_fmts_nb = 0;
    int ret;
    int o_dimx, o_dimy; //original image dimensions.
    int dimx, dimy;

    if (bytestream2_get_bytes_left(&s->g) < 36) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for SIZ\n");
        return AVERROR_INVALIDDATA;
    }

    s->avctx->profile = bytestream2_get_be16u(&s->g); // Rsiz
    s->width          = bytestream2_get_be32u(&s->g); // Width
    s->height         = bytestream2_get_be32u(&s->g); // Height
    s->image_offset_x = bytestream2_get_be32u(&s->g); // X0Siz
    s->image_offset_y = bytestream2_get_be32u(&s->g); // Y0Siz
    s->tile_width     = bytestream2_get_be32u(&s->g); // XTSiz
    s->tile_height    = bytestream2_get_be32u(&s->g); // YTSiz
    s->tile_offset_x  = bytestream2_get_be32u(&s->g); // XT0Siz
    s->tile_offset_y  = bytestream2_get_be32u(&s->g); // YT0Siz
    ncomponents       = bytestream2_get_be16u(&s->g); // CSiz

    if (av_image_check_size2(s->width, s->height, s->avctx->max_pixels, AV_PIX_FMT_NONE, 0, s->avctx)) {
        avpriv_request_sample(s->avctx, "Large Dimensions");
        return AVERROR_PATCHWELCOME;
    }

    if (ncomponents <= 0) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid number of components: %d\n",
               s->ncomponents);
        return AVERROR_INVALIDDATA;
    }

    if (ncomponents > 4) {
        avpriv_request_sample(s->avctx, "Support for %d components",
                              ncomponents);
        return AVERROR_PATCHWELCOME;
    }

    if (s->tile_offset_x < 0 || s->tile_offset_y < 0 ||
        s->image_offset_x < s->tile_offset_x ||
        s->image_offset_y < s->tile_offset_y ||
        s->tile_width  + (int64_t)s->tile_offset_x <= s->image_offset_x ||
        s->tile_height + (int64_t)s->tile_offset_y <= s->image_offset_y
    ) {
        av_log(s->avctx, AV_LOG_ERROR, "Tile offsets are invalid\n");
        return AVERROR_INVALIDDATA;
    }

    if (s->image_offset_x >= s->width || s->image_offset_y >= s->height) {
        av_log(s->avctx, AV_LOG_ERROR, "image offsets outside image");
        return AVERROR_INVALIDDATA;
    }

    if (s->reduction_factor && (s->image_offset_x || s->image_offset_y) ){
        av_log(s->avctx, AV_LOG_ERROR, "reduction factor with image offsets is not fully implemented");
        return AVERROR_PATCHWELCOME;
    }

    s->ncomponents = ncomponents;

    if (s->tile_width <= 0 || s->tile_height <= 0) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid tile dimension %dx%d.\n",
               s->tile_width, s->tile_height);
        return AVERROR_INVALIDDATA;
    }

    if (bytestream2_get_bytes_left(&s->g) < 3 * s->ncomponents) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for %d components in SIZ\n", s->ncomponents);
        return AVERROR_INVALIDDATA;
    }

    for (i = 0; i < s->ncomponents; i++) {
        if (s->cdef[i] < 0) {
            for (i = 0; i < s->ncomponents; i++) {
                s->cdef[i] = i + 1;
            }
            if ((s->ncomponents & 1) == 0)
                s->cdef[s->ncomponents-1] = 0;
        }
    }
    // after here we no longer have to consider negative cdef

    int cdef_used = 0;
    for (i = 0; i < s->ncomponents; i++)
        cdef_used |= 1<<s->cdef[i];

    // Check that the channels we have are what we expect for the number of components
    if (cdef_used != ((int[]){0,2,3,14,15})[s->ncomponents])
        return AVERROR_INVALIDDATA;

    for (i = 0; i < s->ncomponents; i++) { // Ssiz_i XRsiz_i, YRsiz_i
        uint8_t x    = bytestream2_get_byteu(&s->g);
        s->cbps[i]   = (x & 0x7f) + 1;
        s->precision = FFMAX(s->cbps[i], s->precision);
        s->sgnd[i]   = !!(x & 0x80);
        s->cdx[i]    = bytestream2_get_byteu(&s->g);
        s->cdy[i]    = bytestream2_get_byteu(&s->g);
        if (   !s->cdx[i] || s->cdx[i] == 3 || s->cdx[i] > 4
            || !s->cdy[i] || s->cdy[i] == 3 || s->cdy[i] > 4) {
            av_log(s->avctx, AV_LOG_ERROR, "Invalid sample separation %d/%d\n", s->cdx[i], s->cdy[i]);
            return AVERROR_INVALIDDATA;
        }
        int i_remapped = s->cdef[i] ? s->cdef[i]-1 : (s->ncomponents-1);

        log2_chroma_wh |= s->cdy[i] >> 1 << i_remapped * 4 | s->cdx[i] >> 1 << i_remapped * 4 + 2;
    }

    s->numXtiles = ff_jpeg2000_ceildiv(s->width  - s->tile_offset_x, s->tile_width);
    s->numYtiles = ff_jpeg2000_ceildiv(s->height - s->tile_offset_y, s->tile_height);

    // There must be at least a SOT and SOD per tile, their minimum size is 14
    if (s->numXtiles * (uint64_t)s->numYtiles > INT_MAX/sizeof(*s->tile) ||
        s->numXtiles * s->numYtiles * 14LL > bytestream2_size(&s->g)
    ) {
        s->numXtiles = s->numYtiles = 0;
        return AVERROR(EINVAL);
    }

    s->tile = av_calloc(s->numXtiles * s->numYtiles, sizeof(*s->tile));
    if (!s->tile) {
        s->numXtiles = s->numYtiles = 0;
        return AVERROR(ENOMEM);
    }

    for (i = 0; i < s->numXtiles * s->numYtiles; i++) {
        Jpeg2000Tile *tile = s->tile + i;

        tile->comp = av_mallocz(s->ncomponents * sizeof(*tile->comp));
        if (!tile->comp)
            return AVERROR(ENOMEM);
    }

    /* compute image size with reduction factor */
    o_dimx = ff_jpeg2000_ceildivpow2(s->width  - s->image_offset_x,
                                               s->reduction_factor);
    o_dimy = ff_jpeg2000_ceildivpow2(s->height - s->image_offset_y,
                                               s->reduction_factor);
    dimx = ff_jpeg2000_ceildiv(o_dimx, s->cdx[0]);
    dimy = ff_jpeg2000_ceildiv(o_dimy, s->cdy[0]);
    for (i = 1; i < s->ncomponents; i++) {
        dimx = FFMAX(dimx, ff_jpeg2000_ceildiv(o_dimx, s->cdx[i]));
        dimy = FFMAX(dimy, ff_jpeg2000_ceildiv(o_dimy, s->cdy[i]));
    }

    ret = ff_set_dimensions(s->avctx, dimx << s->avctx->lowres, dimy << s->avctx->lowres);
    if (ret < 0)
        return ret;

    if (s->avctx->profile == AV_PROFILE_JPEG2000_DCINEMA_2K ||
        s->avctx->profile == AV_PROFILE_JPEG2000_DCINEMA_4K) {
        possible_fmts = xyz_pix_fmts;
        possible_fmts_nb = FF_ARRAY_ELEMS(xyz_pix_fmts);
    } else {
        switch (s->colour_space) {
        case 16:
            possible_fmts = rgb_pix_fmts;
            possible_fmts_nb = FF_ARRAY_ELEMS(rgb_pix_fmts);
            break;
        case 17:
            possible_fmts = gray_pix_fmts;
            possible_fmts_nb = FF_ARRAY_ELEMS(gray_pix_fmts);
            break;
        case 18:
            possible_fmts = yuv_pix_fmts;
            possible_fmts_nb = FF_ARRAY_ELEMS(yuv_pix_fmts);
            break;
        default:
            possible_fmts = all_pix_fmts;
            possible_fmts_nb = FF_ARRAY_ELEMS(all_pix_fmts);
            break;
        }
    }
    if (   s->avctx->pix_fmt != AV_PIX_FMT_NONE
        && !pix_fmt_match(s->avctx->pix_fmt, ncomponents, s->precision, log2_chroma_wh, s->pal8))
            s->avctx->pix_fmt = AV_PIX_FMT_NONE;
    if (s->avctx->pix_fmt == AV_PIX_FMT_NONE)
        for (i = 0; i < possible_fmts_nb; ++i) {
            if (pix_fmt_match(possible_fmts[i], ncomponents, s->precision, log2_chroma_wh, s->pal8)) {
                s->avctx->pix_fmt = possible_fmts[i];
                break;
            }
        }

    if (i == possible_fmts_nb) {
        if (ncomponents == 4 &&
            s->cdy[0] == 1 && s->cdx[0] == 1 &&
            s->cdy[1] == 1 && s->cdx[1] == 1 &&
            s->cdy[2] == s->cdy[3] && s->cdx[2] == s->cdx[3]) {
            if (s->precision == 8 && s->cdy[2] == 2 && s->cdx[2] == 2 && !s->pal8) {
                s->avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
                s->cdef[0] = 0;
                s->cdef[1] = 1;
                s->cdef[2] = 2;
                s->cdef[3] = 3;
                i = 0;
            }
        } else if (ncomponents == 3 && s->precision == 8 &&
                   s->cdx[0] == s->cdx[1] && s->cdx[0] == s->cdx[2] &&
                   s->cdy[0] == s->cdy[1] && s->cdy[0] == s->cdy[2]) {
            s->avctx->pix_fmt = AV_PIX_FMT_RGB24;
            i = 0;
        } else if (ncomponents == 2 && s->precision == 8 &&
                   s->cdx[0] == s->cdx[1] && s->cdy[0] == s->cdy[1]) {
            s->avctx->pix_fmt = AV_PIX_FMT_YA8;
            i = 0;
        } else if (ncomponents == 2 && s->precision == 16 &&
                   s->cdx[0] == s->cdx[1] && s->cdy[0] == s->cdy[1]) {
            s->avctx->pix_fmt = AV_PIX_FMT_YA16;
            i = 0;
        } else if (ncomponents == 1 && s->precision == 8) {
            s->avctx->pix_fmt = AV_PIX_FMT_GRAY8;
            i = 0;
        } else if (ncomponents == 1 && s->precision == 12) {
            s->avctx->pix_fmt = AV_PIX_FMT_GRAY16LE;
            i = 0;
        }
    }


    if (i == possible_fmts_nb) {
        av_log(s->avctx, AV_LOG_ERROR,
               "Unknown pix_fmt, profile: %d, colour_space: %d, "
               "components: %d, precision: %d\n"
               "cdx[0]: %d, cdy[0]: %d\n"
               "cdx[1]: %d, cdy[1]: %d\n"
               "cdx[2]: %d, cdy[2]: %d\n"
               "cdx[3]: %d, cdy[3]: %d\n",
               s->avctx->profile, s->colour_space, ncomponents, s->precision,
               s->cdx[0],
               s->cdy[0],
               ncomponents > 1 ? s->cdx[1] : 0,
               ncomponents > 1 ? s->cdy[1] : 0,
               ncomponents > 2 ? s->cdx[2] : 0,
               ncomponents > 2 ? s->cdy[2] : 0,
               ncomponents > 3 ? s->cdx[3] : 0,
               ncomponents > 3 ? s->cdy[3] : 0);
        return AVERROR_PATCHWELCOME;
    }
    s->avctx->bits_per_raw_sample = s->precision;
    return 0;
}
/* get extended capabilities (CAP) marker segment */
static int get_cap(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c)
{
    uint32_t Pcap;
    uint16_t Ccap_i[32] = { 0 };
    uint16_t Ccap_15;
    uint8_t P;

    if (bytestream2_get_bytes_left(&s->g) < 6) {
        av_log(s->avctx, AV_LOG_ERROR, "Underflow while parsing the CAP marker\n");
        return AVERROR_INVALIDDATA;
    }

    Pcap = bytestream2_get_be32u(&s->g);
    s->isHT = (Pcap >> (31 - (15 - 1))) & 1;
    for (int i = 0; i < 32; i++) {
        if ((Pcap >> (31 - i)) & 1)
            Ccap_i[i] = bytestream2_get_be16u(&s->g);
    }
    Ccap_15 = Ccap_i[14];
    if (s->isHT == 1) {
        av_log(s->avctx, AV_LOG_INFO, "This codestream uses the HT block coder.\n");
        // Bits 14-15
        switch ((Ccap_15 >> 14) & 0x3) {
            case 0x3:
                s->Ccap15_b14_15 = HTJ2K_MIXED;
                break;
            case 0x1:
                s->Ccap15_b14_15 = HTJ2K_HTDECLARED;
                break;
            case 0x0:
                s->Ccap15_b14_15 = HTJ2K_HTONLY;
                break;
            default:
                av_log(s->avctx, AV_LOG_ERROR, "Unknown CCap value.\n");
                return AVERROR(EINVAL);
                break;
        }
        // Bit 13
        if ((Ccap_15 >> 13) & 1) {
            av_log(s->avctx, AV_LOG_ERROR, "MULTIHT set is not supported.\n");
            return AVERROR_PATCHWELCOME;
        }
        // Bit 12
        s->Ccap15_b12 = (Ccap_15 >> 12) & 1;
        // Bit 11
        s->Ccap15_b11 = (Ccap_15 >> 11) & 1;
        // Bit 5
        s->Ccap15_b05 = (Ccap_15 >> 5) & 1;
        // Bit 0-4
        P = Ccap_15 & 0x1F;
        if (!P)
            s->HT_B = 8;
        else if (P < 20)
            s->HT_B = P + 8;
        else if (P < 31)
            s->HT_B = 4 * (P - 19) + 27;
        else
            s->HT_B = 74;

        if (s->HT_B > 31) {
            av_log(s->avctx, AV_LOG_ERROR, "Codestream exceeds available precision (B > 31).\n");
            return AVERROR_PATCHWELCOME;
        }
    }
    return 0;
}

