FFmpeg
openal-dec.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2011 Jonathan Baldwin
3  *
4  * This file is part of FFmpeg.
5  *
6  * Permission to use, copy, modify, and/or distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
11  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
12  * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
13  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
14  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
15  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
16  * PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 /**
20  * @file
21  * OpenAL 1.1 capture device for libavdevice
22  **/
23 
24 #include <AL/al.h>
25 #include <AL/alc.h>
26 
27 #include "libavutil/opt.h"
28 #include "libavutil/time.h"
29 #include "libavformat/internal.h"
30 #include "avdevice.h"
31 
32 typedef struct {
33  AVClass *class;
34  /** OpenAL capture device context. **/
35  ALCdevice *device;
36  /** The number of channels in the captured audio. **/
37  int channels;
38  /** The sample rate (in Hz) of the captured audio. **/
40  /** The sample size (in bits) of the captured audio. **/
42  /** The OpenAL sample format of the captured audio. **/
43  ALCenum sample_format;
44  /** The number of bytes between two consecutive samples of the same channel/component. **/
45  ALCint sample_step;
46  /** If true, print a list of capture devices on this system and exit. **/
48 } al_data;
49 
50 typedef struct {
51  ALCenum al_fmt;
53  int channels;
55 
56 #define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
57 
58 /**
59  * Get information about an AL_FORMAT value.
60  * @param al_fmt the AL_FORMAT value to find information about.
61  * @return A pointer to a structure containing information about the AL_FORMAT value.
62  */
63 static const inline al_format_info* get_al_format_info(ALCenum al_fmt)
64 {
65  static const al_format_info info_table[] = {
66  [AL_FORMAT_MONO8-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO8, AV_CODEC_ID_PCM_U8, 1},
67  [AL_FORMAT_MONO16-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 1},
68  [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO8, AV_CODEC_ID_PCM_U8, 2},
69  [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 2},
70  };
71 
72  return &info_table[al_fmt-LOWEST_AL_FORMAT];
73 }
74 
75 /**
76  * Get the OpenAL error code, translated into an av/errno error code.
77  * @param device The ALC device to check for errors.
78  * @param error_msg_ret A pointer to a char* in which to return the error message, or NULL if desired.
79  * @return The error code, or 0 if there is no error.
80  */
81 static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
82 {
83  ALCenum error = alcGetError(device);
84  if (error_msg_ret)
85  *error_msg_ret = (const char*) alcGetString(device, error);
86  switch (error) {
87  case ALC_NO_ERROR:
88  return 0;
89  case ALC_INVALID_DEVICE:
90  return AVERROR(ENODEV);
91  break;
92  case ALC_INVALID_CONTEXT:
93  case ALC_INVALID_ENUM:
94  case ALC_INVALID_VALUE:
95  return AVERROR(EINVAL);
96  break;
97  case ALC_OUT_OF_MEMORY:
98  return AVERROR(ENOMEM);
99  break;
100  default:
101  return AVERROR(EIO);
102  }
103 }
104 
105 /**
106  * Print out a list of OpenAL capture devices on this system.
107  */
108 static inline void print_al_capture_devices(void *log_ctx)
109 {
110  const char *devices;
111 
112  if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
113  return;
114 
115  av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
116 
117  for (; *devices != '\0'; devices += strlen(devices) + 1)
118  av_log(log_ctx, AV_LOG_INFO, " %s\n", devices);
119 }
120 
122 {
123  al_data *ad = ctx->priv_data;
124  static const ALCenum sample_formats[2][2] = {
125  { AL_FORMAT_MONO8, AL_FORMAT_STEREO8 },
126  { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
127  };
128  int error = 0;
129  const char *error_msg;
130  AVStream *st = NULL;
131  AVCodecParameters *par = NULL;
132 
133  if (ad->list_devices) {
135  return AVERROR_EXIT;
136  }
137 
138  ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
139 
140  /* Open device for capture */
141  ad->device =
142  alcCaptureOpenDevice(ctx->url[0] ? ctx->url : NULL,
143  ad->sample_rate,
144  ad->sample_format,
145  ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
146 
147  if (error = al_get_error(ad->device, &error_msg)) goto fail;
148 
149  /* Create stream */
150  if (!(st = avformat_new_stream(ctx, NULL))) {
151  error = AVERROR(ENOMEM);
152  goto fail;
153  }
154 
155  /* We work in microseconds */
156  avpriv_set_pts_info(st, 64, 1, 1000000);
157 
158  /* Set codec parameters */
159  par = st->codecpar;
161  par->sample_rate = ad->sample_rate;
164 
165  /* This is needed to read the audio data */
168 
169  /* Finally, start the capture process */
170  alcCaptureStart(ad->device);
171 
172  return 0;
173 
174 fail:
175  /* Handle failure */
176  if (ad->device)
177  alcCaptureCloseDevice(ad->device);
178  if (error_msg)
179  av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
180  return error;
181 }
182 
184 {
185  al_data *ad = ctx->priv_data;
186  int error=0;
187  const char *error_msg;
188  ALCint nb_samples;
189 
190  for (;;) {
191  /* Get number of samples available */
192  alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
193  if (error = al_get_error(ad->device, &error_msg)) goto fail;
194  if (nb_samples > 0)
195  break;
196  if (ctx->flags & AVFMT_FLAG_NONBLOCK)
197  return AVERROR(EAGAIN);
198  av_usleep(1000);
199  }
200 
201  /* Create a packet of appropriate size */
202  if ((error = av_new_packet(pkt, nb_samples*ad->sample_step)) < 0)
203  goto fail;
204  pkt->pts = av_gettime();
205 
206  /* Fill the packet with the available samples */
207  alcCaptureSamples(ad->device, pkt->data, nb_samples);
