FFmpeg/libavformat/ingenientdec.c

/*
 * RAW Ingenient MJPEG demuxer
 * Copyright (c) 2005 Alex Beregszaszi
 *
 * 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"
#include "libavutil/intreadwrite.h"

// http://multimedia.cx/ingenient.txt
static int ingenient_probe(const AVProbeData *p)
{
    if (   AV_RN32(p->buf) != AV_RN32("MJPG")
        || p->buf_size < 50
        || AV_RB16(p->buf + 48) != 0xffd8)
        return 0;
    return AVPROBE_SCORE_MAX * 3 / 4;
}

static int ingenient_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    int ret, size, w, h, unk1, unk2;

    if (avio_rl32(s->pb) != MKTAG('M', 'J', 'P', 'G'))
        return AVERROR(EIO); // FIXME

    size = avio_rl32(s->pb);

    w = avio_rl16(s->pb);
    h = avio_rl16(s->pb);

    avio_skip(s->pb, 8); // zero + size (padded?)
    avio_skip(s->pb, 2);
    unk1 = avio_rl16(s->pb);
    unk2 = avio_rl16(s->pb);
    avio_skip(s->pb, 22); // ASCII timestamp

    av_log(s, AV_LOG_DEBUG, "Ingenient packet: size=%d, width=%d, height=%d, unk1=%d unk2=%d\n",
        size, w, h, unk1, unk2);

    ret = av_get_packet(s->pb, pkt, size);
    if (ret < 0)
        return ret;
    pkt->stream_index = 0;
    return ret;
}

FF_RAWVIDEO_DEMUXER_CLASS(ingenient)

AVInputFormat ff_ingenient_demuxer = {
    .name           = "ingenient",
    .long_name      = NULL_IF_CONFIG_SMALL("raw Ingenient MJPEG"),
    .priv_data_size = sizeof(FFRawVideoDemuxerContext),
    .read_probe     = ingenient_probe,
    .read_header    = ff_raw_video_read_header,
    .read_packet    = ingenient_read_packet,
    .flags          = AVFMT_GENERIC_INDEX,
    .extensions     = "cgi", // FIXME
    .raw_codec_id   = AV_CODEC_ID_MJPEG,
    .priv_class     = &ingenient_demuxer_class,
};