FFmpeg  4.4.6
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(const 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 
48 {
50 
51  if (!st)
52  return AVERROR(ENOMEM);
53 
57 
58  avpriv_set_pts_info(st, 64, 1, 100);
59 
60  return 0;
61 }
62 
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  return AVERROR(EIO);
87  }
88 
89  pkt->stream_index = 0;
90  return size;
91 }
92 
94  .name = "nc",
95  .long_name = NULL_IF_CONFIG_SMALL("NC camera feed"),
96  .read_probe = nc_probe,
97  .read_header = nc_read_header,
98  .read_packet = nc_read_packet,
99  .extensions = "v",
100 };
Main libavformat public API header.
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
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
@ AVSTREAM_PARSE_FULL
full parsing and repack
Definition: avformat.h:794
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:364
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:734
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:337
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:624
#define AV_RL16
Definition: intreadwrite.h:42
#define AV_RB32
Definition: intreadwrite.h:130
#define s(width, name)
Definition: cbs_vp9.c:257
static struct @321 state
#define NULL
Definition: coverity.c:32
@ AV_CODEC_ID_MPEG4
Definition: codec_id.h:61
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4509
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:215
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
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:4945
common internal API header
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
static int nc_read_header(AVFormatContext *s)
Definition: ncdec.c:47
static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: ncdec.c:63
#define NC_VIDEO_FLAG
Definition: ncdec.c:27
static int nc_probe(const AVProbeData *probe_packet)
Definition: ncdec.c:29
AVInputFormat ff_nc_demuxer
Definition: ncdec.c:93
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
Format I/O context.
Definition: avformat.h:1232
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:645
This structure stores compressed data.
Definition: packet.h:346
int stream_index
Definition: packet.h:371
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:444
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
Stream structure.
Definition: avformat.h:873
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1038
enum AVStreamParseType need_parsing
Definition: avformat.h:1081
#define av_log(a,...)
AVPacket * pkt
Definition: movenc.c:59
int size