PeerStreamer

/*

 * Copyright (C) 2008  Ramiro Polla

 *

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavcodec/bytestream.h"

#include "avformat.h"

#define HEADER_SIZE         24

/*

 * Header structure:

 *  uint16_t    ss;     // struct size

 *  uint16_t    width;  // frame width

 *  uint16_t    height; // frame height

 *  uint16_t    ff;     // keyframe + some other info(???)

 *  uint32_t    size;   // size of data

 *  uint32_t    fourcc; // ML20

 *  uint32_t    u3;     // ?

 *  uint32_t    ts;     // time

 */

static int msnwc_tcp_probe(AVProbeData *p)

{

    int i;

    for(i = 0 ; i + HEADER_SIZE <= p->buf_size ; i++) {

        uint16_t width, height;

        uint32_t fourcc;

        const uint8_t *bytestream = p->buf+i;

        if(bytestream_get_le16(&bytestream) != HEADER_SIZE)

            continue;

        width  = bytestream_get_le16(&bytestream);

        height = bytestream_get_le16(&bytestream);

        if(!(width==320 && height==240) && !(width==160 && height==120))

            continue;

        bytestream += 2; // keyframe

        bytestream += 4; // size

        fourcc = bytestream_get_le32(&bytestream);

        if(fourcc != MKTAG('M', 'L', '2', '0'))

            continue;

        if(i) {

            if(i < 14)  /* starts with SwitchBoard connection info */

                return AVPROBE_SCORE_MAX / 2;

            else        /* starts in the middle of stream */

                return AVPROBE_SCORE_MAX / 3;

        } else {

            return AVPROBE_SCORE_MAX;

        }

    }

    return -1;

}

static int msnwc_tcp_read_header(AVFormatContext *ctx, AVFormatParameters *ap)

{

    AVIOContext *pb = ctx->pb;

    AVCodecContext *codec;

    AVStream *st;

    st = av_new_stream(ctx, 0);

    if(!st)

        return AVERROR(ENOMEM);

    codec = st->codec;

    codec->codec_type = AVMEDIA_TYPE_VIDEO;

    codec->codec_id = CODEC_ID_MIMIC;

    codec->codec_tag = MKTAG('M', 'L', '2', '0');

    av_set_pts_info(st, 32, 1, 1000);

    /* Some files start with "connected\r\n\r\n".

     * So skip until we find the first byte of struct size */

    while(avio_r8(pb) != HEADER_SIZE && !pb->eof_reached);

    if(pb->eof_reached) {

        av_log(ctx, AV_LOG_ERROR, "Could not find valid start.");

        return -1;

    }

    return 0;

}

static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)

{

    AVIOContext *pb = ctx->pb;

    uint16_t keyframe;

    uint32_t size, timestamp;

    avio_skip(pb, 1); /* one byte has been read ahead */

    avio_skip(pb, 2);

    avio_skip(pb, 2);

    keyframe = avio_rl16(pb);

    size = avio_rl32(pb);

    avio_skip(pb, 4);

    avio_skip(pb, 4);

    timestamp = avio_rl32(pb);

    if(!size || av_get_packet(pb, pkt, size) != size)

        return -1;

    avio_skip(pb, 1); /* Read ahead one byte of struct size like read_header */

    pkt->pts = timestamp;

    pkt->dts = timestamp;

    pkt->stream_index = 0;

    /* Some aMsn generated videos (or was it Mercury Messenger?) don't set

     * this bit and rely on the codec to get keyframe information */

    if(keyframe&1)

        pkt->flags |= AV_PKT_FLAG_KEY;

    return HEADER_SIZE + size;

}

AVInputFormat ff_msnwc_tcp_demuxer = {

    "msnwctcp",

    NULL_IF_CONFIG_SMALL("MSN TCP Webcam stream"),

    0,

    msnwc_tcp_probe,

    msnwc_tcp_read_header,

    msnwc_tcp_read_packet,

};