herrie/src/audio_output_alsa.c

   1 /*
   2  * Copyright (c) 2006-2011 Ed Schouten <ed@80386.nl>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26 /**
  27  * @file audio_output_alsa.c
  28  * @brief ALSA audio output driver.
  29  */
  30
  31 #include "stdinc.h"
  32
  33 #include <alsa/asoundlib.h>
  34
  35 #include "audio_file.h"
  36 #include "audio_output.h"
  37 #include "config.h"
  38 #include "gui.h"
  39
  40 /**
  41  * @brief Handle to the audio device obtained from ALSA.
  42  */
  43 static snd_pcm_t                *devhnd;
  44 /**
  45  * @brief the amount of channels that is currently used for playback.
  46  */
  47 static unsigned int             channels = 0;
  48 /**
  49  * @brief the sample rate that is currently used for playback.
  50  */
  51 static unsigned int             srate = 0;
  52 #ifdef BUILD_VOLUME
  53 /**
  54  * @brief Handle to the ALSA mixer.
  55  */
  56 static snd_mixer_t *mixhnd = NULL;
  57 /**
  58  * @brief ALSA mixer element for the audio device.
  59  */
  60 static snd_mixer_elem_t *elem;
  61 #endif /* BUILD_VOLUME */
  62
  63 /**
  64  * @brief Alter the audio output parameters of the audio output device.
  65  */
  66 static int
  67 audio_output_apply_hwparams(void)
  68 {
  69         snd_pcm_hw_params_t *devparam;
  70
  71         snd_pcm_hw_params_alloca(&devparam);
  72
  73         /* Acquire the standard parameters */
  74         if (snd_pcm_hw_params_any(devhnd, devparam) != 0)
  75                 return (-1);
  76
  77         /* Set the access method - XXX: mmap */
  78         if (snd_pcm_hw_params_set_access(devhnd, devparam,
  79             SND_PCM_ACCESS_RW_INTERLEAVED) != 0)
  80                 return (-1);
  81
  82         /* Output format */
  83         if (snd_pcm_hw_params_set_format(devhnd, devparam,
  84             SND_PCM_FORMAT_S16) != 0)
  85                 return (-1);
  86         /* Sample rate */
  87         if (snd_pcm_hw_params_set_rate_near(devhnd, devparam, &srate, NULL) != 0)
  88                 return (-1);
  89         /* Channels */
  90         if (snd_pcm_hw_params_set_channels(devhnd, devparam, channels) != 0)
  91                 return (-1);
  92
  93         /* Drain current data and make sure we aren't underrun */
  94         snd_pcm_drain(devhnd);
  95
  96         /* Apply values */
  97         if (snd_pcm_hw_params(devhnd, devparam) != 0)
  98                 return (-1);
  99
 100         return (0);
 101 }
 102
 103 #ifdef BUILD_VOLUME
 104 /**
 105  * @brief Open the ALSA mixer device, making it possible to adjust the
 106  *        volume.
 107  */
 108 static void
 109 audio_output_volume_open(void)
 110 {
 111         snd_mixer_selem_id_t *mixer;
 112
 113         /* Open mixer device */
 114         if (snd_mixer_open(&mixhnd, 0) != 0)
 115                 return;
 116         if (snd_mixer_attach(mixhnd,
 117             config_getopt("audio.output.alsa.device")) != 0)
 118                 goto bad;
 119         if (snd_mixer_selem_register(mixhnd, NULL, NULL) < 0)
 120                 goto bad;
 121         if (snd_mixer_load(mixhnd) < 0)
 122                 goto bad;
 123
 124         /* Obtain mixer element */
 125         snd_mixer_selem_id_alloca(&mixer);
 126         snd_mixer_selem_id_set_name(mixer, config_getopt("audio.output.alsa.mixer"));
 127
 128         elem = snd_mixer_find_selem(mixhnd, mixer);
 129         if (elem != NULL)
 130                 return;
 131 bad:
 132         snd_mixer_close(mixhnd);
 133         mixhnd = NULL;
 134 }
 135 #endif /* BUILD_VOLUME */
 136
 137 int
 138 audio_output_open(void)
 139 {
 140         /* Open the device */
 141         if (snd_pcm_open(&devhnd, config_getopt("audio.output.alsa.device"),
 142             SND_PCM_STREAM_PLAYBACK, 0) != 0)
 143                 goto error;
 144
 145 #ifdef BUILD_VOLUME
 146         audio_output_volume_open();
 147 #endif /* BUILD_VOLUME */
 148
 149         return (0);
 150 error:
 151         g_printerr("%s\n", _("Cannot open the audio device."));
