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 3 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU 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, see <http://www.gnu.org/licenses/>.
18 /** @file server/speaker-alsa.c
19 * @brief Support for @ref BACKEND_ALSA */
23 #if HAVE_ALSA_ASOUNDLIB_H
27 #include <alsa/asoundlib.h>
29 #include "configuration.h"
32 #include "speaker-protocol.h"
35 /** @brief The current PCM handle */
36 static snd_pcm_t *pcm;
38 /** @brief Last seen buffer size */
39 static snd_pcm_uframes_t last_pcm_bufsize;
41 /** @brief ALSA backend initialization */
42 static void alsa_init(void) {
43 info("selected ALSA backend");
46 /** @brief Log ALSA parameters */
47 static void log_params(snd_pcm_hw_params_t *hwparams,
48 snd_pcm_sw_params_t *swparams) {
51 return; /* too verbose */
56 snd_pcm_sw_params_get_silence_size(swparams, &f);
57 info("sw silence_size=%lu", (unsigned long)f);
58 snd_pcm_sw_params_get_silence_threshold(swparams, &f);
59 info("sw silence_threshold=%lu", (unsigned long)f);
60 #if HAVE_SND_PCM_SW_PARAMS_GET_SLEEP_MIN
64 snd_pcm_sw_params_get_sleep_min(swparams, &u);
65 info("sw sleep_min=%lu", (unsigned long)u);
68 snd_pcm_sw_params_get_start_threshold(swparams, &f);
69 info("sw start_threshold=%lu", (unsigned long)f);
70 snd_pcm_sw_params_get_stop_threshold(swparams, &f);
71 info("sw stop_threshold=%lu", (unsigned long)f);
72 #if HAVE_SND_PCM_SW_PARAMS_GET_XFER_ALIGN
73 snd_pcm_sw_params_get_xfer_align(swparams, &f);
74 info("sw xfer_align=%lu", (unsigned long)f);
79 /** @brief ALSA deactivation */
80 static void alsa_deactivate(void) {
84 if((err = snd_pcm_nonblock(pcm, 0)) < 0)
85 fatal(0, "error calling snd_pcm_nonblock: %d", err);
91 device_state = device_closed;
92 D(("released audio device"));
96 /** @brief ALSA backend activation */
97 static void alsa_activate(void) {
99 snd_pcm_hw_params_t *hwparams;
100 snd_pcm_sw_params_t *swparams;
101 snd_pcm_uframes_t pcm_bufsize;
103 int sample_format = 0;
107 if((err = snd_pcm_open(&pcm,
109 SND_PCM_STREAM_PLAYBACK,
110 SND_PCM_NONBLOCK))) {
111 error(0, "error from snd_pcm_open: %d", err);
114 snd_pcm_hw_params_alloca(&hwparams);
115 D(("set up hw params"));
116 if((err = snd_pcm_hw_params_any(pcm, hwparams)) < 0)
117 fatal(0, "error from snd_pcm_hw_params_any: %d", err);
118 if((err = snd_pcm_hw_params_set_access(pcm, hwparams,
119 SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
120 fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
121 switch(config->sample_format.bits) {
123 sample_format = SND_PCM_FORMAT_S8;
126 switch(config->sample_format.endian) {
127 case ENDIAN_LITTLE: sample_format = SND_PCM_FORMAT_S16_LE; break;
128 case ENDIAN_BIG: sample_format = SND_PCM_FORMAT_S16_BE; break;
130 error(0, "unrecognized byte format %d", config->sample_format.endian);
135 error(0, "unsupported sample size %d", config->sample_format.bits);
138 if((err = snd_pcm_hw_params_set_format(pcm, hwparams,
139 sample_format)) < 0) {
140 error(0, "error from snd_pcm_hw_params_set_format (%d): %d",
144 rate = config->sample_format.rate;
145 if((err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, 0)) < 0) {
