libavcodec/mjpega_dump_header_bsf.c

   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 mjpega_dump_header_bsf.c
  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     int i;
  39
  40     if (avctx->codec_id != CODEC_ID_MJPEG) {
  41         av_log(avctx, AV_LOG_ERROR, "mjpega bitstream filter only applies to mjpeg codec\n");
  42         return 0;
  43     }
  44
  45     *poutbuf_size = 0;
  46     *poutbuf = av_malloc(buf_size + 44 + FF_INPUT_BUFFER_PADDING_SIZE);
  47     poutbufp = *poutbuf;
  48     bytestream_put_byte(&poutbufp, 0xff);
  49     bytestream_put_byte(&poutbufp, SOI);
  50     bytestream_put_byte(&poutbufp, 0xff);
  51     bytestream_put_byte(&poutbufp, APP1);
  52     bytestream_put_be16(&poutbufp, 42); /* size */
  53     bytestream_put_be32(&poutbufp, 0);
  54     bytestream_put_buffer(&poutbufp, "mjpg", 4);
  55     bytestream_put_be32(&poutbufp, buf_size + 44); /* field size */
  56     bytestream_put_be32(&poutbufp, buf_size + 44); /* pad field size */
  57     bytestream_put_be32(&poutbufp, 0);             /* next ptr */
  58
  59     for (i = 0; i < buf_size - 1; i++) {
  60         if (buf[i] == 0xff) {
  61             switch (buf[i + 1]) {
  62             case DQT:  /* quant off */
  63             case DHT:  /* huff  off */
  64             case SOF0: /* image off */
  65                 bytestream_put_be32(&poutbufp, i + 46);
  66                 break;
  67             case SOS:
  68                 bytestream_put_be32(&poutbufp, i + 46); /* scan off */
  69                 bytestream_put_be32(&poutbufp, i + 46 + AV_RB16(buf + i + 2)); /* data off */
  70                 bytestream_put_buffer(&poutbufp, buf + 2, buf_size - 2); /* skip already written SOI */
  71                 *poutbuf_size = poutbufp - *poutbuf;
  72                 return 1;
  73             case APP1:
  74                 if (i + 8 < buf_size && AV_RL32(buf + i + 8) == ff_get_fourcc("mjpg")) {
  75                     av_log(avctx, AV_LOG_ERROR, "bitstream already formatted\n");
  76                     memcpy(*poutbuf, buf, buf_size);
  77                     *poutbuf_size = buf_size;
  78                     return 1;
  79                 }
  80             }
  81         }
  82     }
  83     av_freep(poutbuf);
  84     av_log(avctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
  85     return 0;
  86 }
  87
  88 AVBitStreamFilter mjpega_dump_header_bsf = {
  89     "mjpegadump",
  90     0,
  91     mjpega_dump_header,
  92 };