2 * This file is part of DisOrder.
3 * Copyright (C) 2009 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 lib/uaudio-alsa.c
19 * @brief Support for ALSA backend */
22 #if HAVE_ALSA_ASOUNDLIB_H
24 #include <alsa/asoundlib.h>
30 /** @brief The current PCM handle */
31 static snd_pcm_t *alsa_pcm;
33 static const char *const alsa_options[] = {
40 /** @brief Mixer handle */
41 snd_mixer_t *alsa_mixer_handle;
43 /** @brief Mixer control */
44 static snd_mixer_elem_t *alsa_mixer_elem;
46 /** @brief Left channel */
47 static snd_mixer_selem_channel_id_t alsa_mixer_left;
49 /** @brief Right channel */
50 static snd_mixer_selem_channel_id_t alsa_mixer_right;
52 /** @brief Minimum level */
53 static long alsa_mixer_min;
55 /** @brief Maximum level */
56 static long alsa_mixer_max;
58 /** @brief Actually play sound via ALSA */
59 static size_t alsa_play(void *buffer, size_t samples) {
61 /* ALSA wants 'frames', where frame = several concurrently played samples */
62 const snd_pcm_uframes_t frames = samples / uaudio_channels;
64 snd_pcm_sframes_t rc = snd_pcm_writei(alsa_pcm, buffer, frames);
68 if((err = snd_pcm_prepare(alsa_pcm)))
69 fatal(0, "error calling snd_pcm_prepare: %d", err);
74 fatal(0, "error calling snd_pcm_writei: %d", (int)rc);
77 return rc * uaudio_channels;
80 /** @brief Open the ALSA sound device */
81 static void alsa_open(void) {
82 const char *device = uaudio_get("device", "default");
85 if((err = snd_pcm_open(&alsa_pcm,
87 SND_PCM_STREAM_PLAYBACK,
89 fatal(0, "error from snd_pcm_open: %d", err);
90 snd_pcm_hw_params_t *hwparams;
91 snd_pcm_hw_params_alloca(&hwparams);
92 if((err = snd_pcm_hw_params_any(alsa_pcm, hwparams)) < 0)
93 fatal(0, "error from snd_pcm_hw_params_any: %d", err);
94 if((err = snd_pcm_hw_params_set_access(alsa_pcm, hwparams,
95 SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
96 fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
99 sample_format = uaudio_signed ? SND_PCM_FORMAT_S16 : SND_PCM_FORMAT_U16;
101 sample_format = uaudio_signed ? SND_PCM_FORMAT_S8 : SND_PCM_FORMAT_U8;
102 if((err = snd_pcm_hw_params_set_format(alsa_pcm, hwparams,
104 fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
106 unsigned rate = uaudio_rate;
107 if((err = snd_pcm_hw_params_set_rate_near(alsa_pcm, hwparams, &rate, 0)) < 0)
108 fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
110 if((err = snd_pcm_hw_params_set_channels(alsa_pcm, hwparams,
111 uaudio_channels)) < 0)
112 fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
113 uaudio_channels, err);
114 if((err = snd_pcm_hw_params(alsa_pcm, hwparams)) < 0)
115 fatal(0, "error calling snd_pcm_hw_params: %d", err);
119 static void alsa_activate(void) {
120 uaudio_thread_activate();
123 static void alsa_deactivate(void) {
124 uaudio_thread_deactivate();
127 static void alsa_start(uaudio_callback *callback,
129 if(uaudio_channels != 1 && uaudio_channels != 2)
130 fatal(0, "asked for %d channels but only support 1 or 2",
132 if(uaudio_bits != 8 && uaudio_bits != 16)
133 fatal(0, "asked for %d bits/channel but only support 8 or 16",
136 uaudio_thread_start(callback, userdata, alsa_play,
137 32 / uaudio_sample_size,
138 4096 / uaudio_sample_size);
141 static void alsa_stop(void) {
142 uaudio_thread_stop();
143 snd_pcm_close(alsa_pcm);
147 /** @brief Convert a level to a percentage */
148 static int to_percent(long n) {
149 return (n - alsa_mixer_min) * 100 / (alsa_mixer_max - alsa_mixer_min);
152 static void alsa_open_mixer(void) {