/* get common part for COD and COC segments */
static int get_cox(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c)
{
    uint8_t byte;

    if (bytestream2_get_bytes_left(&s->g) < 5) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for COX\n");
        return AVERROR_INVALIDDATA;
    }

    /*  nreslevels = number of resolution levels
                   = number of decomposition level +1 */
    c->nreslevels = bytestream2_get_byteu(&s->g) + 1;
    if (c->nreslevels >= JPEG2000_MAX_RESLEVELS) {
        av_log(s->avctx, AV_LOG_ERROR, "nreslevels %d is invalid\n", c->nreslevels);
        return AVERROR_INVALIDDATA;
    }

    if (c->nreslevels <= s->reduction_factor) {
        /* we are forced to update reduction_factor as its requested value is
           not compatible with this bitstream, and as we might have used it
           already in setup earlier we have to fail this frame until
           reinitialization is implemented */
        av_log(s->avctx, AV_LOG_ERROR, "reduction_factor too large for this bitstream, max is %d\n", c->nreslevels - 1);
        s->reduction_factor = c->nreslevels - 1;
        return AVERROR(EINVAL);
    }

    /* compute number of resolution levels to decode */
    c->nreslevels2decode = c->nreslevels - s->reduction_factor;

    c->log2_cblk_width  = (bytestream2_get_byteu(&s->g) & 15) + 2; // cblk width
    c->log2_cblk_height = (bytestream2_get_byteu(&s->g) & 15) + 2; // cblk height

    if (c->log2_cblk_width > 10 || c->log2_cblk_height > 10 ||
        c->log2_cblk_width + c->log2_cblk_height > 12) {
        av_log(s->avctx, AV_LOG_ERROR, "cblk size invalid\n");
        return AVERROR_INVALIDDATA;
    }

    c->cblk_style = bytestream2_get_byteu(&s->g);
    if (c->cblk_style != 0) { // cblk style
        if (c->cblk_style & JPEG2000_CTSY_HTJ2K_M || c->cblk_style & JPEG2000_CTSY_HTJ2K_F) {
            av_log(s->avctx,AV_LOG_TRACE,"High Throughput jpeg 2000 codestream.\n");
        } else {
            av_log(s->avctx, AV_LOG_WARNING, "extra cblk styles %X\n", c->cblk_style);
            if (c->cblk_style & JPEG2000_CBLK_BYPASS)
                av_log(s->avctx, AV_LOG_WARNING, "Selective arithmetic coding bypass\n");
        }
    }
    c->transform = bytestream2_get_byteu(&s->g); // DWT transformation type
    /* set integer 9/7 DWT in case of BITEXACT flag */
    if ((s->avctx->flags & AV_CODEC_FLAG_BITEXACT) && (c->transform == FF_DWT97))
        c->transform = FF_DWT97_INT;
#if FF_API_CODEC_PROPS
    else if (c->transform == FF_DWT53) {
FF_DISABLE_DEPRECATION_WARNINGS
        s->avctx->properties |= FF_CODEC_PROPERTY_LOSSLESS;
FF_ENABLE_DEPRECATION_WARNINGS
    }
#endif

    if (c->csty & JPEG2000_CSTY_PREC) {
        int i;
        for (i = 0; i < c->nreslevels; i++) {
            byte = bytestream2_get_byte(&s->g);
            c->log2_prec_widths[i]  =  byte       & 0x0F;    // precinct PPx
            c->log2_prec_heights[i] = (byte >> 4) & 0x0F;    // precinct PPy
            if (i)
                if (c->log2_prec_widths[i] == 0 || c->log2_prec_heights[i] == 0) {
                    av_log(s->avctx, AV_LOG_ERROR, "PPx %d PPy %d invalid\n",
                           c->log2_prec_widths[i], c->log2_prec_heights[i]);
                    c->log2_prec_widths[i] = c->log2_prec_heights[i] = 1;
                    return AVERROR_INVALIDDATA;
                }
        }
    } else {
        memset(c->log2_prec_widths , 15, sizeof(c->log2_prec_widths ));
        memset(c->log2_prec_heights, 15, sizeof(c->log2_prec_heights));
    }
    return 0;
}

/* get coding parameters for a particular tile or whole image*/
static int get_cod(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c,
                   const uint8_t *properties)
{
    Jpeg2000CodingStyle tmp;
    int compno, ret;

    if (bytestream2_get_bytes_left(&s->g) < 5) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for COD\n");
        return AVERROR_INVALIDDATA;
    }

    tmp.csty = bytestream2_get_byteu(&s->g);

    // get progression order
    tmp.prog_order = bytestream2_get_byteu(&s->g);

    tmp.nlayers    = bytestream2_get_be16u(&s->g);
    tmp.mct        = bytestream2_get_byteu(&s->g); // multiple component transformation

    if (tmp.mct && s->ncomponents < 3) {
        av_log(s->avctx, AV_LOG_ERROR,
               "MCT %"PRIu8" with too few components (%d)\n",
               tmp.mct, s->ncomponents);
        return AVERROR_INVALIDDATA;
    }

    if ((ret = get_cox(s, &tmp)) < 0)
        return ret;
    tmp.init = 1;
    for (compno = 0; compno < s->ncomponents; compno++)
        if (!(properties[compno] & HAD_COC))
            memcpy(c + compno, &tmp, sizeof(tmp));
    return 0;
}

/* Get coding parameters for a component in the whole image or a
 * particular tile. */
static int get_coc(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c,
                   uint8_t *properties)
{
    int compno, ret;
    uint8_t has_eph, has_sop;

    if (bytestream2_get_bytes_left(&s->g) < 2) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for COC\n");
        return AVERROR_INVALIDDATA;
    }

    compno = bytestream2_get_byteu(&s->g);

    if (compno >= s->ncomponents) {
        av_log(s->avctx, AV_LOG_ERROR,
               "Invalid compno %d. There are %d components in the image.\n",
               compno, s->ncomponents);
        return AVERROR_INVALIDDATA;
    }

    c      += compno;
    has_eph = c->csty & JPEG2000_CSTY_EPH;
    has_sop = c->csty & JPEG2000_CSTY_SOP;
    c->csty = bytestream2_get_byteu(&s->g);
    c->csty |= has_eph; //do not override eph present bits from COD
    c->csty |= has_sop; //do not override sop present bits from COD

    if ((ret = get_cox(s, c)) < 0)
        return ret;

    properties[compno] |= HAD_COC;
    c->init = 1;
    return 0;
}

static int get_rgn(Jpeg2000DecoderContext *s, int n)
{
    uint16_t compno;
    compno = (s->ncomponents < 257)? bytestream2_get_byte(&s->g):
                                     bytestream2_get_be16u(&s->g);
    if (bytestream2_get_byte(&s->g)) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid RGN header.\n");
        return AVERROR_INVALIDDATA; // SRgn field value is 0
    }
    // SPrgn field
    // Currently compno cannot be greater than 4.
    // However, future implementation should support compno up to 65536
    if (compno < s->ncomponents) {
        int v;
        if (s->curtileno == -1) {
            v =  bytestream2_get_byte(&s->g);
            if (v > 30)
                return AVERROR_PATCHWELCOME;
            s->roi_shift[compno] = v;
        } else {
            if (s->tile[s->curtileno].tp_idx != 0)
                return AVERROR_INVALIDDATA; // marker occurs only in first tile part of tile
            v = bytestream2_get_byte(&s->g);
            if (v > 30)
                return AVERROR_PATCHWELCOME;
            s->tile[s->curtileno].comp[compno].roi_shift = v;
        }
        return 0;
    }
    return AVERROR_INVALIDDATA;
}

/* Get common part for QCD and QCC segments. */
static int get_qcx(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q)
{
    int i, x;

    if (bytestream2_get_bytes_left(&s->g) < 1)
        return AVERROR_INVALIDDATA;

    x = bytestream2_get_byteu(&s->g); // Sqcd

    q->nguardbits = x >> 5;
    q->quantsty   = x & 0x1f;

    if (q->quantsty == JPEG2000_QSTY_NONE) {
        n -= 3;
        if (bytestream2_get_bytes_left(&s->g) < n ||
            n > JPEG2000_MAX_DECLEVELS*3)
            return AVERROR_INVALIDDATA;
        for (i = 0; i < n; i++)
            q->expn[i] = bytestream2_get_byteu(&s->g) >> 3;
    } else if (q->quantsty == JPEG2000_QSTY_SI) {
        if (bytestream2_get_bytes_left(&s->g) < 2)
            return AVERROR_INVALIDDATA;
        x          = bytestream2_get_be16u(&s->g);
        q->expn[0] = x >> 11;
        q->mant[0] = x & 0x7ff;
        for (i = 1; i < JPEG2000_MAX_DECLEVELS * 3; i++) {
            int curexpn = FFMAX(0, q->expn[0] - (i - 1) / 3);
            q->expn[i] = curexpn;
            q->mant[i] = q->mant[0];
        }
    } else {
        n = (n - 3) >> 1;
        if (bytestream2_get_bytes_left(&s->g) < 2 * n ||
            n > JPEG2000_MAX_DECLEVELS*3)
            return AVERROR_INVALIDDATA;
        for (i = 0; i < n; i++) {
            x          = bytestream2_get_be16u(&s->g);
            q->expn[i] = x >> 11;
            q->mant[i] = x & 0x7ff;
        }
    }
    return 0;
}

/* Get quantization parameters for a particular tile or a whole image. */
static int get_qcd(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q,
                   const uint8_t *properties)
{
    Jpeg2000QuantStyle tmp;
    int compno, ret;

    memset(&tmp, 0, sizeof(tmp));

    if ((ret = get_qcx(s, n, &tmp)) < 0)
        return ret;
    for (compno = 0; compno < s->ncomponents; compno++)
        if (!(properties[compno] & HAD_QCC))
            memcpy(q + compno, &tmp, sizeof(tmp));
    return 0;
}

/* Get quantization parameters for a component in the whole image
 * on in a particular tile. */
static int get_qcc(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q,
                   uint8_t *properties)
{
    int compno;

    if (bytestream2_get_bytes_left(&s->g) < 1)
        return AVERROR_INVALIDDATA;

    compno = bytestream2_get_byteu(&s->g);

    if (compno >= s->ncomponents) {
        av_log(s->avctx, AV_LOG_ERROR,
               "Invalid compno %d. There are %d components in the image.\n",
               compno, s->ncomponents);
        return AVERROR_INVALIDDATA;
    }

    properties[compno] |= HAD_QCC;
    return get_qcx(s, n - 1, q + compno);
}

static int get_poc(Jpeg2000DecoderContext *s, int size, Jpeg2000POC *p)
{
    int i;
    int elem_size = s->ncomponents <= 257 ? 7 : 9;
    Jpeg2000POC tmp = {{{0}}};

    if (bytestream2_get_bytes_left(&s->g) < 5 || size < 2 + elem_size) {
        av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for POC\n");
        return AVERROR_INVALIDDATA;
    }

    if (elem_size > 7) {
        avpriv_request_sample(s->avctx, "Fat POC not supported");
        return AVERROR_PATCHWELCOME;
    }

    tmp.nb_poc = (size - 2) / elem_size;
    if (tmp.nb_poc > MAX_POCS) {
        avpriv_request_sample(s->avctx, "Too many POCs (%d)", tmp.nb_poc);
        return AVERROR_PATCHWELCOME;
    }

    for (i = 0; i<tmp.nb_poc; i++) {
        Jpeg2000POCEntry *e = &tmp.poc[i];
        e->RSpoc  = bytestream2_get_byteu(&s->g);
        e->CSpoc  = bytestream2_get_byteu(&s->g);
        e->LYEpoc = bytestream2_get_be16u(&s->g);
        e->REpoc  = bytestream2_get_byteu(&s->g);
        e->CEpoc  = bytestream2_get_byteu(&s->g);
        e->Ppoc   = bytestream2_get_byteu(&s->g);
        if (!e->CEpoc)
            e->CEpoc = 256;
        if (e->CEpoc > s->ncomponents)
            e->CEpoc = s->ncomponents;
        if (   e->RSpoc >= e->REpoc || e->REpoc > 33
            || e->CSpoc >= e->CEpoc || e->CEpoc > s->ncomponents
            || !e->LYEpoc) {
            av_log(s->avctx, AV_LOG_ERROR, "POC Entry %d is invalid (%d, %d, %d, %d, %d, %d)\n", i,
                e->RSpoc, e->CSpoc, e->LYEpoc, e->REpoc, e->CEpoc, e->Ppoc
            );
            return AVERROR_INVALIDDATA;
        }
    }

    if (!p->nb_poc || p->is_default) {
        *p = tmp;
    } else {
        if (p->nb_poc + tmp.nb_poc > MAX_POCS) {
            av_log(s->avctx, AV_LOG_ERROR, "Insufficient space for POC\n");
            return AVERROR_INVALIDDATA;
        }
        memcpy(p->poc + p->nb_poc, tmp.poc, tmp.nb_poc * sizeof(tmp.poc[0]));
        p->nb_poc += tmp.nb_poc;
    }

    p->is_default = 0;

    return 0;
}


/* Get start of tile segment. */
static int get_sot(Jpeg2000DecoderContext *s, int n)
{
    Jpeg2000TilePart *tp;
    uint16_t Isot;
    uint32_t Psot;
    unsigned TPsot;

    if (bytestream2_get_bytes_left(&s->g) < 8)
        return AVERROR_INVALIDDATA;

    s->curtileno = 0;
    Isot = bytestream2_get_be16u(&s->g);        // Isot
    if (Isot >= s->numXtiles * s->numYtiles)
        return AVERROR_INVALIDDATA;

    s->curtileno = Isot;
    Psot  = bytestream2_get_be32u(&s->g);       // Psot
    TPsot = bytestream2_get_byteu(&s->g);       // TPsot

