FFmpeg
alsa_enc.c
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1 /*
2  * ALSA input and output
3  * Copyright (c) 2007 Luca Abeni ( lucabe72 email it )
4  * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr )
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 /**
24  * @file
25  * ALSA input and output: output
26  * @author Luca Abeni ( lucabe72 email it )
27  * @author Benoit Fouet ( benoit fouet free fr )
28  *
29  * This avdevice encoder can play audio to an ALSA (Advanced Linux
30  * Sound Architecture) device.
31  *
32  * The filename parameter is the name of an ALSA PCM device capable of
33  * capture, for example "default" or "plughw:1"; see the ALSA documentation
34  * for naming conventions. The empty string is equivalent to "default".
35  *
36  * The playback period is set to the lower value available for the device,
37  * which gives a low latency suitable for real-time playback.
38  */
39 
40 #include <alsa/asoundlib.h>
41 
42 #include "libavutil/frame.h"
43 #include "libavutil/internal.h"
44 #include "libavutil/time.h"
45 
46 
47 #include "libavformat/internal.h"
48 #include "libavformat/mux.h"
49 #include "avdevice.h"
50 #include "alsa.h"
51 
53 {
54  AlsaData *s = s1->priv_data;
55  AVStream *st = NULL;
56  unsigned int sample_rate;
57  enum AVCodecID codec_id;
58  int res;
59 
60  if (s1->nb_streams != 1 || s1->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO) {
61  av_log(s1, AV_LOG_ERROR, "Only a single audio stream is supported.\n");
62  return AVERROR(EINVAL);
63  }
64  st = s1->streams[0];
65 
67  codec_id = st->codecpar->codec_id;
68  res = ff_alsa_open(s1, SND_PCM_STREAM_PLAYBACK, &sample_rate,
70  if (sample_rate != st->codecpar->sample_rate) {
72  "sample rate %d not available, nearest is %d\n",
74  goto fail;
75  }
76  avpriv_set_pts_info(st, 64, 1, sample_rate);
77 
78  return res;
79 
80 fail:
81  snd_pcm_close(s->h);
82  return AVERROR(EIO);
83 }
84 
86 {
87  AlsaData *s = s1->priv_data;
88  int res;
89  int size = pkt->size;
90  const uint8_t *buf = pkt->data;
91 
92  size /= s->frame_size;
93  if (pkt->dts != AV_NOPTS_VALUE)
94  s->timestamp = pkt->dts;
95  s->timestamp += pkt->duration ? pkt->duration : size;
96 
97  if (s->reorder_func) {
98  if (size > s->reorder_buf_size)
100  return AVERROR(ENOMEM);
101  s->reorder_func(buf, s->reorder_buf, size);
102  buf = s->reorder_buf;
103  }
104  while ((res = snd_pcm_writei(s->h, buf, size)) < 0) {
105  if (res == -EAGAIN) {
106 
107  return AVERROR(EAGAIN);
108  }
109 
110  if (ff_alsa_xrun_recover(s1, res) < 0) {
111  av_log(s1, AV_LOG_ERROR, "ALSA write error: %s\n",
112  snd_strerror(res));
113 
114  return AVERROR(EIO);
115  }
116  }
117 
118  return 0;
119 }
120 
121 static int audio_write_frame(AVFormatContext *s1, int stream_index,
122  AVFrame **frame, unsigned flags)
123 {
124  AlsaData *s = s1->priv_data;
125  AVPacket pkt;
126 
127  /* ff_alsa_open() should have accepted only supported formats */
129  return av_sample_fmt_is_planar(s1->streams[stream_index]->codecpar->format) ?