154 snd_mixer_selem_id_t *id;
155 const char *device = uaudio_get("device", "default");
156 const char *mixer = uaudio_get("mixer-control", "0");
157 const char *channel = uaudio_get("mixer-channel", "PCM");
159 snd_mixer_selem_id_alloca(&id);
160 if((err = snd_mixer_open(&alsa_mixer_handle, 0)))
161 fatal(0, "snd_mixer_open: %s", snd_strerror(err));
162 if((err = snd_mixer_attach(alsa_mixer_handle, config->device)))
163 fatal(0, "snd_mixer_attach %s: %s", config->device, snd_strerror(err));
164 if((err = snd_mixer_selem_register(alsa_mixer_handle,
165 0/*options*/, 0/*classp*/)))
166 fatal(0, "snd_mixer_selem_register %s: %s",
167 device, snd_strerror(err));
168 if((err = snd_mixer_load(alsa_mixer_handle)))
169 fatal(0, "snd_mixer_load %s: %s", device, snd_strerror(err));
170 snd_mixer_selem_id_set_name(id, channel);
171 snd_mixer_selem_id_set_index(id, atoi(mixer));
172 if(!(alsa_mixer_elem = snd_mixer_find_selem(alsa_mixer_handle, id)))
173 fatal(0, "device '%s' mixer control '%s,%s' does not exist",
174 device, channel, mixer);
175 if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem))
176 fatal(0, "device '%s' mixer control '%s,%s' has no playback volume",
177 device, channel, mixer);
178 if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem)) {
179 alsa_mixer_left = alsa_mixer_right = SND_MIXER_SCHN_MONO;
181 alsa_mixer_left = SND_MIXER_SCHN_FRONT_LEFT;
182 alsa_mixer_right = SND_MIXER_SCHN_FRONT_RIGHT;
184 if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
186 || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
188 fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
189 device, channel, mixer);
190 snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem,
191 &alsa_mixer_min, &alsa_mixer_max);
195 static void alsa_close_mixer(void) {
196 /* TODO alsa_mixer_elem */
197 if(alsa_mixer_handle)
198 snd_mixer_close(alsa_mixer_handle);
201 static void alsa_get_volume(int *left, int *right) {
205 if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
206 alsa_mixer_left, &l))
207 || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
208 alsa_mixer_right, &r)))
209 fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err));
210 *left = to_percent(l);
211 *right = to_percent(r);
214 static void alsa_set_volume(int *left, int *right) {
219 if(alsa_mixer_left == alsa_mixer_right) {
220 /* Mono output - just use the loudest */
221 if((err = snd_mixer_selem_set_playback_volume
222 (alsa_mixer_elem, alsa_mixer_left,
223 from_percent(*left > *right ? *left : *right))))
224 fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err));
227 if((err = snd_mixer_selem_set_playback_volume
228 (alsa_mixer_elem, alsa_mixer_left, from_percent(*left)))
229 || (err = snd_mixer_selem_set_playback_volume
230 (alsa_mixer_elem, alsa_mixer_right, from_percent(*right))))
231 fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err));
233 /* Read it back to see what we ended up at */
234 if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
235 alsa_mixer_left, &l))
236 || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
237 alsa_mixer_right, &r)))
238 fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err));
239 *left = to_percent(l);
240 *right = to_percent(r);
243 const struct uaudio uaudio_alsa = {
245 .options = alsa_options,
248 .activate = alsa_activate,
249 .deactivate = alsa_deactivate,
250 .open_mixer = alsa_open_mixer,
251 .close_mixer = alsa_close_mixer,
252 .get_volume = alsa_get_volume,
253 .set_volume = alsa_set_volume,