    /* Read TNSot but not used */
    bytestream2_get_byteu(&s->g);               // TNsot

    if (!Psot)
        Psot = bytestream2_get_bytes_left(&s->g) - 2 + n + 2;

    if (Psot > bytestream2_get_bytes_left(&s->g) - 2 + n + 2) {
        av_log(s->avctx, AV_LOG_ERROR, "Psot %"PRIu32" too big\n", Psot);
        return AVERROR_INVALIDDATA;
    }

    if (TPsot >= FF_ARRAY_ELEMS(s->tile[Isot].tile_part)) {
        avpriv_request_sample(s->avctx, "Too many tile parts");
        return AVERROR_PATCHWELCOME;
    }

    s->tile[Isot].tp_idx = TPsot;
    tp             = s->tile[Isot].tile_part + TPsot;
    tp->tile_index = Isot;
    tp->tp_end     = s->g.buffer + Psot - n - 2;

    if (!TPsot) {
        Jpeg2000Tile *tile = s->tile + s->curtileno;

        /* copy defaults */
        memcpy(tile->codsty, s->codsty, s->ncomponents * sizeof(Jpeg2000CodingStyle));
        memcpy(tile->qntsty, s->qntsty, s->ncomponents * sizeof(Jpeg2000QuantStyle));
        memcpy(&tile->poc  , &s->poc  , sizeof(tile->poc));
        tile->poc.is_default = 1;
    }

    return 0;
}

static int read_crg(Jpeg2000DecoderContext *s, int n)
{
    if (s->ncomponents*4 != n - 2) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid CRG marker.\n");
        return AVERROR_INVALIDDATA;
    }
    bytestream2_skip(&s->g, n - 2);
    return 0;
}

static int read_cpf(Jpeg2000DecoderContext *s, int n)
{
    if (bytestream2_get_bytes_left(&s->g) < (n - 2))
        return AVERROR_INVALIDDATA;
    bytestream2_skip(&s->g, n - 2);
    return 0;
}

/* Tile-part lengths: see ISO 15444-1:2002, section A.7.1
 * Used to know the number of tile parts and lengths.
 * There may be multiple TLMs in the header.
 * TODO: The function is not used for tile-parts management, nor anywhere else.
 * It can be useful to allocate memory for tile parts, before managing the SOT
 * markers. Parsing the TLM header is needed to increment the input header
 * buffer.
 * This marker is mandatory for DCI. */
static int get_tlm(Jpeg2000DecoderContext *s, int n)
{
    uint8_t Stlm, ST, SP, tile_tlm, i;
    bytestream2_get_byte(&s->g);               /* Ztlm: skipped */
    Stlm = bytestream2_get_byte(&s->g);

    // too complex ? ST = ((Stlm >> 4) & 0x01) + ((Stlm >> 4) & 0x02);
    ST = (Stlm >> 4) & 0x03;
    if (ST == 0x03) {
        av_log(s->avctx, AV_LOG_ERROR, "TLM marker contains invalid ST value.\n");
        return AVERROR_INVALIDDATA;
    }

    SP       = (Stlm >> 6) & 0x01;
    tile_tlm = (n - 4) / ((SP + 1) * 2 + ST);
    for (i = 0; i < tile_tlm; i++) {
        switch (ST) {
        case 0:
            break;
        case 1:
            bytestream2_get_byte(&s->g);
            break;
        case 2:
            bytestream2_get_be16(&s->g);
            break;
        }
        if (SP == 0) {
            bytestream2_get_be16(&s->g);
        } else {
            bytestream2_get_be32(&s->g);
        }
    }
    return 0;
}

static int get_plt(Jpeg2000DecoderContext *s, int n)
{
    int i;
    int v;

    av_log(s->avctx, AV_LOG_DEBUG,
            "PLT marker at pos 0x%X\n", bytestream2_tell(&s->g) - 4);

    if (n < 4)
        return AVERROR_INVALIDDATA;

    /*Zplt =*/ bytestream2_get_byte(&s->g);

    for (i = 0; i < n - 3; i++) {
        v = bytestream2_get_byte(&s->g);
    }
    if (v & 0x80)
        return AVERROR_INVALIDDATA;

    return 0;
}

static int get_ppm(Jpeg2000DecoderContext *s, int n)
{
    void *new;

    if (n < 3) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid length for PPM data.\n");
        return AVERROR_INVALIDDATA;
    }
    bytestream2_get_byte(&s->g); //Zppm is skipped and not used
    new = av_realloc(s->packed_headers,
                     s->packed_headers_size + n - 3);
    if (new) {
        s->packed_headers = new;
    } else
        return AVERROR(ENOMEM);
    s->has_ppm = 1;
    memset(&s->packed_headers_stream, 0, sizeof(s->packed_headers_stream));
    bytestream2_get_bufferu(&s->g, s->packed_headers + s->packed_headers_size,
                            n - 3);
    s->packed_headers_size += n - 3;

    return 0;
}

static int get_ppt(Jpeg2000DecoderContext *s, int n)
{
    Jpeg2000Tile *tile;
    void *new;

    if (n < 3) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid length for PPT data.\n");
        return AVERROR_INVALIDDATA;
    }
    if (s->curtileno < 0)
        return AVERROR_INVALIDDATA;

    tile = &s->tile[s->curtileno];
    if (tile->tp_idx != 0) {
        av_log(s->avctx, AV_LOG_ERROR,
               "PPT marker can occur only on first tile part of a tile.\n");
        return AVERROR_INVALIDDATA;
    }

    tile->has_ppt = 1;  // this tile has a ppt marker
    bytestream2_get_byte(&s->g); // Zppt is skipped and not used
    new = av_realloc(tile->packed_headers,
                     tile->packed_headers_size + n - 3);
    if (new) {
        tile->packed_headers = new;
    } else
        return AVERROR(ENOMEM);
    memset(&tile->packed_headers_stream, 0, sizeof(tile->packed_headers_stream));
    bytestream2_get_bufferu(&s->g, tile->packed_headers + tile->packed_headers_size, n - 3);
    tile->packed_headers_size += n - 3;

    return 0;
}

static int init_tile(Jpeg2000DecoderContext *s, int tileno)
{
    int compno;
    int tilex = tileno % s->numXtiles;
    int tiley = tileno / s->numXtiles;
    Jpeg2000Tile *tile = s->tile + tileno;

    if (!tile->comp)
        return AVERROR(ENOMEM);

    tile->coord[0][0] = av_clip(tilex       * (int64_t)s->tile_width  + s->tile_offset_x, s->image_offset_x, s->width);
    tile->coord[0][1] = av_clip((tilex + 1) * (int64_t)s->tile_width  + s->tile_offset_x, s->image_offset_x, s->width);
    tile->coord[1][0] = av_clip(tiley       * (int64_t)s->tile_height + s->tile_offset_y, s->image_offset_y, s->height);
    tile->coord[1][1] = av_clip((tiley + 1) * (int64_t)s->tile_height + s->tile_offset_y, s->image_offset_y, s->height);

    for (compno = 0; compno < s->ncomponents; compno++) {
        Jpeg2000Component *comp = tile->comp + compno;
        Jpeg2000CodingStyle *codsty = tile->codsty + compno;
        Jpeg2000QuantStyle  *qntsty = tile->qntsty + compno;
        int ret; // global bandno

        comp->coord_o[0][0] = tile->coord[0][0];
        comp->coord_o[0][1] = tile->coord[0][1];
        comp->coord_o[1][0] = tile->coord[1][0];
        comp->coord_o[1][1] = tile->coord[1][1];

        comp->coord_o[0][0] = ff_jpeg2000_ceildiv(comp->coord_o[0][0], s->cdx[compno]);
        comp->coord_o[0][1] = ff_jpeg2000_ceildiv(comp->coord_o[0][1], s->cdx[compno]);
        comp->coord_o[1][0] = ff_jpeg2000_ceildiv(comp->coord_o[1][0], s->cdy[compno]);
        comp->coord_o[1][1] = ff_jpeg2000_ceildiv(comp->coord_o[1][1], s->cdy[compno]);

        comp->coord[0][0] = ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], s->reduction_factor);
        comp->coord[0][1] = ff_jpeg2000_ceildivpow2(comp->coord_o[0][1], s->reduction_factor);
        comp->coord[1][0] = ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], s->reduction_factor);
        comp->coord[1][1] = ff_jpeg2000_ceildivpow2(comp->coord_o[1][1], s->reduction_factor);

        if (!comp->roi_shift)
            comp->roi_shift = s->roi_shift[compno];
        if (!codsty->init)
            return AVERROR_INVALIDDATA;
        if (s->isHT && (!s->Ccap15_b05) && (!codsty->transform)) {
            av_log(s->avctx, AV_LOG_ERROR, "Transformation = 0 (lossy DWT) is found in HTREV HT set\n");
            return AVERROR_INVALIDDATA;
        }
        if (s->isHT && s->Ccap15_b14_15 != (codsty->cblk_style >> 6) && s->Ccap15_b14_15 != HTJ2K_HTONLY) {
            av_log(s->avctx, AV_LOG_ERROR, "SPcod/SPcoc value does not match bit 14-15 values of Ccap15\n");
            return AVERROR_INVALIDDATA;
        }
        if (ret = ff_jpeg2000_init_component(comp, codsty, qntsty,
                                             s->cbps[compno], s->cdx[compno],
                                             s->cdy[compno], s->avctx))
            return ret;
    }
    return 0;
}

/* Read the number of coding passes. */
static int getnpasses(Jpeg2000DecoderContext *s)
{
    int num;
    if (!get_bits(s, 1))
        return 1;
    if (!get_bits(s, 1))
        return 2;
    if ((num = get_bits(s, 2)) != 3)
        return num < 0 ? num : 3 + num;
    if ((num = get_bits(s, 5)) != 31)
        return num < 0 ? num : 6 + num;
    num = get_bits(s, 7);
    return num < 0 ? num : 37 + num;
}

static int getlblockinc(Jpeg2000DecoderContext *s)
{
    int res = 0, ret;
    while (ret = get_bits(s, 1)) {
        if (ret < 0)
            return ret;
        res++;
    }
    return res;
}

static inline void select_header(Jpeg2000DecoderContext *s, const Jpeg2000Tile *tile,
                                 int *tp_index)
{
    s->g = tile->tile_part[*tp_index].header_tpg;
    if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
        av_log(s->avctx, AV_LOG_WARNING, "Packet header bytes in PPM marker segment is too short.\n");
        if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
            s->g = tile->tile_part[++(*tp_index)].tpg;
        }
    }
}

static inline void select_stream(Jpeg2000DecoderContext *s, const Jpeg2000Tile *tile,
                                 int *tp_index, const Jpeg2000CodingStyle *codsty)
{
    int32_t is_endof_tp;

    s->g = tile->tile_part[*tp_index].tpg;
    is_endof_tp = bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8;
    // Following while loop is necessary because a tilepart may include only SOD marker.
    // Such a tilepart has neither packet header nor compressed data.
    while (is_endof_tp) {
        if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
            s->g = tile->tile_part[++(*tp_index)].tpg;
            is_endof_tp = bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8;
        } else {
            is_endof_tp = 0;
        }
    }
    if (codsty->csty & JPEG2000_CSTY_SOP) {
        if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
            bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
        else
            av_log(s->avctx, AV_LOG_ERROR, "SOP marker not found. instead %X\n", bytestream2_peek_be32(&s->g));
    }
}

static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile, int *tp_index,
                                  const Jpeg2000CodingStyle *codsty,
                                  Jpeg2000ResLevel *rlevel, int precno,
                                  int layno, const uint8_t *expn, int numgbits)
{
    int bandno, cblkno, ret, nb_code_blocks;
    int cwsno;

    if (layno < rlevel->band[0].prec[precno].decoded_layers)
        return 0;
    rlevel->band[0].prec[precno].decoded_layers = layno + 1;
    // Select stream to read from
    if (s->has_ppm)
        select_header(s, tile, tp_index);
    else if (tile->has_ppt)
        s->g = tile->packed_headers_stream;
    else
        select_stream(s, tile, tp_index, codsty);

    if (!(ret = get_bits(s, 1))) {
        jpeg2000_flush(s);
        goto skip_data;
    } else if (ret < 0)
        return ret;

    for (bandno = 0; bandno < rlevel->nbands; bandno++) {
        Jpeg2000Band *band = rlevel->band + bandno;
        Jpeg2000Prec *prec = band->prec + precno;

        if (band->coord[0][0] == band->coord[0][1] ||
            band->coord[1][0] == band->coord[1][1])
            continue;
        nb_code_blocks =  prec->nb_codeblocks_height *
                          prec->nb_codeblocks_width;
        for (cblkno = 0; cblkno < nb_code_blocks; cblkno++) {
            Jpeg2000Cblk *cblk = prec->cblk + cblkno;
            int incl, newpasses, llen;
            void *tmp;

            if (!cblk->incl) {
                incl = 0;
                cblk->modes = codsty->cblk_style;
                if (cblk->modes >= JPEG2000_CTSY_HTJ2K_F)
                    cblk->ht_plhd = HT_PLHD_ON;
                if (layno > 0)
                    incl = tag_tree_decode(s, prec->cblkincl + cblkno, 0 + 1) == 0;
                incl = tag_tree_decode(s, prec->cblkincl + cblkno, layno + 1) == layno;

                if (incl) {
                    int zbp = tag_tree_decode(s, prec->zerobits + cblkno, 100);
                    int v = expn[bandno] + numgbits - 1 - (zbp - tile->comp->roi_shift);
                    if (v < 0 || v > 30) {
                        av_log(s->avctx, AV_LOG_ERROR,
                               "nonzerobits %d invalid or unsupported\n", v);
                        return AVERROR_INVALIDDATA;
                    }
                    cblk->incl = 1;
                    cblk->nonzerobits = v;
                    cblk->zbp = zbp;
                    cblk->lblock = 3;
                }
            } else {
                incl = get_bits(s, 1);
            }

            if (incl) {
                uint8_t bypass_term_threshold = 0;
                uint8_t bits_to_read = 0;
                uint32_t segment_bytes = 0;
                int32_t segment_passes = 0;
                uint8_t next_segment_passes = 0;
                int32_t href_passes, pass_bound;
                uint32_t tmp_length = 0;
                int32_t newpasses_copy, npasses_copy;

                if ((newpasses = getnpasses(s)) <= 0)
                    return newpasses;
                if (cblk->npasses + newpasses >= JPEG2000_MAX_PASSES) {
                    avpriv_request_sample(s->avctx, "Too many passes");
                    return AVERROR_PATCHWELCOME;
                }
                if ((llen = getlblockinc(s)) < 0)
                    return llen;
                if (cblk->lblock + llen + av_log2(newpasses) > 16) {
                    avpriv_request_sample(s->avctx,
                                          "Block with length beyond 16 bits");
                    return AVERROR_PATCHWELCOME;
                }
                cblk->nb_lengthinc = 0;
                cblk->nb_terminationsinc = 0;
                av_free(cblk->lengthinc);
                cblk->lengthinc = av_calloc(newpasses, sizeof(*cblk->lengthinc));
                if (!cblk->lengthinc)
                    return AVERROR(ENOMEM);
                tmp = av_realloc_array(cblk->data_start, cblk->nb_terminations + newpasses + 1,
                                       sizeof(*cblk->data_start));
                if (!tmp)
                    return AVERROR(ENOMEM);
                cblk->data_start = tmp;
                cblk->lblock += llen;

