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"
32 /** OpenAL capture device context. **/
34 /** The number of channels in the captured audio. **/
36 /** The sample rate (in Hz) of the captured audio. **/
38 /** The sample size (in bits) of the captured audio. **/
40 /** The OpenAL sample format of the captured audio. **/
41 ALCenum sample_format;
42 /** The number of bytes between two consecutive samples of the same channel/component. **/
44 /** If true, print a list of capture devices on this system and exit. **/
50 enum CodecID codec_id;
54 #define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
57 * Get information about an AL_FORMAT value.
58 * @param al_fmt the AL_FORMAT value to find information about.
59 * @return A pointer to a structure containing information about the AL_FORMAT value.
61 static inline al_format_info* get_al_format_info(ALCenum al_fmt)
63 static al_format_info info_table[] = {
64 [AL_FORMAT_MONO8-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO8, CODEC_ID_PCM_U8, 1},
65 [AL_FORMAT_MONO16-LOWEST_AL_FORMAT] = {AL_FORMAT_MONO16, AV_NE (CODEC_ID_PCM_S16BE, CODEC_ID_PCM_S16LE), 1},
66 [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO8, CODEC_ID_PCM_U8, 2},
67 [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (CODEC_ID_PCM_S16BE, CODEC_ID_PCM_S16LE), 2},
70 return &info_table[al_fmt-LOWEST_AL_FORMAT];
74 * Get the OpenAL error code, translated into an av/errno error code.
75 * @param device The ALC device to check for errors.
76 * @param error_msg_ret A pointer to a char* in which to return the error message, or NULL if desired.
77 * @return The error code, or 0 if there is no error.
79 static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
81 ALCenum error = alcGetError(device);
83 *error_msg_ret = (const char*) alcGetString(device, error);
87 case ALC_INVALID_DEVICE:
88 return AVERROR(ENODEV);
90 case ALC_INVALID_CONTEXT:
91 case ALC_INVALID_ENUM:
92 case ALC_INVALID_VALUE:
93 return AVERROR(EINVAL);
95 case ALC_OUT_OF_MEMORY:
96 return AVERROR(ENOMEM);
104 * Print out a list of OpenAL capture devices on this system.
106 static inline void print_al_capture_devices(void *log_ctx)
110 if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
113 av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
115 for (; *devices != '\0'; devices += strlen(devices) + 1)
116 av_log(log_ctx, AV_LOG_INFO, " %s\n", devices);
119 static int read_header(AVFormatContext *ctx, AVFormatParameters *ap)
121 al_data *ad = ctx->priv_data;
122 static const ALCenum sample_formats[2][2] = {
123 { AL_FORMAT_MONO8, AL_FORMAT_STEREO8 },
124 { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
127 const char *error_msg;
129 AVCodecContext *codec = NULL;
131 if (ad->list_devices) {
132 print_al_capture_devices(ctx);
136 ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
138 /* Open device for capture */
140 alcCaptureOpenDevice(ctx->filename[0] ? ctx->filename : NULL,
143 ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
145 if (error = al_get_error(ad->device, &error_msg)) goto fail;
148 if (!(st = av_new_stream(ctx, 0))) {
149 error = AVERROR(ENOMEM);
153 /* We work in microseconds */
154 av_set_pts_info(st, 64, 1, 1000000);
156 /* Set codec parameters */
158 codec->codec_type = AVMEDIA_TYPE_AUDIO;
159 codec->sample_rate = ad->sample_rate;
160 codec->channels = get_al_format_info(ad->sample_format)->channels;
161 codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
163 /* This is needed to read the audio data */
164 ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
165 get_al_format_info(ad->sample_format)->channels) / 8;
167 /* Finally, start the capture process */
168 alcCaptureStart(ad->device);
175 alcCaptureCloseDevice(ad->device);
177 av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
181 static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
183 al_data *ad = ctx->priv_data;
185 const char *error_msg;
188 /* Get number of samples available */
189 alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
190 if (error = al_get_error(ad->device, &error_msg)) goto fail;
192 /* Create a packet of appropriate size */
193 av_new_packet(pkt, nb_samples*ad->sample_step);
194 pkt->pts = av_gettime();
196 /* Fill the packet with the available samples */
197 alcCaptureSamples(ad->device, pkt->data, nb_samples);
198 if (error = al_get_error(ad->device, &error_msg)) goto fail;
204 av_destruct_packet(pkt);
206 av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
210 static int read_close(AVFormatContext* ctx)
212 al_data *ad = ctx->priv_data;
215 alcCaptureStop(ad->device);
216 alcCaptureCloseDevice(ad->device);
221 #define OFFSET(x) offsetof(al_data, x)
223 static const AVOption options[] = {
224 {"channels", "set number of channels", OFFSET(channels), AV_OPT_TYPE_INT, {.dbl=2}, 1, 2, AV_OPT_FLAG_DECODING_PARAM },
225 {"sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.dbl=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
226 {"sample_size", "set sample size", OFFSET(sample_size), AV_OPT_TYPE_INT, {.dbl=16}, 8, 16, AV_OPT_FLAG_DECODING_PARAM },
227 {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.dbl=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
228 {"true", "", 0, AV_OPT_TYPE_CONST, {.dbl=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
229 {"false", "", 0, AV_OPT_TYPE_CONST, {.dbl=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
233 static const AVClass class = {
234 .class_name = "openal",
235 .item_name = av_default_item_name,
237 .version = LIBAVUTIL_VERSION_INT
240 AVInputFormat ff_openal_demuxer = {
242 .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
243 .priv_data_size = sizeof(al_data),
245 .read_header = read_header,
246 .read_packet = read_packet,
247 .read_close = read_close,
248 .flags = AVFMT_NOFILE,