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mjpega_dump_header_bsf.c
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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  if (!*poutbuf)
49  return AVERROR(ENOMEM);
50  poutbufp = *poutbuf;
51  bytestream_put_byte(&poutbufp, 0xff);
52  bytestream_put_byte(&poutbufp, SOI);
53  bytestream_put_byte(&poutbufp, 0xff);
54  bytestream_put_byte(&poutbufp, APP1);
55  bytestream_put_be16(&poutbufp, 42); /* size */
56  bytestream_put_be32(&poutbufp, 0);
57  bytestream_put_buffer(&poutbufp, "mjpg", 4);
58  bytestream_put_be32(&poutbufp, buf_size + 44); /* field size */
59  bytestream_put_be32(&poutbufp, buf_size + 44); /* pad field size */
60  bytestream_put_be32(&poutbufp, 0); /* next ptr */
61 
62  for (i = 0; i < buf_size - 1; i++) {
63  if (buf[i] == 0xff) {
64  switch (buf[i + 1]) {
65  case DQT: dqt = i + 46; break;
66  case DHT: dht = i + 46; break;
67  case SOF0: sof0 = i + 46; break;
68  case SOS:
69  bytestream_put_be32(&poutbufp, dqt); /* quant off */
70  bytestream_put_be32(&poutbufp, dht); /* huff off */
71  bytestream_put_be32(&poutbufp, sof0); /* image off */
72  bytestream_put_be32(&poutbufp, i + 46); /* scan off */
73  bytestream_put_be32(&poutbufp, i + 46 + AV_RB16(buf + i + 2)); /* data off */
74  bytestream_put_buffer(&poutbufp, buf + 2, buf_size - 2); /* skip already written SOI */
75  *poutbuf_size = poutbufp - *poutbuf;
76  return 1;
77  case APP1:
78  if (i + 8 < buf_size && AV_RL32(buf + i + 8) == AV_RL32("mjpg")) {
79  av_log(avctx, AV_LOG_ERROR, "bitstream already formatted\n");
80  memcpy(*poutbuf, buf, buf_size);
81  *poutbuf_size = buf_size;
82  return 1;
83  }
84  }
85  }
86  }
87  av_freep(poutbuf);
88  av_log(avctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
89  return 0;
90 }
91 
93  .name = "mjpegadump",
94  .filter = mjpega_dump_header,
95 };