208  if (error = al_get_error(ad->device, &error_msg)) goto fail;
209 
210  return pkt->size;
211 fail:
212  /* Handle failure */
213  if (pkt->data)
214  av_packet_unref(pkt);
215  if (error_msg)
216  av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
217  return error;
218 }
219 
221 {
222  al_data *ad = ctx->priv_data;
223 
224  if (ad->device) {
225  alcCaptureStop(ad->device);
226  alcCaptureCloseDevice(ad->device);
227  }
228  return 0;
229 }
230 
231 #define OFFSET(x) offsetof(al_data, x)
232 
233 static const AVOption options[] = {
234  {"channels", "set number of channels", OFFSET(channels), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AV_OPT_FLAG_DECODING_PARAM },
235  {"sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
236  {"sample_size", "set sample size", OFFSET(sample_size), AV_OPT_TYPE_INT, {.i64=16}, 8, 16, AV_OPT_FLAG_DECODING_PARAM },
237  {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
238  {"true", "", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
239  {"false", "", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
240  {NULL},
241 };
242 
243 static const AVClass class = {
244  .class_name = "openal indev",
245  .item_name = av_default_item_name,
246  .option = options,
249 };
250 
252  .name = "openal",
253  .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
254  .priv_data_size = sizeof(al_data),
255  .read_probe = NULL,
259  .flags = AVFMT_NOFILE,
260  .priv_class = &class
261 };
#define NULL
Definition: coverity.c:32
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
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:4892
channels
Definition: aptx.c:30
enum AVCodecID codec_id
Definition: qsv.c:77
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3957
static const al_format_info * get_al_format_info(ALCenum al_fmt)
Get information about an AL_FORMAT value.
Definition: openal-dec.c:63
int size
Definition: avcodec.h:1478
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
static void print_al_capture_devices(void *log_ctx)
Print out a list of OpenAL capture devices on this system.
Definition: openal-dec.c:108
int av_usleep(unsigned usec)
Sleep for a period of time.
Definition: time.c:84
static AVPacket pkt
This struct describes the properties of an encoded stream.
Definition: avcodec.h:3949
Format I/O context.
Definition: avformat.h:1358
ALCdevice * device
OpenAL capture device context.
Definition: openal-dec.c:35
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:72
#define AVFMT_FLAG_NONBLOCK
Do not block when reading packets from input.
Definition: avformat.h:1492
int sample_rate
The sample rate (in Hz) of the captured audio.
Definition: openal-dec.c:39
static int read_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition: openal-dec.c:183
AVOptions.
#define OFFSET(x)
Definition: openal-dec.c:231
#define AV_NE(be, le)
Definition: common.h:50
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4465
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1489
uint8_t * data
Definition: avcodec.h:1477
ALCenum al_fmt
Definition: openal-dec.c:51
#define av_log(a,...)
Main libavdevice API header.
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:86
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:215
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
int av_get_bits_per_sample(enum AVCodecID codec_id)
Return codec bits per sample.
Definition: utils.c:1514
ALCenum sample_format
The OpenAL sample format of the captured audio.
Definition: openal-dec.c:43
#define LOWEST_AL_FORMAT
Definition: openal-dec.c:56
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
char * url
input or output URL.
Definition: avformat.h:1454
static int read_header(AVFormatContext *ctx)
Definition: openal-dec.c:121
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3953
#define fail()
Definition: checkasm.h:120
AVFormatContext * ctx
Definition: movenc.c:48
#define AVERROR_EXIT
Immediate exit was requested; the called function should not be restarted.
Definition: error.h:56
static void error(const char *err)
int channels
The number of channels in the captured audio.
Definition: openal-dec.c:37
int64_t av_gettime(void)
Get the current time in microseconds.
Definition: time.c:39
Stream structure.
Definition: avformat.h:881
sample_rate
#define AV_LOG_INFO
Standard information.
Definition: log.h:187
static const AVOption options[]
Definition: openal-dec.c:233
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
Describe the class of an AVClass context structure.
Definition: log.h:67
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
ALCint sample_step
The number of bytes between two consecutive samples of the same channel/component.
Definition: openal-dec.c:45
int sample_size
The sample size (in bits) of the captured audio.
Definition: openal-dec.c:41
#define flags(name, subs,...)
Definition: cbs_av1.c:561
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int sample_rate
Audio only.
Definition: avcodec.h:4067
AVInputFormat ff_openal_demuxer
Definition: openal-dec.c:251
static int al_get_error(ALCdevice *device, const char **error_msg_ret)
Get the OpenAL error code, translated into an av/errno error code.
Definition: openal-dec.c:81
enum AVCodecID codec_id
Definition: openal-dec.c:52
int list_devices
If true, print a list of capture devices on this system and exit.
Definition: openal-dec.c:47
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:463
void * priv_data
Format private data.
Definition: avformat.h:1386
int channels
Audio only.
Definition: avcodec.h:4063
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
static int read_close(AVFormatContext *ctx)
Definition: openal-dec.c:220
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
This structure stores compressed data.
Definition: avcodec.h:1454
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1470