                // Count number of necessary terminations for non HT code block
                newpasses_copy = newpasses;
                npasses_copy = cblk->npasses;
                if (!(cblk->modes & JPEG2000_CTSY_HTJ2K_F)) {
                    do {
                        int newpasses1 = 0;

                        while (newpasses1 < newpasses_copy) {
                            newpasses1++;
                            if (needs_termination(codsty->cblk_style, npasses_copy + newpasses1 - 1)) {
                                cblk->nb_terminationsinc++;
                                break;
                            }
                        }
                        npasses_copy += newpasses1;
                        newpasses_copy -= newpasses1;
                    } while (newpasses_copy);
                }

                if (cblk->ht_plhd) {
                    href_passes = (cblk->npasses + newpasses - 1) % 3;
                    segment_passes = newpasses - href_passes;
                    pass_bound = 2;
                    bits_to_read = cblk->lblock;
                    if (segment_passes < 1) {
                        // No possible HT Cleanup pass here; may have placeholder passes
                        // or an original J2K block bit-stream (in MIXED mode).
                        segment_passes = newpasses;
                        while (pass_bound <= segment_passes) {
                            bits_to_read++;
                            pass_bound += pass_bound;
                        }
                        segment_bytes = get_bits(s, bits_to_read);
                        if (segment_bytes) {
                            if (cblk->modes & HT_MIXED) {
                                cblk->ht_plhd = HT_PLHD_OFF;
                                cblk->modes &= (uint8_t) (~(JPEG2000_CTSY_HTJ2K_F));
                            }
                            else {
                                av_log(s->avctx, AV_LOG_WARNING, "Length information for a HT-codeblock is invalid\n");
                            }
                        }
                    } else {
                        while (pass_bound <= segment_passes) {
                            bits_to_read++;
                            pass_bound += pass_bound;
                        }
                        segment_bytes = get_bits(s, bits_to_read);
                        if (segment_bytes) {
                            // No more placeholder passes
                            if (!(cblk->modes & HT_MIXED)) {
                                // Must be the first HT Cleanup pass
                                if (segment_bytes < 2)
                                    av_log(s->avctx, AV_LOG_WARNING, "Length information for a HT-codeblock is invalid\n");
                                next_segment_passes = 2;
                                cblk->ht_plhd = HT_PLHD_OFF;
                                // Write length information for HT CleanUp segment
                                cblk->pass_lengths[0] = segment_bytes;
                            } else if (cblk->lblock > 3 && segment_bytes > 1
                                       && (segment_bytes >> (bits_to_read - 1)) == 0) {
                                // Must be the first HT Cleanup pass, since length MSB is 0
                                next_segment_passes = 2;
                                cblk->ht_plhd = HT_PLHD_OFF;
                                // Write length information for HT CleanUp segment
                                cblk->pass_lengths[0] = segment_bytes;
                            } else {
                                // Must have an original (non-HT) block coding pass
                                cblk->modes &= (uint8_t) (~(JPEG2000_CTSY_HTJ2K_F));
                                cblk->ht_plhd = HT_PLHD_OFF;
                                segment_passes = newpasses;
                                while (pass_bound <= segment_passes) {
                                    bits_to_read++;
                                    pass_bound += pass_bound;
                                    segment_bytes <<= 1;
                                    segment_bytes += get_bits(s, 1);
                                }
                            }
                        } else {
                            // Probably parsing placeholder passes, but we need to read an
                            // extra length bit to verify this, since prior to the first
                            // HT Cleanup pass, the number of length bits read for a
                            // contributing code-block is dependent on the number of passes
                            // being included, as if it were a non-HT code-block.
                            segment_passes = newpasses;
                            if (pass_bound <= segment_passes) {
                                while (1) {
                                    bits_to_read++;
                                    pass_bound += pass_bound;
                                    segment_bytes <<= 1;
                                    segment_bytes += get_bits(s, 1);
                                    if (pass_bound > segment_passes)
                                        break;
                                }
                                if (segment_bytes) {
                                    if (cblk->modes & HT_MIXED) {
                                        cblk->modes &= (uint8_t) (~(JPEG2000_CTSY_HTJ2K_F));
                                        cblk->ht_plhd = HT_PLHD_OFF;
                                    } else {
                                        av_log(s->avctx, AV_LOG_WARNING, "Length information for a HT-codeblock is invalid\n");
                                    }
                                }
                            }
                        }
                    }
                } else if (cblk->modes & JPEG2000_CTSY_HTJ2K_F) {
                    // Quality layer commences with a non-initial HT coding pass
                    if(bits_to_read != 0)
                        av_log(s->avctx, AV_LOG_WARNING, "Length information for a HT-codeblock is invalid\n");
                    segment_passes = cblk->npasses % 3;
                    if (segment_passes == 0) {
                        // newpasses is a HT Cleanup pass; next segment has refinement passes
                        segment_passes = 1;
                        next_segment_passes = 2;
                        if (segment_bytes == 1)
                            av_log(s->avctx, AV_LOG_WARNING, "Length information for a HT-codeblock is invalid\n");
                    } else {
                        // newpasses = 1 means npasses is HT SigProp; 2 means newpasses is
                        // HT MagRef pass
                        segment_passes = newpasses > 1 ? 3 - segment_passes : 1;
                        next_segment_passes = 1;
                        bits_to_read = av_log2(segment_passes);
                    }
                    bits_to_read = (uint8_t) (bits_to_read + cblk->lblock);
                    segment_bytes = get_bits(s, bits_to_read);
                    // Write length information for HT Refinement segment
                    cblk->pass_lengths[1] += segment_bytes;
                } else if (!(cblk->modes & (JPEG2000_CBLK_TERMALL | JPEG2000_CBLK_BYPASS))) {
                    // Common case for non-HT code-blocks; we have only one segment
                    bits_to_read = (uint8_t) cblk->lblock + av_log2((uint8_t) newpasses);
                    segment_bytes = get_bits(s, bits_to_read);
                    segment_passes = newpasses;
                } else if (cblk->modes & JPEG2000_CBLK_TERMALL) {
                    // RESTART MODE
                    bits_to_read = cblk->lblock;
                    segment_bytes = get_bits(s, bits_to_read);
                    segment_passes = 1;
                    next_segment_passes = 1;
                } else {
                    // BYPASS MODE
                    bypass_term_threshold = 10;
                    if(bits_to_read != 0)
                        av_log(s->avctx, AV_LOG_WARNING, "Length information for a codeblock is invalid\n");
                    if (cblk->npasses < bypass_term_threshold) {
                        // May have from 1 to 10 uninterrupted passes before 1st RAW SigProp
                        segment_passes = bypass_term_threshold - cblk->npasses;
                        if (segment_passes > newpasses)
                            segment_passes = newpasses;
                        while ((2 << bits_to_read) <= segment_passes)
                            bits_to_read++;
                        next_segment_passes = 2;
                    } else if ((cblk->npasses - bypass_term_threshold) % 3 < 2) {
                        // 0 means newpasses is a RAW SigProp; 1 means newpasses is a RAW MagRef pass
                        segment_passes = newpasses > 1 ? 2 - (cblk->npasses - bypass_term_threshold) % 3 : 1;
                        bits_to_read = av_log2(segment_passes);
                        next_segment_passes = 1;
                    } else {
                        // newpasses is an isolated Cleanup pass that precedes a RAW SigProp pass
                        segment_passes = 1;
                        next_segment_passes = 2;
                    }
                    bits_to_read = (uint8_t) (bits_to_read + cblk->lblock);
                    segment_bytes = get_bits(s, bits_to_read);
                }
                // Update cblk->npasses and write length information
                cblk->npasses = (uint8_t) (cblk->npasses + segment_passes);
                cblk->lengthinc[cblk->nb_lengthinc++] = segment_bytes;

                if ((cblk->modes & JPEG2000_CTSY_HTJ2K_F) && cblk->ht_plhd == HT_PLHD_OFF) {
                    newpasses -= (uint8_t) segment_passes;
                    while (newpasses > 0) {
                        segment_passes = newpasses > 1 ? next_segment_passes : 1;
                        next_segment_passes = (uint8_t) (3 - next_segment_passes);
                        bits_to_read = (uint8_t) (cblk->lblock + av_log2(segment_passes));
                        segment_bytes = get_bits(s, bits_to_read);
                        newpasses -= (uint8_t) (segment_passes);
                        // This is a FAST Refinement pass
                        // Write length information for HT Refinement segment
                        cblk->pass_lengths[1] += segment_bytes;
                        // Update cblk->npasses and write length information
                        cblk->npasses = (uint8_t) (cblk->npasses + segment_passes);
                        cblk->lengthinc[cblk->nb_lengthinc++] = segment_bytes;
                    }
                } else {
                    newpasses -= (uint8_t) (segment_passes);
                    while (newpasses > 0) {
                        if (bypass_term_threshold != 0) {
                            segment_passes = newpasses > 1 ? next_segment_passes : 1;
                            next_segment_passes = (uint8_t) (3 - next_segment_passes);
                            bits_to_read = (uint8_t) (cblk->lblock + av_log2(segment_passes));
                        } else {
                            if ((cblk->modes & JPEG2000_CBLK_TERMALL) == 0)
                                av_log(s->avctx, AV_LOG_WARNING, "Corrupted packet header is found.\n");
                            segment_passes = 1;
                            bits_to_read = cblk->lblock;
                        }
                        segment_bytes = get_bits(s, bits_to_read);
                        newpasses -= (uint8_t) (segment_passes);

                        // Update cblk->npasses and write length information
                        cblk->npasses = (uint8_t) (cblk->npasses + segment_passes);
                        cblk->lengthinc[cblk->nb_lengthinc++] = segment_bytes;
                    }
                }

                for (int i = 0; i < cblk->nb_lengthinc; ++i)
                    tmp_length = (tmp_length < cblk->lengthinc[i]) ? cblk->lengthinc[i] : tmp_length;

                if (tmp_length > cblk->data_allocated) {
                    size_t new_size = FFMAX(2 * cblk->data_allocated, tmp_length);
                    void *new = av_realloc(cblk->data, new_size);
                    if (new) {
                        cblk->data = new;
                        cblk->data_allocated = new_size;
                    }
                }
                if (tmp_length > cblk->data_allocated) {
                    avpriv_request_sample(s->avctx,
                                        "Block with lengthinc greater than %"SIZE_SPECIFIER"",
                                        cblk->data_allocated);
                    return AVERROR_PATCHWELCOME;
                }
            } else {
                // This codeblock has no contribution to the current packet
                continue;
            }
        }
    }
    jpeg2000_flush(s);

    if (codsty->csty & JPEG2000_CSTY_EPH) {
        if (bytestream2_peek_be16(&s->g) == JPEG2000_EPH)
            bytestream2_skip(&s->g, 2);
        else
            av_log(s->avctx, AV_LOG_ERROR, "EPH marker not found. instead %X\n", bytestream2_peek_be32(&s->g));
    }

