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>
29 #include "configuration.h"
31 /** @brief The current PCM handle */
32 static snd_pcm_t
*alsa_pcm
;
34 static const char *const alsa_options
[] = {
41 /** @brief Mixer handle */
42 snd_mixer_t
*alsa_mixer_handle
;
44 /** @brief Mixer control */
45 static snd_mixer_elem_t
*alsa_mixer_elem
;
47 /** @brief Left channel */
48 static snd_mixer_selem_channel_id_t alsa_mixer_left
;
50 /** @brief Right channel */
51 static snd_mixer_selem_channel_id_t alsa_mixer_right
;
53 /** @brief Minimum level */
54 static long alsa_mixer_min
;
56 /** @brief Maximum level */
57 static long alsa_mixer_max
;
59 /** @brief Actually play sound via ALSA */
60 static size_t alsa_play(void *buffer
, size_t samples
, unsigned flags
) {
61 /* If we're paused we just pretend. We rely on snd_pcm_writei() blocking so
62 * we have to fake up a sleep here. However it doesn't have to be all that
63 * accurate - in particular it's quite acceptable to greatly underestimate
64 * the required wait time. For 'lengthy' waits we do this by the blunt
65 * instrument of halving it. */
66 if(flags
& UAUDIO_PAUSED
) {
69 const uint64_t ns
= ((uint64_t)samples
* 1000000000
70 / (uaudio_rate
* uaudio_channels
));
71 struct timespec ts
[1];
72 ts
->tv_sec
= ns
/ 1000000000;
73 ts
->tv_nsec
= ns
% 1000000000;
74 while(nanosleep(ts
, ts
) < 0 && errno
== EINTR
)
79 /* ALSA wants 'frames', where frame = several concurrently played samples */
80 const snd_pcm_uframes_t frames
= samples
/ uaudio_channels
;
82 snd_pcm_sframes_t rc
= snd_pcm_writei(alsa_pcm
, buffer
, frames
);
86 if((err
= snd_pcm_prepare(alsa_pcm
)))
87 disorder_fatal(0, "error calling snd_pcm_prepare: %d", err
);
92 disorder_fatal(0, "error calling snd_pcm_writei: %d", (int)rc
);
95 return rc
* uaudio_channels
;
98 /** @brief Open the ALSA sound device */
99 static void alsa_open(void) {
100 const char *device
= uaudio_get("device", "default");
103 if((err
= snd_pcm_open(&alsa_pcm
,
105 SND_PCM_STREAM_PLAYBACK
,
107 disorder_fatal(0, "error from snd_pcm_open: %d", err
);
108 snd_pcm_hw_params_t
*hwparams
;
109 snd_pcm_hw_params_alloca(&hwparams
);
110 if((err
= snd_pcm_hw_params_any(alsa_pcm
, hwparams
)) < 0)
111 disorder_fatal(0, "error from snd_pcm_hw_params_any: %d", err
);
112 if((err
= snd_pcm_hw_params_set_access(alsa_pcm
, hwparams
,
113 SND_PCM_ACCESS_RW_INTERLEAVED
)) < 0)
114 disorder_fatal(0, "error from snd_pcm_hw_params_set_access: %d", err
);
116 if(uaudio_bits
== 16)
117 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S16
: SND_PCM_FORMAT_U16
;
119 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S8
: SND_PCM_FORMAT_U8
;
120 if((err
= snd_pcm_hw_params_set_format(alsa_pcm
, hwparams
,
122 disorder_fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
124 unsigned rate
= uaudio_rate
;
125 if((err
= snd_pcm_hw_params_set_rate_near(alsa_pcm
, hwparams
, &rate
, 0)) < 0)
126 disorder_fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
128 if((err
= snd_pcm_hw_params_set_channels(alsa_pcm
, hwparams
,
129 uaudio_channels
)) < 0)
130 disorder_fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
131 uaudio_channels
, err
);
132 if((err
= snd_pcm_hw_params(alsa_pcm
, hwparams
)) < 0)
133 disorder_fatal(0, "error calling snd_pcm_hw_params: %d", err
);
137 static void alsa_start(uaudio_callback
*callback
,
139 if(uaudio_channels
!= 1 && uaudio_channels
!= 2)
140 disorder_fatal(0, "asked for %d channels but only support 1 or 2",
142 if(uaudio_bits
!= 8 && uaudio_bits
!= 16)
143 disorder_fatal(0, "asked for %d bits/channel but only support 8 or 16",
146 uaudio_thread_start(callback
, userdata
, alsa_play
,
147 32 / uaudio_sample_size
,
148 4096 / uaudio_sample_size
,
152 static void alsa_stop(void) {
153 uaudio_thread_stop();
154 snd_pcm_close(alsa_pcm
);
158 /** @brief Convert a level to a percentage */
159 static int to_percent(long n
) {
160 return (n
- alsa_mixer_min
) * 100 / (alsa_mixer_max
- alsa_mixer_min
);
