FFmpeg
avr.c
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1 /*
2  * AVR demuxer
3  * Copyright (c) 2012 Paul B Mahol
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/intreadwrite.h"
23 #include "avformat.h"
24 #include "internal.h"
25 #include "pcm.h"
26 
27 static int avr_probe(const AVProbeData *p)
28 {
29  if (AV_RL32(p->buf) != MKTAG('2', 'B', 'I', 'T'))
30  return 0;
31 
32  if (!AV_RB16(p->buf+12) || AV_RB16(p->buf+12) > 256) // channels
33  return AVPROBE_SCORE_EXTENSION/2;
34  if (AV_RB16(p->buf+14) > 256) // bps
35  return AVPROBE_SCORE_EXTENSION/2;
36 
38 }
39 
41 {
42  uint16_t chan, sign, bps;
43  AVStream *st;
44 
45  st = avformat_new_stream(s, NULL);
46  if (!st)
47  return AVERROR(ENOMEM);
48 
50 
51  avio_skip(s->pb, 4); // magic
52  avio_skip(s->pb, 8); // sample_name
53 
54  chan = avio_rb16(s->pb);
55  if (!chan) {
56  st->codecpar->channels = 1;
57  } else if (chan == 0xFFFFu) {
58  st->codecpar->channels = 2;
59  } else {
60  avpriv_request_sample(s, "chan %d", chan);
61  return AVERROR_PATCHWELCOME;
62  }
63 
65 
66  sign = avio_rb16(s->pb);
67 
68  avio_skip(s->pb, 2); // loop
69  avio_skip(s->pb, 2); // midi
70  avio_skip(s->pb, 1); // replay speed
71 
72  st->codecpar->sample_rate = avio_rb24(s->pb);
73  avio_skip(s->pb, 4 * 3);
74  avio_skip(s->pb, 2 * 3);
75  avio_skip(s->pb, 20);
76  avio_skip(s->pb, 64);
77 
78  st->codecpar->codec_id = ff_get_pcm_codec_id(bps, 0, 1, sign);
79  if (st->codecpar->codec_id == AV_CODEC_ID_NONE) {
80  avpriv_request_sample(s, "Bps %d and sign %d", bps, sign);
81  return AVERROR_PATCHWELCOME;
82  }
83 
84  st->codecpar->block_align = bps * st->codecpar->channels / 8;
85 
86  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
87  return 0;
88 }
89 
91  .name = "avr",
92  .long_name = NULL_IF_CONFIG_SMALL("AVR (Audio Visual Research)"),
93  .read_probe = avr_probe,
94  .read_header = avr_read_header,
95  .read_packet = ff_pcm_read_packet,
96  .read_seek = ff_pcm_read_seek,
97  .extensions = "avr",
98  .flags = AVFMT_GENERIC_INDEX,
99 };
ff_get_pcm_codec_id
enum AVCodecID ff_get_pcm_codec_id(int bps, int flt, int be, int sflags)
Select a PCM codec based on the given parameters.
Definition: utils.c:368
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: utils.c:724
pcm.h
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
avr_read_header
static int avr_read_header(AVFormatContext *s)
Definition: avr.c:40
AVCodecParameters::channels
int channels
Audio only.
Definition: codec_par.h:166
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:468
AVInputFormat
Definition: avformat.h:626
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:631
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVFormatContext
Format I/O context.
Definition: avformat.h:1097
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:992
NULL
#define NULL
Definition: coverity.c:32
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:64
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:170
avr_probe
static int avr_probe(const AVProbeData *p)
Definition: avr.c:27
avio_rb24
unsigned int avio_rb24(AVIOContext *s)
Definition: aviobuf.c:766
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:117
bps
unsigned bps
Definition: movenc.c:1596
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:48
ff_avr_demuxer
const AVInputFormat ff_avr_demuxer
Definition: avr.c:90
AVCodecParameters::block_align
int block_align
Audio only.
Definition: codec_par.h:177
ff_pcm_read_packet
int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: pcm.c:29
AVStream
Stream structure.
Definition: avformat.h:845
ff_pcm_read_seek
int ff_pcm_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
Definition: pcm.c:56
avio_rb16
unsigned int avio_rb16(AVIOContext *s)
Definition: aviobuf.c:758
avformat.h
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:92
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: utils.c:1146
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:333
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:102
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:37
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
MKTAG
#define MKTAG(a, b, c, d)
Definition: macros.h:55
AV_RB16
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_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:98