    // Save state of stream
    if (s->has_ppm) {
        tile->tile_part[*tp_index].header_tpg = s->g;
        select_stream(s, tile, tp_index, codsty);
    } else if (tile->has_ppt) {
        tile->packed_headers_stream = s->g;
        select_stream(s, tile, tp_index, codsty);
    }
    for (bandno = 0; bandno < rlevel->nbands; bandno++) {
        Jpeg2000Band *band = rlevel->band + bandno;
        Jpeg2000Prec *prec = band->prec + precno;

        nb_code_blocks = prec->nb_codeblocks_height * prec->nb_codeblocks_width;
        for (cblkno = 0; cblkno < nb_code_blocks; cblkno++) {
            Jpeg2000Cblk *cblk = prec->cblk + cblkno;
            if (!cblk->nb_terminationsinc && !cblk->lengthinc)
                continue;
            for (cwsno = 0; cwsno < cblk->nb_lengthinc; cwsno ++) {
                if (cblk->data_allocated < cblk->length + cblk->lengthinc[cwsno] + 4) {
                    size_t new_size = FFMAX(2*cblk->data_allocated, cblk->length + cblk->lengthinc[cwsno] + 4);
                    void *new = av_realloc(cblk->data, new_size);
                    if (new) {
                        cblk->data = new;
                        cblk->data_allocated = new_size;
                    }
                }
                if (   bytestream2_get_bytes_left(&s->g) < cblk->lengthinc[cwsno]
                    || cblk->data_allocated < cblk->length + cblk->lengthinc[cwsno] + 4
                ) {
                    av_log(s->avctx, AV_LOG_ERROR,
                        "Block length %"PRIu16" or lengthinc %d is too large, left %d\n",
                        cblk->length, cblk->lengthinc[cwsno], bytestream2_get_bytes_left(&s->g));
                    return AVERROR_INVALIDDATA;
                }

                bytestream2_get_bufferu(&s->g, cblk->data + cblk->length, cblk->lengthinc[cwsno]);
                cblk->length   += cblk->lengthinc[cwsno];
                memset(cblk->data + cblk->length, 0, 4);
                cblk->lengthinc[cwsno] = 0;
                if (cblk->nb_terminationsinc) {
                    cblk->nb_terminationsinc--;
                    cblk->nb_terminations++;
                    cblk->data[cblk->length++] = 0xFF;
                    cblk->data[cblk->length++] = 0xFF;
                    cblk->data_start[cblk->nb_terminations] = cblk->length;
                }
            }
            av_freep(&cblk->lengthinc);
            cblk->nb_lengthinc = 0;
        }
    }
    // Save state of stream
    tile->tile_part[*tp_index].tpg = s->g;
    return 0;

skip_data:
    if (codsty->csty & JPEG2000_CSTY_EPH) {
        if (bytestream2_peek_be16(&s->g) == JPEG2000_EPH)
            bytestream2_skip(&s->g, 2);
        else
            av_log(s->avctx, AV_LOG_ERROR, "EPH marker not found. instead %X\n", bytestream2_peek_be32(&s->g));
    }
    if (s->has_ppm) {
        tile->tile_part[*tp_index].header_tpg = s->g;
        select_stream(s, tile, tp_index, codsty);
    } else if (tile->has_ppt) {
        tile->packed_headers_stream = s->g;
        select_stream(s, tile, tp_index, codsty);
    }
    tile->tile_part[*tp_index].tpg = s->g;
    return 0;
}

static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
                                             int RSpoc, int CSpoc,
                                             int LYEpoc, int REpoc, int CEpoc,
                                             int Ppoc, int *tp_index)
{
    int ret = 0;
    int layno, reslevelno, compno, precno, ok_reslevel;
    int x, y;
    int step_x, step_y;

    switch (Ppoc) {
    case JPEG2000_PGOD_RLCP:
        av_log(s->avctx, AV_LOG_DEBUG, "Progression order RLCP\n");
        ok_reslevel = 1;
        for (reslevelno = RSpoc; ok_reslevel && reslevelno < REpoc; reslevelno++) {
            ok_reslevel = 0;
            for (layno = 0; layno < LYEpoc; layno++) {
                for (compno = CSpoc; compno < CEpoc; compno++) {
                    Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                    Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
                    if (reslevelno < codsty->nreslevels) {
                        Jpeg2000ResLevel *rlevel = tile->comp[compno].reslevel +
                                                reslevelno;
                        ok_reslevel = 1;
                        for (precno = 0; precno < rlevel->num_precincts_x * rlevel->num_precincts_y; precno++)
                            if ((ret = jpeg2000_decode_packet(s, tile, tp_index,
                                                              codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_LRCP:
        av_log(s->avctx, AV_LOG_DEBUG, "Progression order LRCP\n");
        for (layno = 0; layno < LYEpoc; layno++) {
            ok_reslevel = 1;
            for (reslevelno = RSpoc; ok_reslevel && reslevelno < REpoc; reslevelno++) {
                ok_reslevel = 0;
                for (compno = CSpoc; compno < CEpoc; compno++) {
                    Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                    Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
                    if (reslevelno < codsty->nreslevels) {
                        Jpeg2000ResLevel *rlevel = tile->comp[compno].reslevel +
                                                reslevelno;
                        ok_reslevel = 1;
                        for (precno = 0; precno < rlevel->num_precincts_x * rlevel->num_precincts_y; precno++)
                            if ((ret = jpeg2000_decode_packet(s, tile, tp_index,
                                                              codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_CPRL:
        av_log(s->avctx, AV_LOG_DEBUG, "Progression order CPRL\n");
        for (compno = CSpoc; compno < CEpoc; compno++) {
            Jpeg2000Component *comp     = tile->comp + compno;
            Jpeg2000CodingStyle *codsty = tile->codsty + compno;
            Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
            step_x = 32;
            step_y = 32;

            if (RSpoc >= FFMIN(codsty->nreslevels, REpoc))
                continue;

            for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                step_x = FFMIN(step_x, rlevel->log2_prec_width  + reducedresno);
                step_y = FFMIN(step_y, rlevel->log2_prec_height + reducedresno);
            }
            if (step_x >= 31 || step_y >= 31){
                avpriv_request_sample(s->avctx, "CPRL with large step");
                return AVERROR_PATCHWELCOME;
            }
            step_x = 1<<step_x;
            step_y = 1<<step_y;

            for (y = tile->coord[1][0]; y < tile->coord[1][1]; y = (y/step_y + 1)*step_y) {
                for (x = tile->coord[0][0]; x < tile->coord[0][1]; x = (x/step_x + 1)*step_x) {
                    for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                        unsigned prcx, prcy;
                        uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                        Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                        int xc = x / s->cdx[compno];
                        int yc = y / s->cdy[compno];

                        if (yc % (1LL << (rlevel->log2_prec_height + reducedresno)) && y != tile->coord[1][0]) //FIXME this is a subset of the check
                            continue;

                        if (xc % (1LL << (rlevel->log2_prec_width + reducedresno)) && x != tile->coord[0][0]) //FIXME this is a subset of the check
                            continue;

                        // check if a precinct exists
                        prcx   = ff_jpeg2000_ceildivpow2(xc, reducedresno) >> rlevel->log2_prec_width;
                        prcy   = ff_jpeg2000_ceildivpow2(yc, reducedresno) >> rlevel->log2_prec_height;
                        prcx  -= ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], reducedresno) >> rlevel->log2_prec_width;
                        prcy  -= ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], reducedresno) >> rlevel->log2_prec_height;

                        precno = prcx + rlevel->num_precincts_x * prcy;

                        if (prcx >= rlevel->num_precincts_x || prcy >= rlevel->num_precincts_y) {
                            av_log(s->avctx, AV_LOG_WARNING, "prc %d %d outside limits %d %d\n",
                                   prcx, prcy, rlevel->num_precincts_x, rlevel->num_precincts_y);
                            continue;
                        }

                        for (layno = 0; layno < LYEpoc; layno++) {
                            if ((ret = jpeg2000_decode_packet(s, tile, tp_index, codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                        }
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_RPCL:
        av_log(s->avctx, AV_LOG_WARNING, "Progression order RPCL\n");
        ok_reslevel = 1;
        for (reslevelno = RSpoc; ok_reslevel && reslevelno < REpoc; reslevelno++) {
            ok_reslevel = 0;
            step_x = 30;
            step_y = 30;
            for (compno = CSpoc; compno < CEpoc; compno++) {
                Jpeg2000Component *comp     = tile->comp + compno;
                Jpeg2000CodingStyle *codsty = tile->codsty + compno;

                if (reslevelno < codsty->nreslevels) {
                    uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                    Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                    step_x = FFMIN(step_x, rlevel->log2_prec_width  + reducedresno);
                    step_y = FFMIN(step_y, rlevel->log2_prec_height + reducedresno);
                }
            }
            step_x = 1<<step_x;
            step_y = 1<<step_y;

            for (y = tile->coord[1][0]; y < tile->coord[1][1]; y = (y/step_y + 1)*step_y) {
                for (x = tile->coord[0][0]; x < tile->coord[0][1]; x = (x/step_x + 1)*step_x) {
                    for (compno = CSpoc; compno < CEpoc; compno++) {
                        Jpeg2000Component *comp     = tile->comp + compno;
                        Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                        Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
                        uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                        Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                        unsigned prcx, prcy;
                        int trx0, try0;

                        if (!s->cdx[compno] || !s->cdy[compno])
                            return AVERROR_INVALIDDATA;

                        if (reslevelno >= codsty->nreslevels)
                            continue;

                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], (int64_t)s->cdx[compno] << reducedresno);
                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], (int64_t)s->cdy[compno] << reducedresno);

                        if (!(y % ((uint64_t)s->cdy[compno] << (rlevel->log2_prec_height + reducedresno)) == 0 ||
                             (y == tile->coord[1][0] && ((int64_t)try0 << reducedresno) % (1ULL << (reducedresno + rlevel->log2_prec_height)))))
                            continue;

                        if (!(x % ((uint64_t)s->cdx[compno] << (rlevel->log2_prec_width + reducedresno)) == 0 ||
                             (x == tile->coord[0][0] && ((int64_t)trx0 << reducedresno) % (1ULL << (reducedresno + rlevel->log2_prec_width)))))
                            continue;

                        // check if a precinct exists
                        prcx   = ff_jpeg2000_ceildiv(x, (int64_t)s->cdx[compno] << reducedresno) >> rlevel->log2_prec_width;
                        prcy   = ff_jpeg2000_ceildiv(y, (int64_t)s->cdy[compno] << reducedresno) >> rlevel->log2_prec_height;
                        prcx  -= ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], reducedresno) >> rlevel->log2_prec_width;
                        prcy  -= ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], reducedresno) >> rlevel->log2_prec_height;

                        precno = prcx + rlevel->num_precincts_x * prcy;

                        ok_reslevel = 1;
                        if (prcx >= rlevel->num_precincts_x || prcy >= rlevel->num_precincts_y) {
                            av_log(s->avctx, AV_LOG_WARNING, "prc %d %d outside limits %d %d\n",
                                   prcx, prcy, rlevel->num_precincts_x, rlevel->num_precincts_y);
                            continue;
                        }

                        for (layno = 0; layno < LYEpoc; layno++) {
                            if ((ret = jpeg2000_decode_packet(s, tile, tp_index,
                                                              codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                        }
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_PCRL:
        av_log(s->avctx, AV_LOG_WARNING, "Progression order PCRL\n");
        step_x = 32;
        step_y = 32;
        for (compno = CSpoc; compno < CEpoc; compno++) {
            Jpeg2000Component *comp     = tile->comp + compno;
            Jpeg2000CodingStyle *codsty = tile->codsty + compno;

            for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                step_x = FFMIN(step_x, rlevel->log2_prec_width  + reducedresno);
                step_y = FFMIN(step_y, rlevel->log2_prec_height + reducedresno);
            }
        }
        if (step_x >= 31 || step_y >= 31){
            avpriv_request_sample(s->avctx, "PCRL with large step");
            return AVERROR_PATCHWELCOME;
        }
        step_x = 1<<step_x;
        step_y = 1<<step_y;

        for (y = tile->coord[1][0]; y < tile->coord[1][1]; y = (y/step_y + 1)*step_y) {
            for (x = tile->coord[0][0]; x < tile->coord[0][1]; x = (x/step_x + 1)*step_x) {
                for (compno = CSpoc; compno < CEpoc; compno++) {
                    Jpeg2000Component *comp     = tile->comp + compno;
                    Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                    Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;

                    if (!s->cdx[compno] || !s->cdy[compno])
                        return AVERROR_INVALIDDATA;

                    for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                        unsigned prcx, prcy;
                        uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                        Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                        int trx0, try0;

                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], (int64_t)s->cdx[compno] << reducedresno);
                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], (int64_t)s->cdy[compno] << reducedresno);

                        if (!(y % ((uint64_t)s->cdy[compno] << (rlevel->log2_prec_height + reducedresno)) == 0 ||
                             (y == tile->coord[1][0] && ((int64_t)try0 << reducedresno) % (1ULL << (reducedresno + rlevel->log2_prec_height)))))
                             continue;

                        if (!(x % ((uint64_t)s->cdx[compno] << (rlevel->log2_prec_width + reducedresno)) == 0 ||
                             (x == tile->coord[0][0] && ((int64_t)trx0 << reducedresno) % (1ULL << (reducedresno + rlevel->log2_prec_width)))))
                             continue;

                        // check if a precinct exists
                        prcx   = ff_jpeg2000_ceildiv(x, (int64_t)s->cdx[compno] << reducedresno) >> rlevel->log2_prec_width;
                        prcy   = ff_jpeg2000_ceildiv(y, (int64_t)s->cdy[compno] << reducedresno) >> rlevel->log2_prec_height;
                        prcx  -= ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], reducedresno) >> rlevel->log2_prec_width;
                        prcy  -= ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], reducedresno) >> rlevel->log2_prec_height;

                        precno = prcx + rlevel->num_precincts_x * prcy;

                        if (prcx >= rlevel->num_precincts_x || prcy >= rlevel->num_precincts_y) {
                            av_log(s->avctx, AV_LOG_WARNING, "prc %d %d outside limits %d %d\n",
                                   prcx, prcy, rlevel->num_precincts_x, rlevel->num_precincts_y);
                            continue;
                        }