146 error(0, "error from snd_pcm_hw_params_set_rate (%d): %d",
147 config->sample_format.rate, err);
150 if(rate != (unsigned)config->sample_format.rate)
151 info("want rate %d, got %u", config->sample_format.rate, rate);
152 if((err = snd_pcm_hw_params_set_channels
153 (pcm, hwparams, config->sample_format.channels)) < 0) {
154 error(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
155 config->sample_format.channels, err);
158 pcm_bufsize = 3 * FRAMES;
159 if((err = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams,
161 fatal(0, "error from snd_pcm_hw_params_set_buffer_size (%d): %d",
163 if(pcm_bufsize != 3 * FRAMES && pcm_bufsize != last_pcm_bufsize)
164 info("asked for PCM buffer of %d frames, got %d",
165 3 * FRAMES, (int)pcm_bufsize);
166 last_pcm_bufsize = pcm_bufsize;
167 if((err = snd_pcm_hw_params(pcm, hwparams)) < 0)
168 fatal(0, "error calling snd_pcm_hw_params: %d", err);
169 D(("set up sw params"));
170 snd_pcm_sw_params_alloca(&swparams);
171 if((err = snd_pcm_sw_params_current(pcm, swparams)) < 0)
172 fatal(0, "error calling snd_pcm_sw_params_current: %d", err);
173 if((err = snd_pcm_sw_params_set_avail_min(pcm, swparams, FRAMES)) < 0)
174 fatal(0, "error calling snd_pcm_sw_params_set_avail_min %d: %d",
176 if((err = snd_pcm_sw_params(pcm, swparams)) < 0)
177 fatal(0, "error calling snd_pcm_sw_params: %d", err);
178 D(("acquired audio device"));
179 log_params(hwparams, swparams);
180 device_state = device_open;
186 /* We assume the error is temporary and that we'll retry in a bit. */
190 device_state = device_error;
195 /** @brief Play via ALSA */
196 static size_t alsa_play(size_t frames) {
197 snd_pcm_sframes_t pcm_written_frames;
200 pcm_written_frames = snd_pcm_writei(pcm,
201 playing->buffer + playing->start,
203 D(("actually play %zu frames, wrote %d",
204 frames, (int)pcm_written_frames));
205 if(pcm_written_frames < 0) {
206 switch(pcm_written_frames) {
207 case -EPIPE: /* underrun */
208 error(0, "snd_pcm_writei reports underrun");
209 if((err = snd_pcm_prepare(pcm)) < 0)
210 fatal(0, "error calling snd_pcm_prepare: %d", err);
215 fatal(0, "error calling snd_pcm_writei: %d",
216 (int)pcm_written_frames);
219 return pcm_written_frames;
222 static int alsa_slots, alsa_nslots = -1;
224 /** @brief Fill in poll fd array for ALSA */
225 static void alsa_beforepoll(int attribute((unused)) *timeoutp) {
226 /* We send sample data to ALSA as fast as it can accept it, relying on
227 * the fact that it has a relatively small buffer to minimize pause
234 alsa_nslots = snd_pcm_poll_descriptors(pcm, &fds[fdno], NFDS - fdno);
236 || !(fds[alsa_slots].events & POLLOUT))
237 && snd_pcm_state(pcm) == SND_PCM_STATE_XRUN) {
238 error(0, "underrun detected after call to snd_pcm_poll_descriptors()");
239 if((err = snd_pcm_prepare(pcm)))
240 fatal(0, "error calling snd_pcm_prepare: %d", err);
243 } while(retry-- > 0);
248 /** @brief Process poll() results for ALSA */
249 static int alsa_ready(void) {
252 unsigned short alsa_revents;
254 if((err = snd_pcm_poll_descriptors_revents(pcm,
258 fatal(0, "error calling snd_pcm_poll_descriptors_revents: %d", err);
259 if(alsa_revents & (POLLOUT | POLLERR))
265 const struct speaker_backend alsa_backend = {