FFmpeg: libavformat/msnwc_tcp.c Source File

FFmpeg
msnwc_tcp.c
Go to the documentation of this file.
1 /*
2  * Copyright (C) 2008 Ramiro Polla
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavcodec/bytestream.h"
22 #include "avformat.h"
23 #include "internal.h"
24 
25  #define HEADER_SIZE 24
26 
27 /*
28  * Header structure:
29  * uint16_t ss; // struct size
30  * uint16_t width; // frame width
31  * uint16_t height; // frame height
32  * uint16_t ff; // keyframe + some other info(???)
33  * uint32_t size; // size of data
34  * uint32_t fourcc; // ML20
35  * uint32_t u3; // ?
36  * uint32_t ts; // time
37  */
38 
39  static int msnwc_tcp_probe(const AVProbeData *p)
40 {
41  int i;
42 
43  for (i = 0; i + HEADER_SIZE <= p->buf_size; i++) {
44  uint16_t width, height;
45  uint32_t fourcc;
46  const uint8_t *bytestream = p->buf + i;
47 
48  if (bytestream_get_le16(&bytestream) != HEADER_SIZE)
49  continue;
50  width = bytestream_get_le16(&bytestream);
51  height = bytestream_get_le16(&bytestream);
52  if (!(width == 320 &&
53  height == 240) && !(width == 160 && height == 120))
54  continue;
55  bytestream += 2; // keyframe
56  bytestream += 4; // size
57  fourcc = bytestream_get_le32(&bytestream);
58  if (fourcc != MKTAG('M', 'L', '2', '0'))
59  continue;
60 
61  if (i) {
62  if (i < 14) /* starts with SwitchBoard connection info */
63  return AVPROBE_SCORE_MAX / 2;
64  else /* starts in the middle of stream */
65  return AVPROBE_SCORE_MAX / 3;
66  } else {
67  return AVPROBE_SCORE_MAX;
68  }
69  }
70 
71  return 0;
72 }
73 
74  static int msnwc_tcp_read_header(AVFormatContext *ctx)
75 {
76  AVIOContext *pb = ctx->pb;
77  AVCodecParameters *par;
78  AVStream *st;
79 
80  st = avformat_new_stream(ctx, NULL);
81  if (!st)
82  return AVERROR(ENOMEM);
83 
84  par = st->codecpar;
85  par->codec_type = AVMEDIA_TYPE_VIDEO;
86  par->codec_id = AV_CODEC_ID_MIMIC;
87  par->codec_tag = MKTAG('M', 'L', '2', '0');
88 
89  avpriv_set_pts_info(st, 32, 1, 1000);
90 
91  /* Some files start with "connected\r\n\r\n".
92  * So skip until we find the first byte of struct size */
93  while(avio_r8(pb) != HEADER_SIZE && !avio_feof(pb)) ;
94 
95  if(avio_feof(pb)) {
96  av_log(ctx, AV_LOG_ERROR, "Could not find valid start.\n");
97  return AVERROR_INVALIDDATA;
98  }
99 
100  return 0;
101 }
102 
103  static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
104 {
105  AVIOContext *pb = ctx->pb;
106  uint16_t keyframe;
107  uint32_t size, timestamp;
108  int ret;
109 
110  avio_skip(pb, 1); /* one byte has been read ahead */
111  avio_skip(pb, 2);
112  avio_skip(pb, 2);
113  keyframe = avio_rl16(pb);
114  size = avio_rl32(pb);
115  avio_skip(pb, 4);
116  avio_skip(pb, 4);
117  timestamp = avio_rl32(pb);
118 
119  if (!size)
120  return AVERROR_INVALIDDATA;
121 
122  if ((ret = av_get_packet(pb, pkt, size)) < 0)
123  return ret;
124 
125  avio_skip(pb, 1); /* Read ahead one byte of struct size like read_header */
126 
127  pkt->pts = timestamp;
128  pkt->dts = timestamp;
129  pkt->stream_index = 0;
130 
131  /* Some aMsn generated videos (or was it Mercury Messenger?) don't set
132  * this bit and rely on the codec to get keyframe information */
133  if (keyframe & 1)
134  pkt->flags |= AV_PKT_FLAG_KEY;
135 
136  return HEADER_SIZE + size;
137 }
138 
139  const AVInputFormat ff_msnwc_tcp_demuxer = {
140  .name = "msnwctcp",
141  .long_name = NULL_IF_CONFIG_SMALL("MSN TCP Webcam stream"),
142  .read_probe = msnwc_tcp_probe,
143  .read_header = msnwc_tcp_read_header,
144  .read_packet = msnwc_tcp_read_packet,
145 };
AVERROR
Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: options.c:243
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:58
AVCodecParameters
This struct describes the properties of an encoded stream.
Definition: codec_par.h:54
msnwc_tcp_read_packet
static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition: msnwc_tcp.c:103
HEADER_SIZE
#define HEADER_SIZE
Definition: msnwc_tcp.c:25
AVCodecParameters::codec_tag
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:66
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:454
AV_PKT_FLAG_KEY
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:429
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:463
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:771
AV_CODEC_ID_MIMIC
@ AV_CODEC_ID_MIMIC
Definition: codec_id.h:165
avio_rl16
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:735
ff_msnwc_tcp_demuxer
const AVInputFormat ff_msnwc_tcp_demuxer
Definition: msnwc_tcp.c:139
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
AVInputFormat
Definition: avformat.h:546
width
#define width
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:551
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AVFormatContext
Format I/O context.
Definition: avformat.h:1104
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:861
NULL
#define NULL
Definition: coverity.c:32
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1146
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:751
AVIOContext
Bytestream IO Context.
Definition: avio.h:166
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:115
size
int size
Definition: twinvq_data.h:10344
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:373
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:624
height
#define height
AVPacket::flags
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:380
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:367
av_get_packet
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:102
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:838
avformat.h
msnwc_tcp_read_header
static int msnwc_tcp_read_header(AVFormatContext *ctx)
Definition: msnwc_tcp.c:74
AVPacket::stream_index
int stream_index
Definition: packet.h:376
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:339
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:62
AVPacket
This structure stores compressed data.
Definition: packet.h:351
bytestream.h
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
MKTAG
#define MKTAG(a, b, c, d)
Definition: macros.h:55
fourcc
uint32_t fourcc
Definition: vaapi_decode.c:241
msnwc_tcp_probe
static int msnwc_tcp_probe(const AVProbeData *p)
Definition: msnwc_tcp.c:39
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:367
Generated on Tue Feb 28 2023 21:34:07 for FFmpeg by   doxygen 1.8.17

AltStyle によって変換されたページ (->オリジナル) /