                        for (layno = 0; layno < LYEpoc; layno++) {
                            if ((ret = jpeg2000_decode_packet(s, tile, tp_index, codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                        }
                    }
                }
            }
        }
        break;

    default:
        break;
    }

    return ret;
}

static int jpeg2000_decode_packets(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int ret = AVERROR_BUG;
    int i;
    int tp_index = 0;

    s->bit_index = 8;
    if (tile->poc.nb_poc) {
        for (i=0; i<tile->poc.nb_poc; i++) {
            Jpeg2000POCEntry *e = &tile->poc.poc[i];
            ret = jpeg2000_decode_packets_po_iteration(s, tile,
                e->RSpoc, e->CSpoc,
                FFMIN(e->LYEpoc, tile->codsty[0].nlayers),
                e->REpoc,
                FFMIN(e->CEpoc, s->ncomponents),
                e->Ppoc, &tp_index
                );
            if (ret < 0)
                return ret;
        }
    } else {
        ret = jpeg2000_decode_packets_po_iteration(s, tile,
            0, 0,
            tile->codsty[0].nlayers,
            33,
            s->ncomponents,
            tile->codsty[0].prog_order,
            &tp_index
        );
    }
    /* EOC marker reached */
    bytestream2_skip(&s->g, 2);

    return ret;
}

/* TIER-1 routines */
static void decode_sigpass(Jpeg2000T1Context *t1, int width, int height,
                           int bpno, int bandno,
                           int vert_causal_ctx_csty_symbol)
{
    int mask = 3 << (bpno - 1), y0, x, y;

    for (y0 = 0; y0 < height; y0 += 4)
        for (x = 0; x < width; x++)
            for (y = y0; y < height && y < y0 + 4; y++) {
                int flags_mask = -1;
                if (vert_causal_ctx_csty_symbol && y == y0 + 3)
                    flags_mask &= ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE | JPEG2000_T1_SGN_S);
                if ((t1->flags[(y+1) * t1->stride + x+1] & JPEG2000_T1_SIG_NB & flags_mask)
                && !(t1->flags[(y+1) * t1->stride + x+1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS))) {
                    if (ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ff_jpeg2000_getsigctxno(t1->flags[(y+1) * t1->stride + x+1] & flags_mask, bandno))) {
                        int xorbit, ctxno = ff_jpeg2000_getsgnctxno(t1->flags[(y+1) * t1->stride + x+1] & flags_mask, &xorbit);
                        if (t1->mqc.raw) {
                            t1->data[(y) * t1->stride + x] |= (uint32_t)(ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno)) << 31;
                            t1->data[(y) * t1->stride + x] |= mask;
                        } else {
                            t1->data[(y) * t1->stride + x] |= (uint32_t)(ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno) ^ xorbit) << 31;
                            t1->data[(y) * t1->stride + x] |= mask;
                        }
                        ff_jpeg2000_set_significance(t1, x, y,
                                                     t1->data[(y) * t1->stride + x] & INT32_MIN);
                    }
                    t1->flags[(y + 1) * t1->stride + x + 1] |= JPEG2000_T1_VIS;
                }
            }
}

static void decode_refpass(Jpeg2000T1Context *t1, int width, int height,
                           int bpno, int vert_causal_ctx_csty_symbol)
{
    int phalf;
    int y0, x, y;

    phalf = 1 << (bpno - 1);

    for (y0 = 0; y0 < height; y0 += 4)
        for (x = 0; x < width; x++)
            for (y = y0; y < height && y < y0 + 4; y++)
                if ((t1->flags[(y + 1) * t1->stride + x + 1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS)) == JPEG2000_T1_SIG) {
                    int flags_mask = (vert_causal_ctx_csty_symbol && y == y0 + 3) ?
                        ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE | JPEG2000_T1_SGN_S) : -1;
                    int ctxno = ff_jpeg2000_getrefctxno(t1->flags[(y + 1) * t1->stride + x + 1] & flags_mask);
                    t1->data[(y) * t1->stride + x] |= phalf;
                    if (ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno))
                        t1->data[(y) * t1->stride + x] |= phalf << 1;
                    else {
                        t1->data[(y) * t1->stride + x] &= ~(phalf << 1);

                    }
                    t1->flags[(y + 1) * t1->stride + x + 1] |= JPEG2000_T1_REF;
                }
}

static void decode_clnpass(const Jpeg2000DecoderContext *s, Jpeg2000T1Context *t1,
                           int width, int height, int bpno, int bandno,
                           int seg_symbols, int vert_causal_ctx_csty_symbol)
{
    int mask = 3 << (bpno - 1), y0, x, y, runlen, dec;

    for (y0 = 0; y0 < height; y0 += 4) {
        for (x = 0; x < width; x++) {
            int flags_mask = -1;
            if (vert_causal_ctx_csty_symbol)
                flags_mask &= ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE | JPEG2000_T1_SGN_S);
            if (y0 + 3 < height &&
                !((t1->flags[(y0 + 1) * t1->stride + x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[(y0 + 2) * t1->stride + x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[(y0 + 3) * t1->stride + x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[(y0 + 4) * t1->stride + x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG) & flags_mask))) {
                if (!ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_RL))
                    continue;
                runlen = ff_mqc_decode(&t1->mqc,
                                       t1->mqc.cx_states + MQC_CX_UNI);
                runlen = (runlen << 1) | ff_mqc_decode(&t1->mqc,
                                                       t1->mqc.cx_states +
                                                       MQC_CX_UNI);
                dec = 1;
            } else {
                runlen = 0;
                dec    = 0;
            }

            for (y = y0 + runlen; y < y0 + 4 && y < height; y++) {
                int flags_mask = -1;
                if (vert_causal_ctx_csty_symbol && y == y0 + 3)
                    flags_mask &= ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE | JPEG2000_T1_SGN_S);
                if (!dec) {
                    if (!(t1->flags[(y+1) * t1->stride + x+1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS))) {
                        dec = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ff_jpeg2000_getsigctxno(t1->flags[(y+1) * t1->stride + x+1] & flags_mask,
                                                                                             bandno));
                    }
                }
                if (dec) {
                    int xorbit;
                    int ctxno = ff_jpeg2000_getsgnctxno(t1->flags[(y + 1) * t1->stride + x + 1] & flags_mask,
                                                        &xorbit);
                    t1->data[(y) * t1->stride + x] |= (uint32_t)(ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno) ^ xorbit) << 31;
                    t1->data[(y) * t1->stride + x] |= mask;
                    ff_jpeg2000_set_significance(t1, x, y, t1->data[(y) * t1->stride + x] & INT32_MIN);
                }
                dec = 0;
                t1->flags[(y + 1) * t1->stride + x + 1] &= ~JPEG2000_T1_VIS;
            }
        }
    }
    if (seg_symbols) {
        int val;
        val = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        if (val != 0xa)
            av_log(s->avctx, AV_LOG_ERROR,
                   "Segmentation symbol value incorrect\n");
    }
}

static int decode_cblk(const Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *codsty,
                       Jpeg2000T1Context *t1, Jpeg2000Cblk *cblk,
                       int width, int height, int bandpos, uint8_t roi_shift, const int M_b)
{
    int passno = cblk->npasses, pass_t = 2, bpno = cblk->nonzerobits - 1 + 31 - M_b - 1 - roi_shift;
    int pass_cnt = 0;
    int vert_causal_ctx_csty_symbol = codsty->cblk_style & JPEG2000_CBLK_VSC;
    int term_cnt = 0;
    int coder_type;

    av_assert0(width <= 1024U && height <= 1024U);
    av_assert0(width*height <= 4096);

    memset(t1->data, 0, t1->stride * height * sizeof(*t1->data));

    /* If code-block contains no compressed data: nothing to do. */
    if (!cblk->length)
        return 0;

    memset(t1->flags, 0, t1->stride * (height + 2) * sizeof(*t1->flags));

    cblk->data[cblk->length] = 0xff;
    cblk->data[cblk->length+1] = 0xff;
    ff_mqc_initdec(&t1->mqc, cblk->data, 0, 1);

    while (passno--) {
        if (bpno < 0 || bpno > 29) {
            av_log(s->avctx, AV_LOG_ERROR, "bpno became invalid\n");
            return AVERROR_INVALIDDATA;
        }
        switch(pass_t) {
        case 0:
            decode_sigpass(t1, width, height, bpno + 1, bandpos,
                           vert_causal_ctx_csty_symbol);
            break;
        case 1:
            decode_refpass(t1, width, height, bpno + 1, vert_causal_ctx_csty_symbol);
            break;
        case 2:
            av_assert2(!t1->mqc.raw);
            decode_clnpass(s, t1, width, height, bpno + 1, bandpos,
                           codsty->cblk_style & JPEG2000_CBLK_SEGSYM,
                           vert_causal_ctx_csty_symbol);
            break;
        }
        if (codsty->cblk_style & JPEG2000_CBLK_RESET) // XXX no testcase for just this
            ff_mqc_init_contexts(&t1->mqc);

        if (passno && (coder_type = needs_termination(codsty->cblk_style, pass_cnt))) {
            if (term_cnt >= cblk->nb_terminations) {
                av_log(s->avctx, AV_LOG_ERROR, "Missing needed termination \n");
                return AVERROR_INVALIDDATA;
            }
            if (FFABS(cblk->data + cblk->data_start[term_cnt + 1] - 2 - t1->mqc.bp) > 0) {
                av_log(s->avctx, AV_LOG_WARNING, "Mid mismatch %"PTRDIFF_SPECIFIER" in pass %d of %d\n",
                    cblk->data + cblk->data_start[term_cnt + 1] - 2 - t1->mqc.bp,
                    pass_cnt, cblk->npasses);
            }

            ff_mqc_initdec(&t1->mqc, cblk->data + cblk->data_start[++term_cnt], coder_type == 2, 0);
        }

        pass_t++;
        if (pass_t == 3) {
            bpno--;
            pass_t = 0;
        }
        pass_cnt ++;
    }

    if (cblk->data + cblk->length - 2 > t1->mqc.bp) {
        av_log(s->avctx, AV_LOG_WARNING, "End mismatch %"PTRDIFF_SPECIFIER"\n",
               cblk->data + cblk->length - 2 - t1->mqc.bp);
    }

    if (cblk->data + cblk->length < t1->mqc.bp) {
        av_log(s->avctx, AV_LOG_WARNING, "Synthetic End of Stream Marker Read.\n");
    }

    /* Reconstruct the sample values */
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int32_t sign, n, val;
            const uint32_t mask  = UINT32_MAX >> (M_b + 1); // bit mask for ROI detection

            n = x + (y * t1->stride);
            val = t1->data[n];
            sign = val & INT32_MIN;
            val &= INT32_MAX;
            /* ROI shift, if necessary */
            if (roi_shift && (((uint32_t)val & ~mask) == 0))
                val <<= roi_shift;
            t1->data[n] = val | sign; /* NOTE: Binary point for reconstruction value is located in 31 - M_b */
        }
    }
    return 1;
}

/* TODO: Verify dequantization for lossless case
 * comp->data can be float or int
 * band->stepsize can be float or int
 * depending on the type of DWT transformation.
 * see ISO/IEC 15444-1:2002 A.6.1 */

/* Float dequantization of a codeblock.*/
static void dequantization_float(int x, int y, Jpeg2000Cblk *cblk,
                                 Jpeg2000Component *comp,
                                 Jpeg2000T1Context *t1, Jpeg2000Band *band, const int M_b)
{
    int i, j;
    int w = cblk->coord[0][1] - cblk->coord[0][0];
    const int downshift = 31 - M_b;
    float fscale = band->f_stepsize;
    fscale /= (float)(1 << downshift);
    for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
        float *datap = &comp->f_data[(comp->coord[0][1] - comp->coord[0][0]) * (y + j) + x];
        int *src = t1->data + j*t1->stride;
        for (i = 0; i < w; ++i) {
            int val = src[i];
            if (val < 0) // Convert sign-magnitude to two's complement
                val = -(val & INT32_MAX);
            datap[i] = (float)val * fscale;
        }
    }
}

/* Integer dequantization of a codeblock.*/
static void dequantization_int(int x, int y, Jpeg2000Cblk *cblk,
                               Jpeg2000Component *comp,
                               Jpeg2000T1Context *t1, Jpeg2000Band *band, const int M_b)
{
    int i, j;
    const int downshift = 31 - M_b;
    int w = cblk->coord[0][1] - cblk->coord[0][0];
    for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
        int32_t *datap = &comp->i_data[(comp->coord[0][1] - comp->coord[0][0]) * (y + j) + x];
        int *src = t1->data + j*t1->stride;
        if (band->i_stepsize == 32768) {
            for (i = 0; i < w; ++i) {
                int val = src[i];
                if (val < 0)  // Convert sign-magnitude to two's complement
                    val = -((val & INT32_MAX) >> downshift);
                else
                    val >>= downshift;
                datap[i] = val;
            }
        } else {
            // This should be VERY uncommon
            for (i = 0; i < w; ++i) {
                int val = src[i];
                if (val < 0)  // Convert sign-magnitude to two's complement
                    val = -((val & INT32_MAX) >> downshift);
                else
                    val >>= downshift;
                datap[i] = (val * (int64_t)band->i_stepsize) / 65536;
            }
        }
    }
}

static void dequantization_int_97(int x, int y, Jpeg2000Cblk *cblk,
                               Jpeg2000Component *comp,
                               Jpeg2000T1Context *t1, Jpeg2000Band *band, const int M_b)
{
    int i, j;
    int w = cblk->coord[0][1] - cblk->coord[0][0];
    float fscale = band->f_stepsize;
    const int downshift = 31 - M_b;
    const int PRESCALE = 6; // At least 6 is required to pass the conformance tests in ISO/IEC 15444-4
    int scale;

    fscale /= (float)(1 << downshift);
    fscale *= (float)(1 << PRESCALE);
    fscale *= (float)(1 << (16 + I_PRESHIFT));
    scale = (int)(fscale + 0.5);
    band->i_stepsize = scale;
    for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
        int32_t *datap = &comp->i_data[(comp->coord[0][1] - comp->coord[0][0]) * (y + j) + x];
        int *src = t1->data + j*t1->stride;
        for (i = 0; i < w; ++i) {
            int val = src[i];
            if (val < 0) // Convert sign-magnitude to two's complement
                val = -(val & INT32_MAX);
            // Shifting down to prevent overflow in dequantization
            val = (val + (1 << (PRESCALE - 1))) >> PRESCALE;
            datap[i] = RSHIFT(val * (int64_t)band->i_stepsize, 16);
        }
    }
}

static inline void mct_decode(const Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int i, csize = 1;
    void *src[3];

    for (i = 1; i < 3; i++) {
        if (tile->codsty[0].transform != tile->codsty[i].transform) {
            av_log(s->avctx, AV_LOG_ERROR, "Transforms mismatch, MCT not supported\n");
            return;
        }
        if (memcmp(tile->comp[0].coord, tile->comp[i].coord, sizeof(tile->comp[0].coord))) {
            av_log(s->avctx, AV_LOG_ERROR, "Coords mismatch, MCT not supported\n");
            return;
        }
    }

    for (i = 0; i < 3; i++)
        if (tile->codsty[0].transform == FF_DWT97)
            src[i] = tile->comp[i].f_data;
        else
            src[i] = tile->comp[i].i_data;

    for (i = 0; i < 2; i++)
        csize *= tile->comp[0].coord[i][1] - tile->comp[0].coord[i][0];

    s->dsp.mct_decode[tile->codsty[0].transform](src[0], src[1], src[2], csize);
}


static inline int tile_codeblocks(const Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    Jpeg2000T1Context t1;

    int compno, reslevelno, bandno;

