FFmpeg/libavformat/mpegvideodec.c

/*
 * RAW MPEG video demuxer
 * Copyright (c) 2002-2003 Fabrice Bellard
 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
 *
 * 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
 */

#include "avformat.h"
#include "rawdec.h"

#define SEQ_START_CODE          0x000001b3
#define GOP_START_CODE          0x000001b8
#define PICTURE_START_CODE      0x00000100
#define SLICE_START_CODE        0x00000101
#define PACK_START_CODE         0x000001ba
#define VIDEO_ID                0x000001e0
#define AUDIO_ID                0x000001c0

static int mpegvideo_probe(AVProbeData *p)
{
    uint32_t code= -1;
    int pic=0, seq=0, slice=0, pspack=0, pes=0;
    int i;

    for(i=0; i<p->buf_size; i++){
        code = (code<<8) + p->buf[i];
        if ((code & 0xffffff00) == 0x100) {
            switch(code){
            case     SEQ_START_CODE:   seq++; break;
            case PICTURE_START_CODE:   pic++; break;
            case   SLICE_START_CODE: slice++; break;
            case    PACK_START_CODE: pspack++; break;
            }
            if     ((code & 0x1f0) == VIDEO_ID)   pes++;
            else if((code & 0x1e0) == AUDIO_ID)   pes++;
        }
    }
    if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !pes)
        return pic>1 ? AVPROBE_SCORE_MAX/2+1 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
    return 0;
}

AVInputFormat ff_mpegvideo_demuxer = {
    "mpegvideo",
    NULL_IF_CONFIG_SMALL("raw MPEG video"),
    0,
    mpegvideo_probe,
    ff_raw_video_read_header,
    ff_raw_read_partial_packet,
    .flags= AVFMT_GENERIC_INDEX,
    .value = CODEC_ID_MPEG1VIDEO,
};