libavdevice/openal-dec.c
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00001 /*
00002  * Copyright (c) 2011 Jonathan Baldwin
00003  *
00004  * This file is part of FFmpeg.
00005  *
00006  * Permission to use, copy, modify, and/or distribute this software for any
00007  * purpose with or without fee is hereby granted, provided that the above
00008  * copyright notice and this permission notice appear in all copies.
00009  *
00010  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
00011  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
00012  * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
00013  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
00014  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
00015  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
00016  * PERFORMANCE OF THIS SOFTWARE.
00017  */
00018 
00024 #include <AL/al.h>
00025 #include <AL/alc.h>
00026 
00027 #include "libavutil/opt.h"
00028 #include "libavformat/internal.h"
00029 #include "avdevice.h"
00030 
00031 typedef struct {
00032     AVClass *class;
00034     ALCdevice *device;
00036     int channels;
00038     int sample_rate;
00040     int sample_size;
00042     ALCenum sample_format;
00044     ALCint sample_step;
00046     int list_devices;
00047 } al_data;
00048 
00049 typedef struct {
00050     ALCenum al_fmt;
00051     enum CodecID codec_id;
00052     int channels;
00053 } al_format_info;
00054 
00055 #define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
00056 
00062 static inline al_format_info* get_al_format_info(ALCenum al_fmt)
00063 {
00064     static al_format_info info_table[] = {
00065         [AL_FORMAT_MONO8-LOWEST_AL_FORMAT]    = {AL_FORMAT_MONO8, CODEC_ID_PCM_U8, 1},
00066         [AL_FORMAT_MONO16-LOWEST_AL_FORMAT]   = {AL_FORMAT_MONO16, AV_NE (CODEC_ID_PCM_S16BE, CODEC_ID_PCM_S16LE), 1},
00067         [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT]  = {AL_FORMAT_STEREO8, CODEC_ID_PCM_U8, 2},
00068         [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (CODEC_ID_PCM_S16BE, CODEC_ID_PCM_S16LE), 2},
00069     };
00070 
00071     return &info_table[al_fmt-LOWEST_AL_FORMAT];
00072 }
00073 
00080 static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
00081 {
00082     ALCenum error = alcGetError(device);
00083     if (error_msg_ret)
00084         *error_msg_ret = (const char*) alcGetString(device, error);
00085     switch (error) {
00086     case ALC_NO_ERROR:
00087         return 0;
00088     case ALC_INVALID_DEVICE:
00089         return AVERROR(ENODEV);
00090         break;
00091     case ALC_INVALID_CONTEXT:
00092     case ALC_INVALID_ENUM:
00093     case ALC_INVALID_VALUE:
00094         return AVERROR(EINVAL);
00095         break;
00096     case ALC_OUT_OF_MEMORY:
00097         return AVERROR(ENOMEM);
00098         break;
00099     default:
00100         return AVERROR(EIO);
00101     }
00102 }
00103 
00107 static inline void print_al_capture_devices(void *log_ctx)
00108 {
00109     const char *devices;
00110 
00111     if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
00112         return;
00113 
00114     av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
00115 
00116     for (; *devices != '\0'; devices += strlen(devices) + 1)
00117         av_log(log_ctx, AV_LOG_INFO, "  %s\n", devices);
00118 }
00119 
00120 static int read_header(AVFormatContext *ctx, AVFormatParameters *ap)
00121 {
00122     al_data *ad = ctx->priv_data;
00123     static const ALCenum sample_formats[2][2] = {
00124         { AL_FORMAT_MONO8,  AL_FORMAT_STEREO8  },
00125         { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
00126     };
00127     int error = 0;
00128     const char *error_msg;
00129     AVStream *st = NULL;
00130     AVCodecContext *codec = NULL;
00131 
00132     if (ad->list_devices) {
00133         print_al_capture_devices(ctx);
00134         return AVERROR_EXIT;
00135     }
00136 
00137     ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
00138 
00139     /* Open device for capture */
00140     ad->device =
00141         alcCaptureOpenDevice(ctx->filename[0] ? ctx->filename : NULL,
00142                              ad->sample_rate,