    /* Loop on tile components */
    for (compno = 0; compno < s->ncomponents; compno++) {
        Jpeg2000Component *comp      = tile->comp   + compno;
        Jpeg2000CodingStyle *codsty  = tile->codsty + compno;
        Jpeg2000QuantStyle *quantsty = tile->qntsty + compno;

        int coded = 0;
        int subbandno = 0;

        t1.stride = (1<<codsty->log2_cblk_width) + 2;

        /* Loop on resolution levels */
        for (reslevelno = 0; reslevelno < codsty->nreslevels2decode; reslevelno++) {
            Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
            /* Loop on bands */
            for (bandno = 0; bandno < rlevel->nbands; bandno++, subbandno++) {
                int nb_precincts, precno;
                Jpeg2000Band *band = rlevel->band + bandno;
                int cblkno = 0, bandpos;
                /* See Rec. ITU-T T.800, Equation E-2 */
                int M_b = quantsty->expn[subbandno] + quantsty->nguardbits - 1;

                bandpos = bandno + (reslevelno > 0);

                if (band->coord[0][0] == band->coord[0][1] ||
                    band->coord[1][0] == band->coord[1][1])
                    continue;

                if ((codsty->cblk_style & JPEG2000_CTSY_HTJ2K_F) && M_b >= 31) {
                    avpriv_request_sample(s->avctx, "JPEG2000_CTSY_HTJ2K_F and M_b >= 31");
                    return AVERROR_PATCHWELCOME;
                }

                nb_precincts = rlevel->num_precincts_x * rlevel->num_precincts_y;
                /* Loop on precincts */
                for (precno = 0; precno < nb_precincts; precno++) {
                    Jpeg2000Prec *prec = band->prec + precno;

                    /* Loop on codeblocks */
                    for (cblkno = 0;
                         cblkno < prec->nb_codeblocks_width * prec->nb_codeblocks_height;
                         cblkno++) {
                        int x, y, ret;

                        Jpeg2000Cblk *cblk = prec->cblk + cblkno;

                        if (cblk->modes & JPEG2000_CTSY_HTJ2K_F)
                            ret = ff_jpeg2000_decode_htj2k(s, codsty, &t1, cblk,
                                                           cblk->coord[0][1] - cblk->coord[0][0],
                                                           cblk->coord[1][1] - cblk->coord[1][0],
                                                           M_b, comp->roi_shift);
                        else
                            ret = decode_cblk(s, codsty, &t1, cblk,
                                              cblk->coord[0][1] - cblk->coord[0][0],
                                              cblk->coord[1][1] - cblk->coord[1][0],
                                              bandpos, comp->roi_shift, M_b);

                        if (ret)
                            coded = 1;
                        else
                            continue;
                        x = cblk->coord[0][0] - band->coord[0][0];
                        y = cblk->coord[1][0] - band->coord[1][0];

                        if (codsty->transform == FF_DWT97)
                            dequantization_float(x, y, cblk, comp, &t1, band, M_b);
                        else if (codsty->transform == FF_DWT97_INT)
                            dequantization_int_97(x, y, cblk, comp, &t1, band, M_b);
                        else
                            dequantization_int(x, y, cblk, comp, &t1, band, M_b);
                   } /* end cblk */
                } /*end prec */
            } /* end band */
        } /* end reslevel */

        /* inverse DWT */
        if (coded)
            ff_dwt_decode(&comp->dwt, codsty->transform == FF_DWT97 ? (void*)comp->f_data : (void*)comp->i_data);

    } /*end comp */
    return 0;
}

#define WRITE_FRAME(D, PIXEL)                                                                     \
    static inline void write_frame_ ## D(const Jpeg2000DecoderContext * s, Jpeg2000Tile * tile,   \
                                         AVFrame * picture, int precision)                        \
    {                                                                                             \
        const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(s->avctx->pix_fmt);               \
        int planar    = !!(pixdesc->flags & AV_PIX_FMT_FLAG_PLANAR);                              \
        int pixelsize = planar ? 1 : pixdesc->nb_components;                                      \
                                                                                                  \
        int compno;                                                                               \
        int x, y;                                                                                 \
                                                                                                  \
        for (compno = 0; compno < s->ncomponents; compno++) {                                     \
            Jpeg2000Component *comp     = tile->comp + compno;                                    \
            Jpeg2000CodingStyle *codsty = tile->codsty + compno;                                  \
            PIXEL *line;                                                                          \
            float *datap     = comp->f_data;                                                      \
            int32_t *i_datap = comp->i_data;                                                      \
            int cbps         = s->cbps[compno];                                                   \
            int w            = tile->comp[compno].coord[0][1] -                                   \
                               ff_jpeg2000_ceildiv(s->image_offset_x, s->cdx[compno]);            \
            int h            = tile->comp[compno].coord[1][1] -                                   \
                               ff_jpeg2000_ceildiv(s->image_offset_y, s->cdy[compno]);            \
            int plane        = 0;                                                                 \
                                                                                                  \
            if (planar)                                                                           \
                plane = s->cdef[compno] ? s->cdef[compno]-1 : (s->ncomponents-1);                 \
                                                                                                  \
            y    = tile->comp[compno].coord[1][0] -                                               \
                   ff_jpeg2000_ceildiv(s->image_offset_y, s->cdy[compno]);                        \
            line = (PIXEL *)picture->data[plane] + y * (picture->linesize[plane] / sizeof(PIXEL));\
            for (; y < h; y++) {                                                                  \
                PIXEL *dst;                                                                       \
                                                                                                  \
                x   = tile->comp[compno].coord[0][0] -                                            \
                      ff_jpeg2000_ceildiv(s->image_offset_x, s->cdx[compno]);                     \
                dst = line + x * pixelsize + compno*!planar;                                      \
                                                                                                  \
                if (codsty->transform == FF_DWT97) {                                              \
                    for (; x < w; x++) {                                                          \
                        int val = lrintf(*datap) + (1 << (cbps - 1));                             \
                        /* DC level shift and clip see ISO 15444-1:2002 G.1.2 */                  \
                        val  = av_clip(val, 0, (1 << cbps) - 1);                                  \
                        *dst = val << (precision - cbps);                                         \
                        datap++;                                                                  \
                        dst += pixelsize;                                                         \
                    }                                                                             \
                } else {                                                                          \
                    for (; x < w; x++) {                                                          \
                        int val = *i_datap + (1 << (cbps - 1));                                   \
                        /* DC level shift and clip see ISO 15444-1:2002 G.1.2 */                  \
                        val  = av_clip(val, 0, (1 << cbps) - 1);                                  \
                        *dst = val << (precision - cbps);                                         \
                        i_datap++;                                                                \
                        dst += pixelsize;                                                         \
                    }                                                                             \
                }                                                                                 \
                line += picture->linesize[plane] / sizeof(PIXEL);                                 \
            }                                                                                     \
        }                                                                                         \
                                                                                                  \
    }

WRITE_FRAME(8, uint8_t)
WRITE_FRAME(16, uint16_t)

#undef WRITE_FRAME

static int jpeg2000_decode_tile(AVCodecContext *avctx, void *td,
                                int jobnr, int threadnr)
{
    const Jpeg2000DecoderContext *s = avctx->priv_data;
    AVFrame *picture = td;
    Jpeg2000Tile *tile = s->tile + jobnr;

    int ret = tile_codeblocks(s, tile);
    if (ret < 0)
        return ret;

    /* inverse MCT transformation */
    if (tile->codsty[0].mct)
        mct_decode(s, tile);

    if (s->precision <= 8) {
        write_frame_8(s, tile, picture, 8);
    } else {
        int precision = picture->format == AV_PIX_FMT_XYZ12 ||
                        picture->format == AV_PIX_FMT_RGB48 ||
                        picture->format == AV_PIX_FMT_RGBA64 ||
                        picture->format == AV_PIX_FMT_GRAY16 ? 16 : s->precision;

        write_frame_16(s, tile, picture, precision);
    }

    return 0;
}

static void jpeg2000_dec_cleanup(Jpeg2000DecoderContext *s)
{
    int tileno, compno;
    for (tileno = 0; tileno < s->numXtiles * s->numYtiles; tileno++) {
        if (s->tile[tileno].comp) {
            for (compno = 0; compno < s->ncomponents; compno++) {
                Jpeg2000Component *comp     = s->tile[tileno].comp   + compno;
                Jpeg2000CodingStyle *codsty = s->tile[tileno].codsty + compno;

                ff_jpeg2000_cleanup(comp, codsty);
            }
            av_freep(&s->tile[tileno].comp);
            av_freep(&s->tile[tileno].packed_headers);
            s->tile[tileno].packed_headers_size = 0;
        }
    }
    av_freep(&s->packed_headers);
    s->packed_headers_size = 0;
    memset(&s->packed_headers_stream, 0, sizeof(s->packed_headers_stream));
    av_freep(&s->tile);
    memset(s->codsty, 0, sizeof(s->codsty));
    memset(s->qntsty, 0, sizeof(s->qntsty));
    memset(s->properties, 0, sizeof(s->properties));
    memset(&s->poc  , 0, sizeof(s->poc));
    s->numXtiles = s->numYtiles = 0;
    s->ncomponents = 0;
}

static int jpeg2000_read_main_headers(Jpeg2000DecoderContext *s)
{
    Jpeg2000CodingStyle *codsty = s->codsty;
    Jpeg2000QuantStyle *qntsty  = s->qntsty;
    Jpeg2000POC         *poc    = &s->poc;
    uint8_t *properties         = s->properties;
    uint8_t in_tile_headers     = 0;

    for (;;) {
        int len, ret = 0;
        uint16_t marker;
        int oldpos;

        if (bytestream2_get_bytes_left(&s->g) < 2) {
            av_log(s->avctx, AV_LOG_ERROR, "Missing EOC\n");
            break;
        }

        marker = bytestream2_get_be16u(&s->g);
        oldpos = bytestream2_tell(&s->g);
        if (marker >= 0xFF30 && marker <= 0xFF3F)
            continue;
        if (marker == JPEG2000_SOD) {
            Jpeg2000Tile *tile;
            Jpeg2000TilePart *tp;

            if (!s->tile) {
                av_log(s->avctx, AV_LOG_ERROR, "Missing SIZ\n");
                return AVERROR_INVALIDDATA;
            }
            if (s->curtileno < 0) {
                av_log(s->avctx, AV_LOG_ERROR, "Missing SOT\n");
                return AVERROR_INVALIDDATA;
            }

            tile = s->tile + s->curtileno;
            tp = tile->tile_part + tile->tp_idx;
            if (tp->tp_end < s->g.buffer) {
                av_log(s->avctx, AV_LOG_ERROR, "Invalid tpend\n");
                return AVERROR_INVALIDDATA;
            }

            if (s->has_ppm) {
                uint32_t tp_header_size = bytestream2_get_be32(&s->packed_headers_stream);
                if (bytestream2_get_bytes_left(&s->packed_headers_stream) < tp_header_size)
                    return AVERROR_INVALIDDATA;
                bytestream2_init(&tp->header_tpg, s->packed_headers_stream.buffer, tp_header_size);
                bytestream2_skip(&s->packed_headers_stream, tp_header_size);
            }
            if (tile->has_ppt && tile->tp_idx == 0) {
                bytestream2_init(&tile->packed_headers_stream, tile->packed_headers, tile->packed_headers_size);
            }

            bytestream2_init(&tp->tpg, s->g.buffer, tp->tp_end - s->g.buffer);
            bytestream2_skip(&s->g, tp->tp_end - s->g.buffer);

            continue;
        }
        if (marker == JPEG2000_EOC)
            break;

        len = bytestream2_get_be16(&s->g);
        if (len < 2 || bytestream2_get_bytes_left(&s->g) < len - 2) {
            if (s->avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
                av_log(s->avctx, AV_LOG_ERROR, "Invalid len %d left=%d\n", len, bytestream2_get_bytes_left(&s->g));
                return AVERROR_INVALIDDATA;
            }
            av_log(s->avctx, AV_LOG_WARNING, "Missing EOC Marker.\n");
            break;
        }

        switch (marker) {
        case JPEG2000_SIZ:
            if (s->ncomponents) {
                av_log(s->avctx, AV_LOG_ERROR, "Duplicate SIZ\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_siz(s);
            if (!s->tile)
                s->numXtiles = s->numYtiles = 0;
            break;
        case JPEG2000_CAP:
            if (!s->ncomponents) {
                av_log(s->avctx, AV_LOG_ERROR, "CAP marker segment shall come after SIZ\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_cap(s, codsty);
            break;
        case JPEG2000_COC:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "COC marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_coc(s, codsty, properties);
            break;
        case JPEG2000_COD:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "COD marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_cod(s, codsty, properties);
            break;
        case JPEG2000_RGN:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "RGN marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_rgn(s, len);
            if ((!s->Ccap15_b12) && s->isHT) {
                av_log(s->avctx, AV_LOG_ERROR, "RGN marker found but the codestream belongs to the RGNFREE set\n");
                return AVERROR_INVALIDDATA;
            }
            break;
        case JPEG2000_QCC:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "QCC marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_qcc(s, len, qntsty, properties);
            break;
        case JPEG2000_QCD:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "QCD marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_qcd(s, len, qntsty, properties);
            break;
        case JPEG2000_POC:
            if (in_tile_headers == 1 && s->isHT && (!s->Ccap15_b11)) {
                av_log(s->avctx, AV_LOG_ERROR,
                    "POC marker found in a tile header but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_poc(s, len, poc);
            break;
        case JPEG2000_SOT:
            if (!in_tile_headers) {
                in_tile_headers = 1;
                if (s->has_ppm) {
                    bytestream2_init(&s->packed_headers_stream, s->packed_headers, s->packed_headers_size);
                }
            }
            if (!(ret = get_sot(s, len))) {
                av_assert1(s->curtileno >= 0);
                codsty = s->tile[s->curtileno].codsty;
                qntsty = s->tile[s->curtileno].qntsty;
                poc    = &s->tile[s->curtileno].poc;
                properties = s->tile[s->curtileno].properties;
            }
            break;
        case JPEG2000_PLM:
            // the PLM marker is ignored
        case JPEG2000_COM:
            // the comment is ignored
            bytestream2_skip(&s->g, len - 2);
            break;
        case JPEG2000_CRG:
            ret = read_crg(s, len);
            break;
        case JPEG2000_TLM:
            // Tile-part lengths
            ret = get_tlm(s, len);
            break;
        case JPEG2000_PLT:
            // Packet length, tile-part header
            ret = get_plt(s, len);
            break;
        case JPEG2000_PPM:
            // Packed headers, main header
            if (in_tile_headers) {
                av_log(s->avctx, AV_LOG_ERROR, "PPM Marker can only be in Main header\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_ppm(s, len);
            break;
        case JPEG2000_PPT:
            // Packed headers, tile-part header
            if (s->has_ppm) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "Cannot have both PPT and PPM marker.\n");
                return AVERROR_INVALIDDATA;
            }
            if ((!s->Ccap15_b11) && s->isHT) {
                av_log(s->avctx, AV_LOG_ERROR, "PPT marker found but the codestream belongs to the HOMOGENEOUS set\n");
                return AVERROR_INVALIDDATA;
            }
            ret = get_ppt(s, len);
            break;
        case JPEG2000_CPF:
            // Corresponding profile marker
            ret = read_cpf(s, len);
            break;
        default:
            av_log(s->avctx, AV_LOG_ERROR,
                   "unsupported marker 0x%.4"PRIX16" at pos 0x%X\n",
                   marker, bytestream2_tell(&s->g) - 4);
            bytestream2_skip(&s->g, len - 2);
            break;
        }
        if (bytestream2_tell(&s->g) - oldpos != len || ret) {
            av_log(s->avctx, AV_LOG_ERROR,
                   "error during processing marker segment %.4"PRIx16"\n",
                   marker);
            return ret ? ret : -1;
        }
    }
    return 0;
}