163 /** @brief Convert a percentage to a level */
164 static int from_percent(int n
) {
165 return alsa_mixer_min
+ n
* (alsa_mixer_max
- alsa_mixer_min
) / 100;
168 static void alsa_open_mixer(void) {
170 snd_mixer_selem_id_t
*id
;
171 const char *device
= uaudio_get("device", "default");
172 const char *mixer
= uaudio_get("mixer-control", "0");
173 const char *channel
= uaudio_get("mixer-channel", "PCM");
175 snd_mixer_selem_id_alloca(&id
);
176 if((err
= snd_mixer_open(&alsa_mixer_handle
, 0)))
177 disorder_fatal(0, "snd_mixer_open: %s", snd_strerror(err
));
178 if((err
= snd_mixer_attach(alsa_mixer_handle
, device
)))
179 disorder_fatal(0, "snd_mixer_attach %s: %s", device
, snd_strerror(err
));
180 if((err
= snd_mixer_selem_register(alsa_mixer_handle
,
181 0/*options*/, 0/*classp*/)))
182 disorder_fatal(0, "snd_mixer_selem_register %s: %s",
183 device
, snd_strerror(err
));
184 if((err
= snd_mixer_load(alsa_mixer_handle
)))
185 disorder_fatal(0, "snd_mixer_load %s: %s", device
, snd_strerror(err
));
186 snd_mixer_selem_id_set_name(id
, channel
);
187 snd_mixer_selem_id_set_index(id
, atoi(mixer
));
188 if(!(alsa_mixer_elem
= snd_mixer_find_selem(alsa_mixer_handle
, id
)))
189 disorder_fatal(0, "device '%s' mixer control '%s,%s' does not exist",
190 device
, channel
, mixer
);
191 if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem
))
193 "device '%s' mixer control '%s,%s' has no playback volume",
194 device
, channel
, mixer
);
195 if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem
)) {
196 alsa_mixer_left
= alsa_mixer_right
= SND_MIXER_SCHN_MONO
;
198 alsa_mixer_left
= SND_MIXER_SCHN_FRONT_LEFT
;
199 alsa_mixer_right
= SND_MIXER_SCHN_FRONT_RIGHT
;
201 if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
203 || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
205 disorder_fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
206 device
, channel
, mixer
);
207 snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem
,
208 &alsa_mixer_min
, &alsa_mixer_max
);
212 static void alsa_close_mixer(void) {
213 /* TODO alsa_mixer_elem */
214 if(alsa_mixer_handle
)
215 snd_mixer_close(alsa_mixer_handle
);
218 static void alsa_get_volume(int *left
, int *right
) {
222 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
223 alsa_mixer_left
, &l
))
224 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
225 alsa_mixer_right
, &r
)))
226 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
228 *left
= to_percent(l
);
229 *right
= to_percent(r
);
232 static void alsa_set_volume(int *left
, int *right
) {
237 if(alsa_mixer_left
== alsa_mixer_right
) {
238 /* Mono output - just use the loudest */
239 if((err
= snd_mixer_selem_set_playback_volume
240 (alsa_mixer_elem
, alsa_mixer_left
,
241 from_percent(*left
> *right ?
*left
: *right
))))
242 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
246 if((err
= snd_mixer_selem_set_playback_volume
247 (alsa_mixer_elem
, alsa_mixer_left
, from_percent(*left
)))
248 || (err
= snd_mixer_selem_set_playback_volume
249 (alsa_mixer_elem
, alsa_mixer_right
, from_percent(*right
))))
250 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
253 /* Read it back to see what we ended up at */
254 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
255 alsa_mixer_left
, &l
))
256 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
257 alsa_mixer_right
, &r
)))
258 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
260 *left
= to_percent(l
);
261 *right
= to_percent(r
);
264 static void alsa_configure(void) {
265 uaudio_set("device", config
->device
);
266 uaudio_set("mixer-control", config
->mixer
);
267 uaudio_set("mixer-channel", config
->channel
);
270 const struct uaudio uaudio_alsa
= {
272 .options
= alsa_options
,
275 .activate
= uaudio_thread_activate
,
276 .deactivate
= uaudio_thread_deactivate
,
277 .open_mixer
= alsa_open_mixer
,
278 .close_mixer
= alsa_close_mixer
,
279 .get_volume
= alsa_get_volume
,
280 .set_volume
= alsa_set_volume
,
281 .configure
= alsa_configure