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/*

 * Apple MJPEG-B decoder

 * Copyright (c) 2002 Alex Beregszaszi

 *

 * 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

 * Apple MJPEG-B decoder.

 */

#include "avcodec.h"

#include "mjpeg.h"

#include "mjpegdec.h"

static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){

    uint32_t offs= get_bits_long(gb, 32);

    if(offs >= size){

        av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);

        return 0;

    }

    return offs;

}

static int mjpegb_decode_frame(AVCodecContext *avctx,

                              void *data, int *got_frame,

                              AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    MJpegDecodeContext *s = avctx->priv_data;

    const uint8_t *buf_end, *buf_ptr;

    GetBitContext hgb; /* for the header */

    uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;

    uint32_t field_size, sod_offs;

    int ret;

    buf_ptr = buf;

    buf_end = buf + buf_size;

    s->got_picture = 0;

read_header:

    /* reset on every SOI */

    s->restart_interval = 0;

    s->restart_count = 0;

    s->mjpb_skiptosod = 0;

    if (buf_end - buf_ptr >= 1 << 28)

        return AVERROR_INVALIDDATA;

    init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);

    skip_bits(&hgb, 32); /* reserved zeros */

    if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))

    {

        av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");

        return AVERROR_INVALIDDATA;

    }

    field_size = get_bits_long(&hgb, 32); /* field size */

    av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);

    skip_bits(&hgb, 32); /* padded field size */

    second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);

    dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);

    if (dqt_offs)

    {

        init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);

        s->start_code = DQT;

        if (ff_mjpeg_decode_dqt(s) < 0 &&

            (avctx->err_recognition & AV_EF_EXPLODE))

          return AVERROR_INVALIDDATA;

    }

    dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);

    if (dht_offs)

    {

        init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);

        s->start_code = DHT;

        ff_mjpeg_decode_dht(s);

    }

    sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);

    if (sof_offs)

    {

        init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);

        s->start_code = SOF0;

        if (ff_mjpeg_decode_sof(s) < 0)

            return -1;

    }

    sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);

    sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");

    av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);

    if (sos_offs)

    {

        init_get_bits(&s->gb, buf_ptr + sos_offs,

                      8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));

        s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));

        s->start_code = SOS;

        if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&

            (avctx->err_recognition & AV_EF_EXPLODE))

          return AVERROR_INVALIDDATA;

    }

    if (s->interlaced) {

        s->bottom_field ^= 1;

        /* if not bottom field, do not output image yet */

        if (s->bottom_field != s->interlace_polarity && second_field_offs)

        {

            buf_ptr = buf + second_field_offs;

            goto read_header;

            }

    }

    //XXX FIXME factorize, this looks very similar to the EOI code

    if(!s->got_picture) {

        av_log(avctx, AV_LOG_WARNING, "no picture\n");

        return buf_size;

    }

    if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)

        return ret;

    *got_frame = 1;

    if (!s->lossless && avctx->debug & FF_DEBUG_QP) {

        av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",

               FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));

    }

    return buf_size;

}

AVCodec ff_mjpegb_decoder = {

    .name           = "mjpegb",

    .long_name      = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_MJPEGB,

    .priv_data_size = sizeof(MJpegDecodeContext),

    .init           = ff_mjpeg_decode_init,

    .close          = ff_mjpeg_decode_end,

    .decode         = mjpegb_decode_frame,

    .capabilities   = CODEC_CAP_DR1,

    .max_lowres     = 3,

};