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  1. /*
  2.  * MJPEG A dump header bitstream filter
  3.  * Copyright (c) 2006 Baptiste Coudurier
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * MJPEG A dump header bitstream filter
  25.  * modifies bitstream to be decoded by quicktime
  26.  */
  27.  
  28. #include "avcodec.h"
  29. #include "bytestream.h"
  30. #include "mjpeg.h"
  31.  
  32.  
  33. static int mjpega_dump_header(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
  34.                               uint8_t **poutbuf, int *poutbuf_size,
  35.                               const uint8_t *buf, int buf_size, int keyframe)
  36. {
  37.     uint8_t *poutbufp;
  38.     unsigned dqt = 0, dht = 0, sof0 = 0;
  39.     int i;
  40.  
  41.     if (avctx->codec_id != AV_CODEC_ID_MJPEG) {
  42.         av_log(avctx, AV_LOG_ERROR, "mjpega bitstream filter only applies to mjpeg codec\n");
  43.         return 0;
  44.     }
  45.  
  46.     *poutbuf_size = 0;
  47.     *poutbuf = av_malloc(buf_size + 44 + FF_INPUT_BUFFER_PADDING_SIZE);
  48.     poutbufp = *poutbuf;
  49.     bytestream_put_byte(&poutbufp, 0xff);
  50.     bytestream_put_byte(&poutbufp, SOI);
  51.     bytestream_put_byte(&poutbufp, 0xff);
  52.     bytestream_put_byte(&poutbufp, APP1);
  53.     bytestream_put_be16(&poutbufp, 42); /* size */
  54.     bytestream_put_be32(&poutbufp, 0);
  55.     bytestream_put_buffer(&poutbufp, "mjpg", 4);
  56.     bytestream_put_be32(&poutbufp, buf_size + 44); /* field size */
  57.     bytestream_put_be32(&poutbufp, buf_size + 44); /* pad field size */
  58.     bytestream_put_be32(&poutbufp, 0);             /* next ptr */
  59.  
  60.     for (i = 0; i < buf_size - 1; i++) {
  61.         if (buf[i] == 0xff) {
  62.             switch (buf[i + 1]) {
  63.             case DQT:  dqt  = i + 46; break;
  64.             case DHT:  dht  = i + 46; break;
  65.             case SOF0: sof0 = i + 46; break;
  66.             case SOS:
  67.                 bytestream_put_be32(&poutbufp, dqt); /* quant off */
  68.                 bytestream_put_be32(&poutbufp, dht); /* huff off */
  69.                 bytestream_put_be32(&poutbufp, sof0); /* image off */
  70.                 bytestream_put_be32(&poutbufp, i + 46); /* scan off */
  71.                 bytestream_put_be32(&poutbufp, i + 46 + AV_RB16(buf + i + 2)); /* data off */
  72.                 bytestream_put_buffer(&poutbufp, buf + 2, buf_size - 2); /* skip already written SOI */
  73.                 *poutbuf_size = poutbufp - *poutbuf;
  74.                 return 1;
  75.             case APP1:
  76.                 if (i + 8 < buf_size && AV_RL32(buf + i + 8) == AV_RL32("mjpg")) {
  77.                     av_log(avctx, AV_LOG_ERROR, "bitstream already formatted\n");
  78.                     memcpy(*poutbuf, buf, buf_size);
  79.                     *poutbuf_size = buf_size;
  80.                     return 1;
  81.                 }
  82.             }
  83.         }
  84.     }
  85.     av_freep(poutbuf);
  86.     av_log(avctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
  87.     return 0;
  88. }
  89.  
  90. AVBitStreamFilter ff_mjpega_dump_header_bsf = {
  91.     .name   = "mjpegadump",
  92.     .filter = mjpega_dump_header,
  93. };
  94.