libavdevice/alsa-audio-common.c

   1 /*
   2  * ALSA input and output
   3  * Copyright (c) 2007 Luca Abeni ( lucabe72 email it )
   4  * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr )
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file libavdevice/alsa-audio-common.c
  25  * ALSA input and output: common code
  26  * @author Luca Abeni ( lucabe72 email it )
  27  * @author Benoit Fouet ( benoit fouet free fr )
  28  * @author Nicolas George ( nicolas george normalesup org )
  29  */
  30
  31 #include "libavformat/avformat.h"
  32 #include <alsa/asoundlib.h>
  33
  34 #include "alsa-audio.h"
  35
  36 static av_cold snd_pcm_format_t codec_id_to_pcm_format(int codec_id)
  37 {
  38     switch(codec_id) {
  39         case CODEC_ID_PCM_S16LE: return SND_PCM_FORMAT_S16_LE;
  40         case CODEC_ID_PCM_S16BE: return SND_PCM_FORMAT_S16_BE;
  41         case CODEC_ID_PCM_S8:    return SND_PCM_FORMAT_S8;
  42         default:                 return SND_PCM_FORMAT_UNKNOWN;
  43     }
  44 }
  45
  46 av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
  47                          unsigned int *sample_rate,
  48                          int channels, enum CodecID *codec_id)
  49 {
  50     AlsaData *s = ctx->priv_data;
  51     const char *audio_device;
  52     int res, flags = 0;
  53     snd_pcm_format_t format;
  54     snd_pcm_t *h;
  55     snd_pcm_hw_params_t *hw_params;
  56     snd_pcm_uframes_t buffer_size, period_size;
  57
  58     if (ctx->filename[0] == 0) audio_device = "default";
  59     else                       audio_device = ctx->filename;
  60
  61     if (*codec_id == CODEC_ID_NONE)
  62         *codec_id = DEFAULT_CODEC_ID;
  63     format = codec_id_to_pcm_format(*codec_id);
  64     if (format == SND_PCM_FORMAT_UNKNOWN) {
  65         av_log(ctx, AV_LOG_ERROR, "sample format 0x%04x is not supported\n", *codec_id);
  66         return AVERROR(ENOSYS);
  67     }
  68     s->frame_size = av_get_bits_per_sample(*codec_id) / 8 * channels;
  69
  70     if (ctx->flags & AVFMT_FLAG_NONBLOCK) {
  71         flags = SND_PCM_NONBLOCK;
  72     }
  73     res = snd_pcm_open(&h, audio_device, mode, flags);
  74     if (res < 0) {
  75         av_log(ctx, AV_LOG_ERROR, "cannot open audio device %s (%s)\n",
  76                audio_device, snd_strerror(res));
  77         return AVERROR_IO;
  78     }
  79
  80     res = snd_pcm_hw_params_malloc(&hw_params);
  81     if (res < 0) {
  82         av_log(ctx, AV_LOG_ERROR, "cannot allocate hardware parameter structure (%s)\n",
  83                snd_strerror(res));
  84         goto fail1;
  85     }
  86
  87     res = snd_pcm_hw_params_any(h, hw_params);
  88     if (res < 0) {
  89         av_log(ctx, AV_LOG_ERROR, "cannot initialize hardware parameter structure (%s)\n",
  90                snd_strerror(res));
  91         goto fail;
  92     }
  93
  94     res = snd_pcm_hw_params_set_access(h, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
  95     if (res < 0) {
  96         av_log(ctx, AV_LOG_ERROR, "cannot set access type (%s)\n",
  97                snd_strerror(res));
  98         goto fail;
  99     }
 100
 101     res = snd_pcm_hw_params_set_format(h, hw_params, format);
 102     if (res < 0) {
 103         av_log(ctx, AV_LOG_ERROR, "cannot set sample format 0x%04x %d (%s)\n",
 104                *codec_id, format, snd_strerror(res));
 105         goto fail;
 106     }
 107
 108     res = snd_pcm_hw_params_set_rate_near(h, hw_params, sample_rate, 0);
 109     if (res < 0) {
 110         av_log(ctx, AV_LOG_ERROR, "cannot set sample rate (%s)\n",
 111                snd_strerror(res));
 112         goto fail;
 113     }
 114
 115     res = snd_pcm_hw_params_set_channels(h, hw_params, channels);
 116     if (res < 0) {
 117         av_log(ctx, AV_LOG_ERROR, "cannot set channel count to %d (%s)\n",
 118                channels, snd_strerror(res));
 119         goto fail;
 120     }
 121
 122     snd_pcm_hw_params_get_buffer_size_max(hw_params, &buffer_size);
 123     /* TODO: maybe use ctx->max_picture_buffer somehow */
 124     res = snd_pcm_hw_params_set_buffer_size_near(h, hw_params, &buffer_size);
 125     if (res < 0) {
 126         av_log(ctx, AV_LOG_ERROR, "cannot set ALSA buffer size (%s)\n",
 127                snd_strerror(res));
 128         goto fail;
 129     }
 130
 131     snd_pcm_hw_params_get_period_size_min(hw_params, &period_size, NULL);
 132     res = snd_pcm_hw_params_set_period_size_near(h, hw_params, &period_size, NULL);
 133     if (res < 0) {
 134         av_log(ctx, AV_LOG_ERROR, "cannot set ALSA period size (%s)\n",
 135                snd_strerror(res));
 136         goto fail;
 137     }
 138     s->period_size = period_size;
 139
 140     res = snd_pcm_hw_params(h, hw_params);
 141     if (res < 0) {
 142         av_log(ctx, AV_LOG_ERROR, "cannot set parameters (%s)\n",
 143                snd_strerror(res));
 144         goto fail;
 145     }
 146
 147     snd_pcm_hw_params_free(hw_params);
 148
 149     s->h = h;
 150     return 0;
 151
 152 fail:
 153     snd_pcm_hw_params_free(hw_params);
 154 fail1:
 155     snd_pcm_close(h);
 156     return AVERROR_IO;
 157 }
 158
 159 av_cold int ff_alsa_close(AVFormatContext *s1)
 160 {
 161     AlsaData *s = s1->priv_data;
 162
 163     snd_pcm_close(s->h);
 164     return 0;
 165 }
 166
 167 int ff_alsa_xrun_recover(AVFormatContext *s1, int err)
 168 {
 169     AlsaData *s = s1->priv_data;
 170     snd_pcm_t *handle = s->h;
 171
 172     av_log(s1, AV_LOG_WARNING, "ALSA buffer xrun.\n");
 173     if (err == -EPIPE) {
 174         err = snd_pcm_prepare(handle);
 175         if (err < 0) {
 176             av_log(s1, AV_LOG_ERROR, "cannot recover from underrun (snd_pcm_prepare failed: %s)\n", snd_strerror(err));
 177
 178             return AVERROR_IO;
 179         }
 180     } else if (err == -ESTRPIPE) {
 181         av_log(s1, AV_LOG_ERROR, "-ESTRPIPE... Unsupported!\n");
 182
 183         return -1;
 184     }
 185     return err;
 186 }