mdw@git.distorted.org.uk Git - disorder/blob - server/speaker-alsa.c

   1 /*
   2  * This file is part of DisOrder
   3  * Copyright (C) 2005, 2006, 2007 Richard Kettlewell
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  18  * USA
  19  */
  20 /** @file server/speaker-alsa.c
  21  * @brief Support for @ref BACKEND_ALSA */
  22
  23 #include <config.h>
  24
  25 #if HAVE_ALSA_ASOUNDLIB_H
  26
  27 #include "types.h"
  28
  29 #include <unistd.h>
  30 #include <poll.h>
  31 #include <alsa/asoundlib.h>
  32
  33 #include "configuration.h"
  34 #include "syscalls.h"
  35 #include "log.h"
  36 #include "speaker-protocol.h"
  37 #include "speaker.h"
  38
  39 /** @brief The current PCM handle */
  40 static snd_pcm_t *pcm;
  41
  42 /** @brief Last seen buffer size */
  43 static snd_pcm_uframes_t last_pcm_bufsize;
  44
  45 /** @brief ALSA backend initialization */
  46 static void alsa_init(void) {
  47   info("selected ALSA backend");
  48 }
  49
  50 /** @brief Log ALSA parameters */
  51 static void log_params(snd_pcm_hw_params_t *hwparams,
  52                        snd_pcm_sw_params_t *swparams) {
  53   snd_pcm_uframes_t f;
  54   unsigned u;
  55
  56   return;                               /* too verbose */
  57   if(hwparams) {
  58     /* TODO */
  59   }
  60   if(swparams) {
  61     snd_pcm_sw_params_get_silence_size(swparams, &f);
  62     info("sw silence_size=%lu", (unsigned long)f);
  63     snd_pcm_sw_params_get_silence_threshold(swparams, &f);
  64     info("sw silence_threshold=%lu", (unsigned long)f);
  65     snd_pcm_sw_params_get_sleep_min(swparams, &u);
  66     info("sw sleep_min=%lu", (unsigned long)u);
  67     snd_pcm_sw_params_get_start_threshold(swparams, &f);
  68     info("sw start_threshold=%lu", (unsigned long)f);
  69     snd_pcm_sw_params_get_stop_threshold(swparams, &f);
  70     info("sw stop_threshold=%lu", (unsigned long)f);
  71     snd_pcm_sw_params_get_xfer_align(swparams, &f);
  72     info("sw xfer_align=%lu", (unsigned long)f);
  73   }
  74 }
  75
  76 /** @brief ALSA deactivation */
  77 static void alsa_deactivate(void) {
  78   if(pcm) {
  79     int err;
  80
  81     if((err = snd_pcm_nonblock(pcm, 0)) < 0)
  82       fatal(0, "error calling snd_pcm_nonblock: %d", err);
  83     D(("draining pcm"));
  84     snd_pcm_drain(pcm);
  85     D(("closing pcm"));
  86     snd_pcm_close(pcm);
  87     pcm = 0;
  88     device_state = device_closed;
  89     D(("released audio device"));
  90   }
  91 }
  92
  93 /** @brief ALSA backend activation */
  94 static void alsa_activate(void) {
  95   if(!pcm) {
  96     snd_pcm_hw_params_t *hwparams;
  97     snd_pcm_sw_params_t *swparams;
  98     snd_pcm_uframes_t pcm_bufsize;
  99     int err;
 100     int sample_format = 0;
 101     unsigned rate;
 102
 103     D(("snd_pcm_open"));
 104     if((err = snd_pcm_open(&pcm,
 105                            config->device,
 106                            SND_PCM_STREAM_PLAYBACK,
 107                            SND_PCM_NONBLOCK))) {
 108       error(0, "error from snd_pcm_open: %d", err);
 109       goto error;
 110     }
 111     snd_pcm_hw_params_alloca(&hwparams);
 112     D(("set up hw params"));
 113     if((err = snd_pcm_hw_params_any(pcm, hwparams)) < 0)
 114       fatal(0, "error from snd_pcm_hw_params_any: %d", err);
 115     if((err = snd_pcm_hw_params_set_access(pcm, hwparams,
 116                                            SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
 117       fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
 118     switch(config->sample_format.bits) {
 119     case 8:
 120       sample_format = SND_PCM_FORMAT_S8;
 121       break;
 122     case 16:
 123       switch(config->sample_format.endian) {
 124       case ENDIAN_LITTLE: sample_format = SND_PCM_FORMAT_S16_LE; break;
 125       case ENDIAN_BIG: sample_format = SND_PCM_FORMAT_S16_BE; break;
 126       default:
 127         error(0, "unrecognized byte format %d", config->sample_format.endian);
 128         goto fatal;
 129       }
 130       break;
 131     default:
 132       error(0, "unsupported sample size %d", config->sample_format.bits);
 133       goto fatal;
 134     }
 135     if((err = snd_pcm_hw_params_set_format(pcm, hwparams,
 136                                            sample_format)) < 0) {
 137       error(0, "error from snd_pcm_hw_params_set_format (%d): %d",
 138             sample_format, err);
 139       goto fatal;
 140     }
 141     rate = config->sample_format.rate;
 142     if((err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, 0)) < 0) {
 143       error(0, "error from snd_pcm_hw_params_set_rate (%d): %d",
 144             config->sample_format.rate, err);
 145       goto fatal;
 146     }
 147     if(rate != (unsigned)config->sample_format.rate)
