FFmpeg: libavformat/wvedec.c Source File

FFmpeg

libavformat

wvedec.c

Go to the documentation of this file.

1 /*

2 * Copyright (c) 2015 Paul B Mahol

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 "avformat.h"

22 #include "internal.h"

23 #include "pcm.h"

24

25 static int wve_probe(const AVProbeData *p)

26 {

27 if (memcmp(p->buf, "ALawSoundFile**0円017円020円", 18) ||

28 memcmp(p->buf + 22, "0円0円0円1円0円0円0円0円0円0円", 10))

29 return 0;

30 return AVPROBE_SCORE_MAX;

31 }

32

33 static int wve_read_header(AVFormatContext *s)

34 {

35 AVStream *st;

36

37 st = avformat_new_stream(s, NULL);

38 if (!st)

39 return AVERROR(ENOMEM);

40

41 avio_skip(s->pb, 18);

42 st->duration = avio_rb32(s->pb);

43 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

44 st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW;

45 st->codecpar->sample_rate = 8000;

46 st->codecpar->ch_layout.nb_channels = 1;

47 st->codecpar->bits_per_coded_sample = av_get_bits_per_sample(st->codecpar->codec_id);

48 st->codecpar->block_align = st->codecpar->bits_per_coded_sample *

49 st->codecpar->ch_layout.nb_channels / 8;

50 avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);

51 avio_skip(s->pb, 10);

52

53 return 0;

54 }

55

56 const AVInputFormat ff_wve_demuxer = {

57 .name = "wve",

58 .long_name = NULL_IF_CONFIG_SMALL("Psion 3 audio"),

59 .read_probe = wve_probe,

60 .read_header = wve_read_header,

61 .read_packet = ff_pcm_read_packet,

62 .read_seek = ff_pcm_read_seek,

63 };

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

AVChannelLayout::nb_channels

int nb_channels

Number of channels in this layout.

Definition: channel_layout.h:311

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

AVStream::duration

int64_t duration

Decoding: duration of the stream, in stream time base.

Definition: avformat.h:897

av_get_bits_per_sample

int av_get_bits_per_sample(enum AVCodecID codec_id)

Return codec bits per sample.

Definition: utils.c:583

unsigned int avio_rb32(AVIOContext *s)

Definition: aviobuf.c:782

Definition: avformat.h:546

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:551

AVProbeData::buf

unsigned char * buf

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

Definition: avformat.h:453

AVMEDIA_TYPE_AUDIO

@ AVMEDIA_TYPE_AUDIO

Definition: avutil.h:202

AVFormatContext

Format I/O context.

Definition: avformat.h:1104

AV_CODEC_ID_PCM_ALAW

@ AV_CODEC_ID_PCM_ALAW

Definition: codec_id.h:333

AVStream::codecpar

AVCodecParameters * codecpar

Codec parameters associated with this stream.

Definition: avformat.h:861

#define NULL

Definition: coverity.c:32

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

Definition: avformat.h:451

AVCodecParameters::ch_layout

AVChannelLayout ch_layout

Audio only.

Definition: codec_par.h:213

AVCodecParameters::sample_rate

int sample_rate

Audio only.

Definition: codec_par.h:178

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

static int wve_probe(const AVProbeData *p)

Definition: wvedec.c:25

AVCodecParameters::block_align

int block_align

Audio only.

Definition: codec_par.h:185

wve_read_header

static int wve_read_header(AVFormatContext *s)

Definition: wvedec.c:33

ff_pcm_read_packet

int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)

Definition: pcm.c:29

const AVInputFormat ff_wve_demuxer

Definition: wvedec.c:56

Stream structure.

Definition: avformat.h:838

ff_pcm_read_seek

int ff_pcm_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)

Definition: pcm.c:56

int64_t avio_skip(AVIOContext *s, int64_t offset)

Skip given number of bytes forward.

Definition: aviobuf.c:339

AVCodecParameters::bits_per_coded_sample

int bits_per_coded_sample

The number of bits per sample in the codedwords.

Definition: codec_par.h:104

AVCodecParameters::codec_id

enum AVCodecID codec_id

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

Definition: codec_par.h:62

Generated on Tue Feb 28 2023 21:34:11 for FFmpeg by doxygen 1.8.17