 152         return (-1);
 153 }
 154
 155 int
 156 audio_output_play(struct audio_file *fd)
 157 {
 158         int16_t buf[8192];
 159         snd_pcm_sframes_t ret, len, done = 0;
 160
 161         if ((len = audio_file_read(fd, buf, sizeof buf / sizeof(int16_t))) == 0)
 162                 return (-1);
 163
 164         if (fd->channels != channels || fd->srate != srate) {
 165                 /* Apply the new values */
 166                 channels = fd->channels;
 167                 srate = fd->srate;
 168                 if (audio_output_apply_hwparams() != 0) {
 169                         gui_msgbar_warn(_("Sample rate or amount of channels not supported."));
 170                         /* Invalidate the old settings */
 171                         srate = 0;
 172                         return (-1);
 173                 }
 174         }
 175
 176         /* ALSA measures in sample lengths */
 177         len /= fd->channels;
 178
 179         /* Our complex error handling for snd_pcm_writei() */
 180         while (done < len) {
 181                 ret = snd_pcm_writei(devhnd, buf + (done * fd->channels), len - done);
 182                 if (ret == -EPIPE) {
 183                         /* Buffer underrun. Try again. */
 184                         if (snd_pcm_prepare(devhnd) != 0)
 185                                 return (-1);
 186                         continue;
 187                 } else if (ret <= 0) {
 188                         /* Some other strange error. */
 189                         return (-1);
 190                 }
 191
 192                 done += ret;
 193         }
 194
 195         return (0);
 196 }
 197
 198 void
 199 audio_output_close(void)
 200 {
 201         snd_pcm_close(devhnd);
 202 #ifdef BUILD_VOLUME
 203         if (mixhnd != NULL)
 204                 snd_mixer_close(mixhnd);
 205 #endif /* BUILD_VOLUME */
 206 }
 207
 208 #ifdef BUILD_VOLUME
 209 /**
 210  * @brief Adjust the audio output by a certain percentage and return the
 211  *        new value.
 212  */
 213 static int
 214 audio_output_volume_adjust(int n)
 215 {
 216         int delta;
 217         long min, max;
 218         long right, left;
 219
 220         if (mixhnd == NULL)
 221                 return (-1);
 222
 223         /* Allow other applications to change mixer */
 224         snd_mixer_handle_events(mixhnd);
 225
 226         /* Obtain volume range boundaries */
 227         if (snd_mixer_selem_get_playback_volume_range(elem, &min, &max) != 0)
 228                 return (-1);
 229         if (min >= max)
 230                 return (-1);
 231
 232         /* Convert delta from percent to steps */
 233         delta = (n * (max - min)) / 100;
 234         if (delta == 0)
 235                 delta = n > 0 ? 1 : -1;
 236
 237         /* Obtain current volume */
 238         if (snd_mixer_selem_get_playback_volume(elem,
 239             SND_MIXER_SCHN_FRONT_LEFT, &left) != 0)
 240                 return (-1);
 241         if (snd_mixer_selem_get_playback_volume(elem,
 242             SND_MIXER_SCHN_FRONT_RIGHT, &right) != 0)
 243                 return (-1);
 244
 245         left = left + delta;
 246         left = CLAMP(left, min, max);
 247         right = right + delta;
 248         right = CLAMP(right, min, max);
 249
 250         /* Set new volume */
 251         if (snd_mixer_selem_set_playback_volume(elem,
 252             SND_MIXER_SCHN_FRONT_LEFT, left) != 0)
 253                 return (-1);
 254         if (snd_mixer_selem_set_playback_volume(elem,
 255             SND_MIXER_SCHN_FRONT_RIGHT, right) != 0)
 256                 return (-1);
 257
 258         /* Convert volume back to a percentage */
 259         return (((left + right) / 2 - min) * 100) / (max - min);
 260 }
 261
 262 int
 263 audio_output_volume_up(void)
 264 {
 265         return audio_output_volume_adjust(4);
 266 }
 267
 268 int
 269 audio_output_volume_down(void)
 270 {
 271         return audio_output_volume_adjust(-4);
 272 }
 273 #endif /* BUILD_VOLUME */