2 * Copyright (c) 2011 Jonathan Baldwin
4 * This file is part of FFmpeg.
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.
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.
21 * OpenAL 1.1 capture device for libavdevice
27 #include "libavutil/opt.h"
28 #include "libavformat/internal.h"
33 /** OpenAL capture device context. **/
35 /** The number of channels in the captured audio. **/
37 /** The sample rate (in Hz) of the captured audio. **/
39 /** The sample size (in bits) of the captured audio. **/
41 /** The OpenAL sample format of the captured audio. **/
42 ALCenum sample_format;
43 /** The number of bytes between two consecutive samples of the same channel/component. **/
45 /** If true, print a list of capture devices on this system and exit. **/
51 enum AVCodecID codec_id;
55 #define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
58 * Get information about an AL_FORMAT value.
59 * @param al_fmt the AL_FORMAT value to find information about.
60 * @return A pointer to a structure containing information about the AL_FORMAT value.
62 static inline al_format_info* get_al_format_info(ALCenum al_fmt)
64 static al_format_info info_table[] = {
65 [AL_FORMAT_MONO8-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO8, AV_CODEC_ID_PCM_U8, 1},
66 [AL_FORMAT_MONO16-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 1},
67 [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO8, AV_CODEC_ID_PCM_U8, 2},
68 [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 2},
71 return &info_table[al_fmt-LOWEST_AL_FORMAT];
75 * Get the OpenAL error code, translated into an av/errno error code.
76 * @param device The ALC device to check for errors.
77 * @param error_msg_ret A pointer to a char* in which to return the error message, or NULL if desired.
78 * @return The error code, or 0 if there is no error.
80 static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
82 ALCenum error = alcGetError(device);
84 *error_msg_ret = (const char*) alcGetString(device, error);
88 case ALC_INVALID_DEVICE:
89 return AVERROR(ENODEV);
91 case ALC_INVALID_CONTEXT:
92 case ALC_INVALID_ENUM:
93 case ALC_INVALID_VALUE:
94 return AVERROR(EINVAL);
96 case ALC_OUT_OF_MEMORY:
97 return AVERROR(ENOMEM);
105 * Print out a list of OpenAL capture devices on this system.
107 static inline void print_al_capture_devices(void *log_ctx)
111 if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
114 av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
116 for (; *devices != '\0'; devices += strlen(devices) + 1)
117 av_log(log_ctx, AV_LOG_INFO, " %s\n", devices);
120 static int read_header(AVFormatContext *ctx)
122 al_data *ad = ctx->priv_data;
123 static const ALCenum sample_formats[2][2] = {
124 { AL_FORMAT_MONO8, AL_FORMAT_STEREO8 },
125 { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
128 const char *error_msg;
130 AVCodecContext *codec = NULL;
132 if (ad->list_devices) {
133 print_al_capture_devices(ctx);
137 ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
139 /* Open device for capture */
141 alcCaptureOpenDevice(ctx->filename[0] ? ctx->filename : NULL,
144 ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
146 if (error = al_get_error(ad->device, &error_msg)) goto fail;
149 if (!(st = avformat_new_stream(ctx, NULL))) {
150 error = AVERROR(ENOMEM);
154 /* We work in microseconds */
155 avpriv_set_pts_info(st, 64, 1, 1000000);
157 /* Set codec parameters */
159 codec->codec_type = AVMEDIA_TYPE_AUDIO;
160 codec->sample_rate = ad->sample_rate;
161 codec->channels = get_al_format_info(ad->sample_format)->channels;
162 codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
164 /* This is needed to read the audio data */
165 ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
166 get_al_format_info(ad->sample_format)->channels) / 8;
168 /* Finally, start the capture process */
169 alcCaptureStart(ad->device);
176 alcCaptureCloseDevice(ad->device);
178 av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
182 static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
184 al_data *ad = ctx->priv_data;
186 const char *error_msg;
189 /* Get number of samples available */
190 alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
191 if (error = al_get_error(ad->device, &error_msg)) goto fail;
193 /* Create a packet of appropriate size */
194 av_new_packet(pkt, nb_samples*ad->sample_step);
195 pkt->pts = av_gettime();
197 /* Fill the packet with the available samples */
198 alcCaptureSamples(ad->device, pkt->data, nb_samples);
199 if (error = al_get_error(ad->device, &error_msg)) goto fail;
205 av_destruct_packet(pkt);
207 av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
211 static int read_close(AVFormatContext* ctx)
213 al_data *ad = ctx->priv_data;
216 alcCaptureStop(ad->device);
217 alcCaptureCloseDevice(ad->device);
222 #define OFFSET(x) offsetof(al_data, x)
224 static const AVOption options[] = {
225 {"channels", "set number of channels", OFFSET(channels), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AV_OPT_FLAG_DECODING_PARAM },
226 {"sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
227 {"sample_size", "set sample size", OFFSET(sample_size), AV_OPT_TYPE_INT, {.i64=16}, 8, 16, AV_OPT_FLAG_DECODING_PARAM },
228 {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
229 {"true", "", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
230 {"false", "", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
234 static const AVClass class = {
235 .class_name = "openal",
236 .item_name = av_default_item_name,
238 .version = LIBAVUTIL_VERSION_INT
241 AVInputFormat ff_openal_demuxer = {
243 .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
244 .priv_data_size = sizeof(al_data),
246 .read_header = read_header,
247 .read_packet = read_packet,
248 .read_close = read_close,
249 .flags = AVFMT_NOFILE,