/* Read bit stream packets --> T2 operation. */
static int jpeg2000_read_bitstream_packets(Jpeg2000DecoderContext *s)
{
    int ret = 0;
    int tileno;

    for (tileno = 0; tileno < s->numXtiles * s->numYtiles; tileno++) {
        Jpeg2000Tile *tile = s->tile + tileno;

        if ((ret = init_tile(s, tileno)) < 0)
            return ret;

        if ((ret = jpeg2000_decode_packets(s, tile)) < 0)
            return ret;
    }

    return 0;
}

static int jp2_find_codestream(Jpeg2000DecoderContext *s)
{
    uint32_t atom_size, atom, atom_end;
    int search_range = 10;

    while (search_range
           &&
           bytestream2_get_bytes_left(&s->g) >= 8) {
        atom_size = bytestream2_get_be32u(&s->g);
        atom      = bytestream2_get_be32u(&s->g);
        if (atom_size == 1) {
            if (bytestream2_get_be32u(&s->g)) {
                avpriv_request_sample(s->avctx, "Huge atom");
                return 0;
            }
            atom_size = bytestream2_get_be32u(&s->g);
            if (atom_size < 16 || (int64_t)bytestream2_tell(&s->g) + atom_size - 16 > INT_MAX)
                return AVERROR_INVALIDDATA;
            atom_end  = bytestream2_tell(&s->g) + atom_size - 16;
        } else {
            if (atom_size <  8 || (int64_t)bytestream2_tell(&s->g) + atom_size -  8 > INT_MAX)
                return AVERROR_INVALIDDATA;
            atom_end  = bytestream2_tell(&s->g) + atom_size -  8;
        }

        if (atom == JP2_CODESTREAM)
            return 1;

        if (bytestream2_get_bytes_left(&s->g) < atom_size || atom_end < atom_size)
            return 0;

        if (atom == JP2_HEADER &&
                   atom_size >= 16) {
            uint32_t atom2_size, atom2, atom2_end;
            do {
                if (bytestream2_get_bytes_left(&s->g) < 8)
                    break;
                atom2_size = bytestream2_get_be32u(&s->g);
                atom2      = bytestream2_get_be32u(&s->g);
                atom2_end  = bytestream2_tell(&s->g) + atom2_size - 8;
                if (atom2_size < 8 || atom2_end > atom_end || atom2_end < atom2_size)
                    break;
                atom2_size -= 8;
                if (atom2 == JP2_CODESTREAM) {
                    return 1;
                } else if (atom2 == MKBETAG('c','o','l','r') && atom2_size >= 7) {
                    int method = bytestream2_get_byteu(&s->g);
                    bytestream2_skipu(&s->g, 2);
                    if (method == 1) {
                        s->colour_space = bytestream2_get_be32u(&s->g);
                    }
                } else if (atom2 == MKBETAG('p','c','l','r') && atom2_size >= 6) {
                    int i, size, colour_count, colour_channels, colour_depth[3];
                    colour_count = bytestream2_get_be16u(&s->g);
                    colour_channels = bytestream2_get_byteu(&s->g);
                    // FIXME: Do not ignore channel_sign
                    colour_depth[0] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[1] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[2] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    size = (colour_depth[0] + 7 >> 3) * colour_count +
                           (colour_depth[1] + 7 >> 3) * colour_count +
                           (colour_depth[2] + 7 >> 3) * colour_count;
                    if (colour_count > AVPALETTE_COUNT ||
                        colour_channels != 3 ||
                        colour_depth[0] > 16 ||
                        colour_depth[1] > 16 ||
                        colour_depth[2] > 16 ||
                        atom2_size < size) {
                        avpriv_request_sample(s->avctx, "Unknown palette");
                        bytestream2_seek(&s->g, atom2_end, SEEK_SET);
                        continue;
                    }
                    s->pal8 = 1;
                    for (i = 0; i < colour_count; i++) {
                        uint32_t r, g, b;
                        if (colour_depth[0] <= 8) {
                            r = bytestream2_get_byteu(&s->g) << 8 - colour_depth[0];
                            r |= r >> colour_depth[0];
                        } else {
                            r = bytestream2_get_be16u(&s->g) >> colour_depth[0] - 8;
                        }
                        if (colour_depth[1] <= 8) {
                            g = bytestream2_get_byteu(&s->g) << 8 - colour_depth[1];
                            g |= g >> colour_depth[1];
                        } else {
                            g = bytestream2_get_be16u(&s->g) >> colour_depth[1] - 8;
                        }
                        if (colour_depth[2] <= 8) {
                            b = bytestream2_get_byteu(&s->g) << 8 - colour_depth[2];
                            b |= b >> colour_depth[2];
                        } else {
                            b = bytestream2_get_be16u(&s->g) >> colour_depth[2] - 8;
                        }
                        s->palette[i] = 0xffu << 24 | r << 16 | g << 8 | b;
                    }
                } else if (atom2 == MKBETAG('c','d','e','f') && atom2_size >= 2) {
                    int n = bytestream2_get_be16u(&s->g);
                    for (; n>0; n--) {
                        int cn   = bytestream2_get_be16(&s->g);
                        int av_unused typ  = bytestream2_get_be16(&s->g);
                        int asoc = bytestream2_get_be16(&s->g);
                        if (cn < 4 && asoc < 4)
                            s->cdef[cn] = asoc;
                    }
                } else if (atom2 == MKBETAG('r','e','s',' ') && atom2_size >= 18) {
                    int64_t vnum, vden, hnum, hden, vexp, hexp;
                    uint32_t resx;
                    bytestream2_skip(&s->g, 4);
                    resx = bytestream2_get_be32u(&s->g);
                    if (resx != MKBETAG('r','e','s','c') && resx != MKBETAG('r','e','s','d')) {
                        bytestream2_seek(&s->g, atom2_end, SEEK_SET);
                        continue;
                    }
                    vnum = bytestream2_get_be16u(&s->g);
                    vden = bytestream2_get_be16u(&s->g);
                    hnum = bytestream2_get_be16u(&s->g);
                    hden = bytestream2_get_be16u(&s->g);
                    vexp = bytestream2_get_byteu(&s->g);
                    hexp = bytestream2_get_byteu(&s->g);
                    if (!vnum || !vden || !hnum || !hden) {
                        bytestream2_seek(&s->g, atom2_end, SEEK_SET);
                        av_log(s->avctx, AV_LOG_WARNING, "RES box invalid\n");
                        continue;
                    }
                    if (vexp > hexp) {
                        vexp -= hexp;
                        hexp = 0;
                    } else {
                        hexp -= vexp;
                        vexp = 0;
                    }
                    if (   INT64_MAX / (hnum * vden) > pow(10, hexp)
                        && INT64_MAX / (vnum * hden) > pow(10, vexp))
                        av_reduce(&s->sar.den, &s->sar.num,
                                  hnum * vden * pow(10, hexp),
                                  vnum * hden * pow(10, vexp),
                                  INT32_MAX);
                }
                bytestream2_seek(&s->g, atom2_end, SEEK_SET);
            } while (atom_end - atom2_end >= 8);
        } else {
            search_range--;
        }
        bytestream2_seek(&s->g, atom_end, SEEK_SET);
    }

    return 0;
}

static av_cold int jpeg2000_decode_init(AVCodecContext *avctx)
{
    Jpeg2000DecoderContext *s = avctx->priv_data;

    if (avctx->lowres)
        av_log(avctx, AV_LOG_WARNING, "lowres is overridden by reduction_factor but set anyway\n");
    if (!s->reduction_factor && avctx->lowres < JPEG2000_MAX_RESLEVELS) {
        s->reduction_factor = avctx->lowres;
    }
    if (avctx->lowres != s->reduction_factor && avctx->lowres)
        return AVERROR(EINVAL);

    ff_jpeg2000dsp_init(&s->dsp);
    ff_jpeg2000_init_tier1_luts();

    return 0;
}

static int jpeg2000_decode_frame(AVCodecContext *avctx, AVFrame *picture,
                                 int *got_frame, AVPacket *avpkt)
{
    Jpeg2000DecoderContext *s = avctx->priv_data;
    int ret;

    s->avctx     = avctx;
    bytestream2_init(&s->g, avpkt->data, avpkt->size);
    s->curtileno = -1;
    memset(s->cdef, -1, sizeof(s->cdef));

    if (bytestream2_get_bytes_left(&s->g) < 2) {
        ret = AVERROR_INVALIDDATA;
        goto end;
    }

    // check if the image is in jp2 format
    if (bytestream2_get_bytes_left(&s->g) >= 12 &&
       (bytestream2_get_be32u(&s->g) == 12) &&
       (bytestream2_get_be32u(&s->g) == JP2_SIG_TYPE) &&
       (bytestream2_get_be32u(&s->g) == JP2_SIG_VALUE)) {
        if (!jp2_find_codestream(s)) {
            av_log(avctx, AV_LOG_ERROR,
                   "Could not find Jpeg2000 codestream atom.\n");
            ret = AVERROR_INVALIDDATA;
            goto end;
        }
    } else {
        bytestream2_seek(&s->g, 0, SEEK_SET);
    }

    while (bytestream2_get_bytes_left(&s->g) >= 3 && bytestream2_peek_be16(&s->g) != JPEG2000_SOC)
        bytestream2_skip(&s->g, 1);

    if (bytestream2_get_be16u(&s->g) != JPEG2000_SOC) {
        av_log(avctx, AV_LOG_ERROR, "SOC marker not present\n");
        ret = AVERROR_INVALIDDATA;
        goto end;
    }
    if (ret = jpeg2000_read_main_headers(s))
        goto end;

    if (s->sar.num && s->sar.den)
        avctx->sample_aspect_ratio = s->sar;
    s->sar.num = s->sar.den = 0;

    if (avctx->skip_frame >= AVDISCARD_ALL) {
        jpeg2000_dec_cleanup(s);
        return avpkt->size;
    }

    /* get picture buffer */
    if ((ret = ff_thread_get_buffer(avctx, picture, 0)) < 0)
        goto end;

    if (ret = jpeg2000_read_bitstream_packets(s))
        goto end;

    for (int x = 0; x < s->ncomponents && s->codsty[x].transform == FF_DWT53;)
        if (++x == s->ncomponents)
            picture->flags |= AV_FRAME_FLAG_LOSSLESS;

    avctx->execute2(avctx, jpeg2000_decode_tile, picture, NULL, s->numXtiles * s->numYtiles);

    jpeg2000_dec_cleanup(s);

    *got_frame = 1;

    if (s->avctx->pix_fmt == AV_PIX_FMT_PAL8)
        memcpy(picture->data[1], s->palette, 256 * sizeof(uint32_t));

    return bytestream2_tell(&s->g);

end:
    jpeg2000_dec_cleanup(s);
    return ret;
}

#define OFFSET(x) offsetof(Jpeg2000DecoderContext, x)
#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {
    { "lowres",  "Lower the decoding resolution by a power of two",
        OFFSET(reduction_factor), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, JPEG2000_MAX_RESLEVELS - 1, VD },
    { NULL },
};

static const AVClass jpeg2000_class = {
    .class_name = "jpeg2000",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

const FFCodec ff_jpeg2000_decoder = {
    .p.name           = "jpeg2000",
    CODEC_LONG_NAME("JPEG 2000"),
    .p.type           = AVMEDIA_TYPE_VIDEO,
    .p.id             = AV_CODEC_ID_JPEG2000,
    .p.capabilities   = AV_CODEC_CAP_SLICE_THREADS | AV_CODEC_CAP_FRAME_THREADS | AV_CODEC_CAP_DR1,
    .priv_data_size   = sizeof(Jpeg2000DecoderContext),
    .init             = jpeg2000_decode_init,
    FF_CODEC_DECODE_CB(jpeg2000_decode_frame),
    .p.priv_class     = &jpeg2000_class,
    .p.max_lowres     = 5,
    .p.profiles       = NULL_IF_CONFIG_SMALL(ff_jpeg2000_profiles),
    .caps_internal    = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,
};
