FFmpeg: libavformat/ncdec.c Source File

FFmpeg
ncdec.c
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1 /*
2  * NC camera feed demuxer
3  * Copyright (c) 2009 Nicolas Martin (martinic at iro dot umontreal dot ca)
4  * Edouard Auvinet
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "libavutil/intreadwrite.h"
24 #include "avformat.h"
25 #include "internal.h"
26 
27  #define NC_VIDEO_FLAG 0x1A5
28 
29  static int nc_probe(AVProbeData *probe_packet)
30 {
31  int size;
32 
33  if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
34  return 0;
35 
36  size = AV_RL16(probe_packet->buf + 5);
37 
38  if (size + 20 > probe_packet->buf_size)
39  return AVPROBE_SCORE_MAX/4;
40 
41  if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
42  return AVPROBE_SCORE_MAX;
43 
44  return 0;
45 }
46 
47  static int nc_read_header(AVFormatContext *s)
48 {
49  AVStream *st = avformat_new_stream(s, NULL);
50 
51  if (!st)
52  return AVERROR(ENOMEM);
53 
54  st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
55  st->codecpar->codec_id = AV_CODEC_ID_MPEG4;
56  st->need_parsing = AVSTREAM_PARSE_FULL;
57 
58  avpriv_set_pts_info(st, 64, 1, 100);
59 
60  return 0;
61 }
62 
63  static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
64 {
65  int size;
66  int ret;
67 
68  uint32_t state=-1;
69  while (state != NC_VIDEO_FLAG) {
70  if (avio_feof(s->pb))
71  return AVERROR(EIO);
72  state = (state<<8) + avio_r8(s->pb);
73  }
74 
75  avio_r8(s->pb);
76  size = avio_rl16(s->pb);
77  avio_skip(s->pb, 9);
78 
79  if (size == 0) {
80  av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
81  return AVERROR(EAGAIN);
82  }
83 
84  ret = av_get_packet(s->pb, pkt, size);
85  if (ret != size) {
86  if (ret > 0) av_packet_unref(pkt);
87  return AVERROR(EIO);
88  }
89 
90  pkt->stream_index = 0;
91  return size;
92 }
93 
94  AVInputFormat ff_nc_demuxer = {
95  .name = "nc",
96  .long_name = NULL_IF_CONFIG_SMALL("NC camera feed"),
97  .read_probe = nc_probe,
98  .read_header = nc_read_header,
99  .read_packet = nc_read_packet,
100  .extensions = "v",
101 };
NULL
#define NULL
Definition: coverity.c:32
s
const char * s
Definition: avisynth_c.h:768
nc_read_packet
static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: ncdec.c:63
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4820
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3884
NC_VIDEO_FLAG
#define NC_VIDEO_FLAG
Definition: ncdec.c:27
AV_CODEC_ID_MPEG4
Definition: avcodec.h:230
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:331
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
AV_RL16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:87
AVFormatContext
Format I/O context.
Definition: avformat.h:1342
AVStream::need_parsing
enum AVStreamParseType need_parsing
Definition: avformat.h:1091
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4450
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:87
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:310
size
ptrdiff_t size
Definition: opengl_enc.c:101
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
nc_probe
static int nc_probe(AVProbeData *probe_packet)
Definition: ncdec.c:29
AVERROR
#define AVERROR(e)
Definition: error.h:43
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:186
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3880
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:639
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:451
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:450
state
static struct @271 state
AVStream
Stream structure.
Definition: avformat.h:873
ff_nc_demuxer
AVInputFormat ff_nc_demuxer
Definition: ncdec.c:94
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1384
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:592
nc_read_header
static int nc_read_header(AVFormatContext *s)
Definition: ncdec.c:47
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:448
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:460
AVSTREAM_PARSE_FULL
full parsing and repack
Definition: avformat.h:793
avio_rl16
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:754
avformat.h
Main libavformat public API header.
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:647
AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1020
avio_feof
int avio_feof(AVIOContext *s)
feof() equivalent for AVIOContext.
Definition: aviobuf.c:358
AVPacket::stream_index
int stream_index
Definition: avcodec.h:1432
AVPacket
This structure stores compressed data.
Definition: avcodec.h:1407
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