ffmpeg/libavformat/msnwc_tcp.c

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/*
* Copyright (C) 2008 Ramiro Polla
*
* 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 "libavcodec/bytestream.h"
#include "avformat.h"
#include "internal.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 0;
}
static int msnwc_tcp_read_header(AVFormatContext *ctx)
{
AVIOContext *pb = ctx->pb;
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 20:42:52 +02:00
AVCodecParameters *par;
AVStream *st;
st = avformat_new_stream(ctx, NULL);
if (!st)
return AVERROR(ENOMEM);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 20:42:52 +02:00
par = st->codecpar;
par->codec_type = AVMEDIA_TYPE_VIDEO;
par->codec_id = AV_CODEC_ID_MIMIC;
par->codec_tag = MKTAG('M', 'L', '2', '0');
avpriv_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 && !avio_feof(pb)) ;
if(avio_feof(pb)) {
av_log(ctx, AV_LOG_ERROR, "Could not find valid start.\n");
return AVERROR_INVALIDDATA;
}
return 0;
}
static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
{
AVIOContext *pb = ctx->pb;
uint16_t keyframe;
uint32_t size, timestamp;
int ret;
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)
return AVERROR_INVALIDDATA;
if ((ret = av_get_packet(pb, pkt, size)) < 0)
return ret;
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 = {
.name = "msnwctcp",
.long_name = NULL_IF_CONFIG_SMALL("MSN TCP Webcam stream"),
.read_probe = msnwc_tcp_probe,
.read_header = msnwc_tcp_read_header,
.read_packet = msnwc_tcp_read_packet,
};