FFmpeg: libavformat/apc.c Source File

FFmpeg

libavformat

apc.c

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1 /*

2 * CRYO APC audio format demuxer

3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>

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 <string.h>

23

24 #include "libavutil/channel_layout.h"

25 #include "avformat.h"

26 #include "demux.h"

27

28 static int apc_probe(const AVProbeData *p)

29 {

30 if (!strncmp(p->buf, "CRYO_APC", 8))

31 return AVPROBE_SCORE_MAX;

32

33 return 0;

34 }

35

36 static int apc_read_header(AVFormatContext *s)

37 {

38 AVIOContext *pb = s->pb;

39 AVStream *st;

40 int ret;

41 int channels;

42

43 avio_rl32(pb); /* CRYO */

44 avio_rl32(pb); /* _APC */

45 avio_rl32(pb); /* 1.20 */

46

47 st = avformat_new_stream(s, NULL);

48 if (!st)

49 return AVERROR(ENOMEM);

50

51 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

52 st->codecpar->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;

53

54 avio_rl32(pb); /* number of samples */

55 st->codecpar->sample_rate = avio_rl32(pb);

56

57 /* initial predictor values for adpcm decoder */

58 if ((ret = ff_get_extradata(s, st->codecpar, pb, 2 * 4)) < 0)

59 return ret;

60

61 channels = !!avio_rl32(pb) + 1;

62 av_channel_layout_default(&st->codecpar->ch_layout, channels);

63

64 st->codecpar->bits_per_coded_sample = 4;

65 st->codecpar->bit_rate = (int64_t)st->codecpar->bits_per_coded_sample * channels

66 * st->codecpar->sample_rate;

67 st->codecpar->block_align = 1;

68

69 return 0;

70 }

71

72 #define MAX_READ_SIZE 4096

73

74 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)

75 {

76 if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)

77 return AVERROR(EIO);

78 pkt->stream_index = 0;

79 return 0;

80 }

81

82 const AVInputFormat ff_apc_demuxer = {

83 .name = "apc",

84 .long_name = NULL_IF_CONFIG_SMALL("CRYO APC"),

85 .read_probe = apc_probe,

86 .read_header = apc_read_header,

87 .read_packet = apc_read_packet,

88 };

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:237

AVCodecParameters::codec_type

enum AVMediaType codec_type

General type of the encoded data.

Definition: codec_par.h:57

apc_read_packet

static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)

Definition: apc.c:74

const AVInputFormat ff_apc_demuxer

Definition: apc.c:82

ff_get_extradata

int ff_get_extradata(void *logctx, AVCodecParameters *par, AVIOContext *pb, int size)

Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end which is always set to 0 and f...

Definition: demux_utils.c:355

AVPROBE_SCORE_MAX

#define AVPROBE_SCORE_MAX

maximum score

Definition: avformat.h:465

AVPacket * pkt

Definition: movenc.c:59

Definition: avformat.h:656

s

#define s(width, name)

Definition: cbs_vp9.c:256

AVInputFormat::name

const char * name

A comma separated list of short names for the format.

Definition: avformat.h:661

AVProbeData::buf

unsigned char * buf

Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.

Definition: avformat.h:455

AVMEDIA_TYPE_AUDIO

@ AVMEDIA_TYPE_AUDIO

Definition: avutil.h:202

AV_CODEC_ID_ADPCM_IMA_APC

@ AV_CODEC_ID_ADPCM_IMA_APC

Definition: codec_id.h:386

channels

Definition: aptx.h:32

static int apc_probe(const AVProbeData *p)

Definition: apc.c:28

AVFormatContext

Format I/O context.

Definition: avformat.h:1213

AVStream::codecpar

AVCodecParameters * codecpar

Codec parameters associated with this stream.

Definition: avformat.h:1108

#define NULL

Definition: coverity.c:32

This structure contains the data a format has to probe a file.

Definition: avformat.h:453

av_channel_layout_default

void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels)

Get the default channel layout for a given number of channels.

Definition: channel_layout.c:960

AVCodecParameters::ch_layout

AVChannelLayout ch_layout

Audio only.

Definition: codec_par.h:212

AVCodecParameters::sample_rate

int sample_rate

Audio only.

Definition: codec_par.h:177

unsigned int avio_rl32(AVIOContext *s)

Definition: aviobuf.c:759

Bytestream IO Context.

Definition: avio.h:162

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

apc_read_header

static int apc_read_header(AVFormatContext *s)

Definition: apc.c:36

AVCodecParameters::block_align

int block_align

Audio only.

Definition: codec_par.h:184

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

Definition: filter_design.txt:187

Stream structure.

Definition: avformat.h:948

channel_layout.h

AVPacket::stream_index

int stream_index

Definition: packet.h:376

AVCodecParameters::bits_per_coded_sample

int bits_per_coded_sample

The number of bits per sample in the codedwords.

Definition: codec_par.h:103

AVCodecParameters::codec_id

enum AVCodecID codec_id

Specific type of the encoded data (the codec used).

Definition: codec_par.h:61

This structure stores compressed data.

Definition: packet.h:351

AVCodecParameters::bit_rate

int64_t bit_rate

The average bitrate of the encoded data (in bits per second).

Definition: codec_par.h:90

#define MAX_READ_SIZE

Definition: apc.c:72

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