2 * This file is part of DisOrder
3 * Copyright (C) 2005, 2006, 2007 Richard Kettlewell
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.
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.
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
20 /** @file server/speaker-alsa.c
21 * @brief Support for @ref BACKEND_ALSA */
31 #include <alsa/asoundlib.h>
33 #include "configuration.h"
36 #include "speaker-protocol.h"
39 /** @brief The current PCM handle */
40 static snd_pcm_t *pcm;
42 /** @brief Last seen buffer size */
43 static snd_pcm_uframes_t last_pcm_bufsize;
45 /** @brief ALSA backend initialization */
46 static void alsa_init(void) {
47 info("selected ALSA backend");
50 /** @brief Log ALSA parameters */
51 static void log_params(snd_pcm_hw_params_t *hwparams,
52 snd_pcm_sw_params_t *swparams) {
56 return; /* too verbose */
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);
76 /** @brief ALSA deactivation */
77 static void alsa_deactivate(void) {
81 if((err = snd_pcm_nonblock(pcm, 0)) < 0)
82 fatal(0, "error calling snd_pcm_nonblock: %d", err);
88 device_state = device_closed;
89 D(("released audio device"));
93 /** @brief ALSA backend activation */
94 static void alsa_activate(void) {
95 /* If we need to change format then close the current device. */
96 if(pcm && !formats_equal(&playing->format, &device_format))
98 /* Now if the sound device is open it must have the right format */
100 snd_pcm_hw_params_t *hwparams;
101 snd_pcm_sw_params_t *swparams;
102 snd_pcm_uframes_t pcm_bufsize;
104 int sample_format = 0;
108 if((err = snd_pcm_open(&pcm,
110 SND_PCM_STREAM_PLAYBACK,
111 SND_PCM_NONBLOCK))) {
112 error(0, "error from snd_pcm_open: %d", err);
115 snd_pcm_hw_params_alloca(&hwparams);
116 D(("set up hw params"));
117 if((err = snd_pcm_hw_params_any(pcm, hwparams)) < 0)
118 fatal(0, "error from snd_pcm_hw_params_any: %d", err);
119 if((err = snd_pcm_hw_params_set_access(pcm, hwparams,
120 SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
121 fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
122 switch(playing->format.bits) {
124 sample_format = SND_PCM_FORMAT_S8;
127 switch(playing->format.byte_format) {
128 case AO_FMT_NATIVE: sample_format = SND_PCM_FORMAT_S16; break;
129 case AO_FMT_LITTLE: sample_format = SND_PCM_FORMAT_S16_LE; break;
130 case AO_FMT_BIG: sample_format = SND_PCM_FORMAT_S16_BE; break;
131 error(0, "unrecognized byte format %d", playing->format.byte_format);
136 error(0, "unsupported sample size %d", playing->format.bits);
139 if((err = snd_pcm_hw_params_set_format(pcm, hwparams,
140 sample_format)) < 0) {
141 error(0, "error from snd_pcm_hw_params_set_format (%d): %d",
145 rate = playing->format.rate;
146 if((err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, 0)) < 0) {
147 error(0, "error from snd_pcm_hw_params_set_rate (%d): %d",
148 playing->format.rate, err);
151 if(rate != (unsigned)playing->format.rate)
152 info("want rate %d, got %u", playing->format.rate, rate);
153 if((err = snd_pcm_hw_params_set_channels(pcm, hwparams,
154 playing->format.channels)) < 0) {
155 error(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
156 playing->format.channels, err);
159 pcm_bufsize = 3 * FRAMES;
160 if((err = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams,
162 fatal(0, "error from snd_pcm_hw_params_set_buffer_size (%d): %d",
164 if(pcm_bufsize != 3 * FRAMES && pcm_bufsize != last_pcm_bufsize)
165 info("asked for PCM buffer of %d frames, got %d",
166 3 * FRAMES, (int)pcm_bufsize);
167 last_pcm_bufsize = pcm_bufsize;
168 if((err = snd_pcm_hw_params(pcm, hwparams)) < 0)
169 fatal(0, "error calling snd_pcm_hw_params: %d", err);
170 D(("set up sw params"));
171 snd_pcm_sw_params_alloca(&swparams);
172 if((err = snd_pcm_sw_params_current(pcm, swparams)) < 0)
173 fatal(0, "error calling snd_pcm_sw_params_current: %d", err);
174 if((err = snd_pcm_sw_params_set_avail_min(pcm, swparams, FRAMES)) < 0)
175 fatal(0, "error calling snd_pcm_sw_params_set_avail_min %d: %d",
177 if((err = snd_pcm_sw_params(pcm, swparams)) < 0)
178 fatal(0, "error calling snd_pcm_sw_params: %d", err);
179 device_format = playing->format;
180 D(("acquired audio device"));
181 log_params(hwparams, swparams);
182 device_state = device_open;
188 /* We assume the error is temporary and that we'll retry in a bit. */
192 device_state = device_error;
197 /** @brief Play via ALSA */
198 static size_t alsa_play(size_t frames) {
199 snd_pcm_sframes_t pcm_written_frames;
202 pcm_written_frames = snd_pcm_writei(pcm,
203 playing->buffer + playing->start,
205 D(("actually play %zu frames, wrote %d",
206 frames, (int)pcm_written_frames));
207 if(pcm_written_frames < 0) {
208 switch(pcm_written_frames) {
209 case -EPIPE: /* underrun */
210 error(0, "snd_pcm_writei reports underrun");
211 if((err = snd_pcm_prepare(pcm)) < 0)
212 fatal(0, "error calling snd_pcm_prepare: %d", err);
217 fatal(0, "error calling snd_pcm_writei: %d",
218 (int)pcm_written_frames);
221 return pcm_written_frames;
224 static int alsa_slots, alsa_nslots = -1;
226 /** @brief Fill in poll fd array for ALSA */
227 static void alsa_beforepoll(void) {
228 /* We send sample data to ALSA as fast as it can accept it, relying on
229 * the fact that it has a relatively small buffer to minimize pause
236 alsa_nslots = snd_pcm_poll_descriptors(pcm, &fds[fdno], NFDS - fdno);
238 || !(fds[alsa_slots].events & POLLOUT))
239 && snd_pcm_state(pcm) == SND_PCM_STATE_XRUN) {
240 error(0, "underrun detected after call to snd_pcm_poll_descriptors()");
241 if((err = snd_pcm_prepare(pcm)))
242 fatal(0, "error calling snd_pcm_prepare: %d", err);
245 } while(retry-- > 0);
250 /** @brief Process poll() results for ALSA */
251 static int alsa_ready(void) {
254 unsigned short alsa_revents;
256 if((err = snd_pcm_poll_descriptors_revents(pcm,
260 fatal(0, "error calling snd_pcm_poll_descriptors_revents: %d", err);
261 if(alsa_revents & (POLLOUT | POLLERR))
267 const struct speaker_backend alsa_backend = {