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
33static 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 != 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
90AVBitStreamFilter mjpega_dump_header_bsf = {
91    "mjpegadump",
92    0,
93    mjpega_dump_header,
94};
95