 148       info("want rate %d, got %u", config->sample_format.rate, rate);
 149     if((err = snd_pcm_hw_params_set_channels
 150         (pcm, hwparams, config->sample_format.channels)) < 0) {
 151       error(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
 152             config->sample_format.channels, err);
 153       goto fatal;
 154     }
 155     pcm_bufsize = 3 * FRAMES;
 156     if((err = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams,
 157                                                      &pcm_bufsize)) < 0)
 158       fatal(0, "error from snd_pcm_hw_params_set_buffer_size (%d): %d",
 159             3 * FRAMES, err);
 160     if(pcm_bufsize != 3 * FRAMES && pcm_bufsize != last_pcm_bufsize)
 161       info("asked for PCM buffer of %d frames, got %d",
 162            3 * FRAMES, (int)pcm_bufsize);
 163     last_pcm_bufsize = pcm_bufsize;
 164     if((err = snd_pcm_hw_params(pcm, hwparams)) < 0)
 165       fatal(0, "error calling snd_pcm_hw_params: %d", err);
 166     D(("set up sw params"));
 167     snd_pcm_sw_params_alloca(&swparams);
 168     if((err = snd_pcm_sw_params_current(pcm, swparams)) < 0)
 169       fatal(0, "error calling snd_pcm_sw_params_current: %d", err);
 170     if((err = snd_pcm_sw_params_set_avail_min(pcm, swparams, FRAMES)) < 0)
 171       fatal(0, "error calling snd_pcm_sw_params_set_avail_min %d: %d",
 172             FRAMES, err);
 173     if((err = snd_pcm_sw_params(pcm, swparams)) < 0)
 174       fatal(0, "error calling snd_pcm_sw_params: %d", err);
 175     D(("acquired audio device"));
 176     log_params(hwparams, swparams);
 177     device_state = device_open;
 178   }
 179   return;
 180 fatal:
 181   abandon();
 182 error:
 183   /* We assume the error is temporary and that we'll retry in a bit. */
 184   if(pcm) {
 185     snd_pcm_close(pcm);
 186     pcm = 0;
 187     device_state = device_error;
 188   }
 189   return;
 190 }
 191
 192 /** @brief Play via ALSA */
 193 static size_t alsa_play(size_t frames) {
 194   snd_pcm_sframes_t pcm_written_frames;
 195   int err;
 196
 197   pcm_written_frames = snd_pcm_writei(pcm,
 198                                       playing->buffer + playing->start,
 199                                       frames);
 200   D(("actually play %zu frames, wrote %d",
 201      frames, (int)pcm_written_frames));
 202   if(pcm_written_frames < 0) {
 203     switch(pcm_written_frames) {
 204     case -EPIPE:                        /* underrun */
 205       error(0, "snd_pcm_writei reports underrun");
 206       if((err = snd_pcm_prepare(pcm)) < 0)
 207         fatal(0, "error calling snd_pcm_prepare: %d", err);
 208       return 0;
 209     case -EAGAIN:
 210       return 0;
 211     default:
 212       fatal(0, "error calling snd_pcm_writei: %d",
 213             (int)pcm_written_frames);
 214     }
 215   } else
 216     return pcm_written_frames;
 217 }
 218
 219 static int alsa_slots, alsa_nslots = -1;
 220
 221 /** @brief Fill in poll fd array for ALSA */
 222 static void alsa_beforepoll(void) {
 223   /* We send sample data to ALSA as fast as it can accept it, relying on
 224    * the fact that it has a relatively small buffer to minimize pause
 225    * latency. */
 226   int retry = 3, err;
 227
 228   alsa_slots = fdno;
 229   do {
 230     retry = 0;
 231     alsa_nslots = snd_pcm_poll_descriptors(pcm, &fds[fdno], NFDS - fdno);
 232     if((alsa_nslots <= 0
 233         || !(fds[alsa_slots].events & POLLOUT))
 234        && snd_pcm_state(pcm) == SND_PCM_STATE_XRUN) {
 235       error(0, "underrun detected after call to snd_pcm_poll_descriptors()");
 236       if((err = snd_pcm_prepare(pcm)))
 237         fatal(0, "error calling snd_pcm_prepare: %d", err);
 238     } else
 239       break;
 240   } while(retry-- > 0);
 241   if(alsa_nslots >= 0)
 242     fdno += alsa_nslots;
 243 }
 244
 245 /** @brief Process poll() results for ALSA */
 246 static int alsa_ready(void) {
 247   int err;
 248
 249   unsigned short alsa_revents;
 250
 251   if((err = snd_pcm_poll_descriptors_revents(pcm,
 252                                              &fds[alsa_slots],
 253                                              alsa_nslots,
 254                                              &alsa_revents)) < 0)
 255     fatal(0, "error calling snd_pcm_poll_descriptors_revents: %d", err);
 256   if(alsa_revents & (POLLOUT | POLLERR))
 257     return 1;
 258   else
 259     return 0;
 260 }
 261
 262 const struct speaker_backend alsa_backend = {
 263   BACKEND_ALSA,
 264   0,
 265   alsa_init,
 266   alsa_activate,
 267   alsa_play,
 268   alsa_deactivate,
 269   alsa_beforepoll,
 270   alsa_ready
 271 };
 272
 273 #endif
 274
 275 /*
 276 Local Variables:
 277 c-basic-offset:2
 278 comment-column:40
 279 fill-column:79
 280 indent-tabs-mode:nil
 281 End:
 282 */