00143                              ad->sample_format,
00144                              ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
00145 
00146     if (error = al_get_error(ad->device, &error_msg)) goto fail;
00147 
00148     /* Create stream */
00149     if (!(st = avformat_new_stream(ctx, NULL))) {
00150         error = AVERROR(ENOMEM);
00151         goto fail;
00152     }
00153 
00154     /* We work in microseconds */
00155     avpriv_set_pts_info(st, 64, 1, 1000000);
00156 
00157     /* Set codec parameters */
00158     codec = st->codec;
00159     codec->codec_type = AVMEDIA_TYPE_AUDIO;
00160     codec->sample_rate = ad->sample_rate;
00161     codec->channels = get_al_format_info(ad->sample_format)->channels;
00162     codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
00163 
00164     /* This is needed to read the audio data */
00165     ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
00166                        get_al_format_info(ad->sample_format)->channels) / 8;
00167 
00168     /* Finally, start the capture process */
00169     alcCaptureStart(ad->device);
00170 
00171     return 0;
00172 
00173 fail:
00174     /* Handle failure */
00175     if (ad->device)
00176         alcCaptureCloseDevice(ad->device);
00177     if (error_msg)
00178         av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
00179     return error;
00180 }
00181 
00182 static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
00183 {
00184     al_data *ad = ctx->priv_data;
00185     int error=0;
00186     const char *error_msg;
00187     ALCint nb_samples;
00188 
00189     /* Get number of samples available */
00190     alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
00191     if (error = al_get_error(ad->device, &error_msg)) goto fail;
00192 
00193     /* Create a packet of appropriate size */
00194     av_new_packet(pkt, nb_samples*ad->sample_step);
00195     pkt->pts = av_gettime();
00196 
00197     /* Fill the packet with the available samples */
00198     alcCaptureSamples(ad->device, pkt->data, nb_samples);
00199     if (error = al_get_error(ad->device, &error_msg)) goto fail;
00200 
00201     return pkt->size;
00202 fail:
00203     /* Handle failure */
00204     if (pkt->data)
00205         av_destruct_packet(pkt);
00206     if (error_msg)
00207         av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
00208     return error;
00209 }
00210 
00211 static int read_close(AVFormatContext* ctx)
00212 {
00213     al_data *ad = ctx->priv_data;
00214 
00215     if (ad->device) {
00216         alcCaptureStop(ad->device);
00217         alcCaptureCloseDevice(ad->device);
00218     }
00219     return 0;
00220 }
00221 
00222 #define OFFSET(x) offsetof(al_data, x)
00223 
00224 static const AVOption options[] = {
00225     {"channels", "set number of channels",     OFFSET(channels),     AV_OPT_TYPE_INT, {.dbl=2},     1, 2,      AV_OPT_FLAG_DECODING_PARAM },
00226     {"sample_rate", "set sample rate",         OFFSET(sample_rate),  AV_OPT_TYPE_INT, {.dbl=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
00227     {"sample_size", "set sample size",         OFFSET(sample_size),  AV_OPT_TYPE_INT, {.dbl=16},    8, 16,     AV_OPT_FLAG_DECODING_PARAM },
00228     {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.dbl=0},     0, 1,      AV_OPT_FLAG_DECODING_PARAM, "list_devices"  },
00229     {"true",  "", 0, AV_OPT_TYPE_CONST, {.dbl=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
00230     {"false", "", 0, AV_OPT_TYPE_CONST, {.dbl=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
00231     {NULL},
00232 };
00233 
00234 static const AVClass class = {
00235     .class_name = "openal",
00236     .item_name = av_default_item_name,
00237     .option = options,
00238     .version = LIBAVUTIL_VERSION_INT
00239 };
00240 
00241 AVInputFormat ff_openal_demuxer = {
00242     .name = "openal",
00243     .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
00244     .priv_data_size = sizeof(al_data),
00245     .read_probe = NULL,
00246     .read_header = read_header,
00247     .read_packet = read_packet,
00248     .read_close = read_close,
00249     .flags = AVFMT_NOFILE,
00250     .priv_class = &class
00251 };