FFmpeg: libavdevice/openal-dec.c Source File

FFmpeg
openal-dec.c
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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. **/
39   int sample_rate;
40  /** The sample size (in bits) of the captured audio. **/
41   int sample_size;
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. **/
47   int list_devices;
48 } al_data;
49 
50  typedef struct {
51   ALCenum al_fmt;
52   enum AVCodecID codec_id;
53   int channels;
54 } al_format_info;
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 inline al_format_info* get_al_format_info(ALCenum al_fmt)
64 {
65  static 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円'; devices += strlen(devices) + 1)
118  av_log(log_ctx, AV_LOG_INFO, " %s\n", devices);
119 }
120 
121  static int read_header(AVFormatContext *ctx)
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  AVCodecContext *codec = NULL;
132 
133  if (ad->list_devices) {
134  print_al_capture_devices(ctx);
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->filename[0] ? ctx->filename : 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  codec = st->codec;
160  codec->codec_type = AVMEDIA_TYPE_AUDIO;
161  codec->sample_rate = ad->sample_rate;
162  codec->channels = get_al_format_info(ad->sample_format)->channels;
163  codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
164 
165  /* This is needed to read the audio data */
166  ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
167  get_al_format_info(ad->sample_format)->channels) / 8;
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 
183  static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
184 {
185  al_data *ad = ctx->priv_data;
186  int error=0;
187  const char *error_msg;
188  ALCint nb_samples;
189 
190  /* Get number of samples available */
191  alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
192  if (error = al_get_error(ad->device, &error_msg)) goto fail;
193 
194  /* Create a packet of appropriate size */
195  if ((error = av_new_packet(pkt, nb_samples*ad->sample_step)) < 0)
196  goto fail;
197  pkt->pts = av_gettime();
198 
199  /* Fill the packet with the available samples */
200  alcCaptureSamples(ad->device, pkt->data, nb_samples);
201  if (error = al_get_error(ad->device, &error_msg)) goto fail;
202 
203  return pkt->size;
204 fail:
205  /* Handle failure */
206  if (pkt->data)
207  av_destruct_packet(pkt);
208  if (error_msg)
209  av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
210  return error;
211 }
212 
213  static int read_close(AVFormatContext* ctx)
214 {
215  al_data *ad = ctx->priv_data;
216 
217  if (ad->device) {
218  alcCaptureStop(ad->device);
219  alcCaptureCloseDevice(ad->device);
220  }
221  return 0;
222 }
223 
224  #define OFFSET(x) offsetof(al_data, x)
225 
226  static const AVOption options[] = {
227  {"channels", "set number of channels", OFFSET(channels), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AV_OPT_FLAG_DECODING_PARAM },
228  {"sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
229  {"sample_size", "set sample size", OFFSET(sample_size), AV_OPT_TYPE_INT, {.i64=16}, 8, 16, AV_OPT_FLAG_DECODING_PARAM },
230  {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
231  {"true", "", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
232  {"false", "", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
233  {NULL},
234 };
235 
236 static const AVClass class = {
237   .class_name = "openal",
238   .item_name = av_default_item_name,
239   .option = options,
240   .version = LIBAVUTIL_VERSION_INT,
241   .category = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
242 };
243 
244  AVInputFormat ff_openal_demuxer = {
245  .name = "openal",
246  .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
247  .priv_data_size = sizeof(al_data),
248  .read_probe = NULL,
249  .read_header = read_header,
250  .read_packet = read_packet,
251  .read_close = read_close,
252  .flags = AVFMT_NOFILE,
253  .priv_class = &class
254 };
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