130  AVERROR(EINVAL) : 0;
131  /* set only used fields */
132  pkt.data = (*frame)->data[0];
133  pkt.size = (*frame)->nb_samples * s->frame_size;
134  pkt.dts = (*frame)->pkt_dts;
135 #if FF_API_PKT_DURATION
137  if ((*frame)->pkt_duration)
138  pkt.duration = (*frame)->pkt_duration;
139  else
141 #endif
142  pkt.duration = (*frame)->duration;
143  return audio_write_packet(s1, &pkt);
144 }
145 
146 static void
148  int64_t *dts, int64_t *wall)
149 {
150  AlsaData *s = s1->priv_data;
151  snd_pcm_sframes_t delay = 0;
152  *wall = av_gettime();
153  snd_pcm_delay(s->h, &delay);
154  *dts = s->timestamp - delay;
155 }
156 
158 {
159  return ff_alsa_get_device_list(device_list, SND_PCM_STREAM_PLAYBACK);
160 }
161 
162 static const AVClass alsa_muxer_class = {
163  .class_name = "ALSA outdev",
164  .item_name = av_default_item_name,
165  .version = LIBAVUTIL_VERSION_INT,
167 };
168 
170  .p.name = "alsa",
171  .p.long_name = NULL_IF_CONFIG_SMALL("ALSA audio output"),
172  .priv_data_size = sizeof(AlsaData),
173  .p.audio_codec = DEFAULT_CODEC_ID,
174  .p.video_codec = AV_CODEC_ID_NONE,
175  .write_header = audio_write_header,
176  .write_packet = audio_write_packet,
177  .write_trailer = ff_alsa_close,
178  .write_uncoded_frame = audio_write_frame,
179  .get_device_list = audio_get_device_list,
180  .get_output_timestamp = audio_get_output_timestamp,
181  .p.flags = AVFMT_NOFILE,
182  .p.priv_class = &alsa_muxer_class,
183 };
FF_ENABLE_DEPRECATION_WARNINGS
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:73
AVOutputFormat::name
const char * name
Definition: avformat.h:511
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
audio_write_frame
static int audio_write_frame(AVFormatContext *s1, int stream_index, AVFrame **frame, unsigned flags)
Definition: alsa_enc.c:121
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
AVPacket::data
uint8_t * data
Definition: packet.h:522
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:540
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:323
sample_rate
sample_rate
Definition: ffmpeg_filter.c:424
audio_get_output_timestamp
static void audio_get_output_timestamp(AVFormatContext *s1, int stream, int64_t *dts, int64_t *wall)
Definition: alsa_enc.c:147
FFOutputFormat::p
AVOutputFormat p
The public AVOutputFormat.
Definition: mux.h:36
DEFAULT_CODEC_ID
#define DEFAULT_CODEC_ID
Definition: alsa.h:42
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:843
fail
#define fail()
Definition: checkasm.h:179
audio_write_packet
static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt)
Definition: alsa_enc.c:85
ff_alsa_muxer
const FFOutputFormat ff_alsa_muxer
Definition: alsa_enc.c:169
alsa_muxer_class
static const AVClass alsa_muxer_class
Definition: alsa_enc.c:162
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
av_cold
#define av_cold
Definition: attributes.h:90
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
s1
#define s1
Definition: regdef.h:38
av_sample_fmt_is_planar
int av_sample_fmt_is_planar(enum AVSampleFormat sample_fmt)
Check if the sample format is planar.
Definition: samplefmt.c:114
ff_alsa_open
av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode, unsigned int *sample_rate, int channels, enum AVCodecID *codec_id)
Open an ALSA PCM.
Definition: alsa.c:172
ff_alsa_extend_reorder_buf
int ff_alsa_extend_reorder_buf(AlsaData *s, int min_size)
Definition: alsa.c:345
codec_id
enum AVCodecID codec_id
Definition: vaapi_decode.c:389
frame
static AVFrame * frame
Definition: demux_decode.c:54
AVFormatContext
Format I/O context.
Definition: avformat.h:1363
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:864
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
AlsaData
Definition: alsa.h:48
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:237
FFOutputFormat
Definition: mux.h:32
time.h
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:206
ff_alsa_close
av_cold int ff_alsa_close(AVFormatContext *s1)
Close the ALSA PCM.
Definition: alsa.c:308
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:171
AVCodecID
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: codec_id.h:49
AVPacket::size
int size
Definition: packet.h:523
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:106
size
int size
Definition: twinvq_data.h:10344
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
AVFMT_NOFILE
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:469
frame.h
avdevice.h
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:521
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:50
internal.h
AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT
@ AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT
Definition: log.h:42
alsa.h
AVStream
Stream structure.
Definition: avformat.h:841
AVClass::class_name
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:71
AVDeviceInfoList
List of devices.
Definition: avdevice.h:343
AV_WRITE_UNCODED_FRAME_QUERY
@ AV_WRITE_UNCODED_FRAME_QUERY
Query whether the feature is possible on this stream.
Definition: mux.h:210
ff_alsa_xrun_recover
int ff_alsa_xrun_recover(AVFormatContext *s1, int err)
Try to recover from ALSA buffer underrun.
Definition: alsa.c:324
av_gettime
int64_t av_gettime(void)
Get the current time in microseconds.
Definition: time.c:39
FF_DISABLE_DEPRECATION_WARNINGS
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:72
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:499
ff_alsa_get_device_list
int ff_alsa_get_device_list(AVDeviceInfoList *device_list, snd_pcm_stream_t stream_type)
Definition: alsa.c:362
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:474
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
h
h
Definition: vp9dsp_template.c:2038
audio_write_header
static av_cold int audio_write_header(AVFormatContext *s1)
Definition: alsa_enc.c:52
mux.h
audio_get_device_list
static int audio_get_device_list(AVFormatContext *h, AVDeviceInfoList *device_list)
Definition: alsa_enc.c:157