2 * This file is part of DisOrder.
3 * Copyright (C) 2009, 2013 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 /* Hardware parameters */
109 snd_pcm_hw_params_t
*hwparams
;
110 snd_pcm_hw_params_alloca(&hwparams
);
111 if((err
= snd_pcm_hw_params_any(alsa_pcm
, hwparams
)) < 0)
112 disorder_fatal(0, "error from snd_pcm_hw_params_any: %d", err
);
113 if((err
= snd_pcm_hw_params_set_access(alsa_pcm
, hwparams
,
114 SND_PCM_ACCESS_RW_INTERLEAVED
)) < 0)
115 disorder_fatal(0, "error from snd_pcm_hw_params_set_access: %d", err
);
117 if(uaudio_bits
== 16)
118 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S16
: SND_PCM_FORMAT_U16
;
120 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S8
: SND_PCM_FORMAT_U8
;
121 if((err
= snd_pcm_hw_params_set_format(alsa_pcm
, hwparams
,
123 disorder_fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
125 unsigned rate
= uaudio_rate
;
126 if((err
= snd_pcm_hw_params_set_rate_near(alsa_pcm
, hwparams
, &rate
, 0)) < 0)
127 disorder_fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
129 if((err
= snd_pcm_hw_params_set_channels(alsa_pcm
, hwparams
,
130 uaudio_channels
)) < 0)
131 disorder_fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
132 uaudio_channels
, err
);
133 if((err
= snd_pcm_hw_params(alsa_pcm
, hwparams
)) < 0)
134 disorder_fatal(0, "error calling snd_pcm_hw_params: %d", err
);
135 /* Software parameters */
136 snd_pcm_sw_params_t
*swparams
;
137 snd_pcm_sw_params_alloca(&swparams
);
138 if((err
= snd_pcm_sw_params_current(alsa_pcm
, swparams
)) < 0)
139 disorder_fatal(-err
, "error calling snd_pcm_sw_params_current");
140 /* Bump the start threshold a bit since Pulseaudio sulks with the defaults */
141 if((err
= snd_pcm_sw_params_set_start_threshold(alsa_pcm
, swparams
, 1024)) < 0)
142 disorder_fatal(-err
, "error calling snd_pcm_sw_params_set_start_threshold");
143 if((err
= snd_pcm_sw_params(alsa_pcm
, swparams
)) < 0)
144 disorder_fatal(-err
, "error calling snd_pcm_sw_params");
147 static void alsa_start(uaudio_callback
*callback
,
149 if(uaudio_channels
!= 1 && uaudio_channels
!= 2)
150 disorder_fatal(0, "asked for %d channels but only support 1 or 2",
152 if(uaudio_bits
!= 8 && uaudio_bits
!= 16)
153 disorder_fatal(0, "asked for %d bits/channel but only support 8 or 16",
156 uaudio_thread_start(callback
, userdata
, alsa_play
,
157 32 / uaudio_sample_size
,
158 4096 / uaudio_sample_size
,
162 static void alsa_stop(void) {
163 uaudio_thread_stop();
164 snd_pcm_close(alsa_pcm
);
168 /** @brief Convert a level to a percentage */
169 static int to_percent(long n
) {
170 return (n
- alsa_mixer_min
) * 100 / (alsa_mixer_max
- alsa_mixer_min
);
173 /** @brief Convert a percentage to a level */
174 static int from_percent(int n
) {
175 return alsa_mixer_min
+ n
* (alsa_mixer_max
- alsa_mixer_min
) / 100;
178 static void alsa_open_mixer(void) {
180 snd_mixer_selem_id_t
*id
;
181 const char *device
= uaudio_get("device", "default");
182 const char *mixer
= uaudio_get("mixer-control", "0");
183 const char *channel
= uaudio_get("mixer-channel", "Master");
185 snd_mixer_selem_id_alloca(&id
);
186 if((err
= snd_mixer_open(&alsa_mixer_handle
, 0)))
187 disorder_fatal(0, "snd_mixer_open: %s", snd_strerror(err
));
188 if((err
= snd_mixer_attach(alsa_mixer_handle
, device
)))
189 disorder_fatal(0, "snd_mixer_attach %s: %s", device
, snd_strerror(err
));
190 if((err
= snd_mixer_selem_register(alsa_mixer_handle
,
191 0/*options*/, 0/*classp*/)))
192 disorder_fatal(0, "snd_mixer_selem_register %s: %s",
193 device
, snd_strerror(err
));
194 if((err
= snd_mixer_load(alsa_mixer_handle
)))
195 disorder_fatal(0, "snd_mixer_load %s: %s", device
, snd_strerror(err
));
196 snd_mixer_selem_id_set_name(id
, channel
);
197 snd_mixer_selem_id_set_index(id
, atoi(mixer
));
198 if(!(alsa_mixer_elem
= snd_mixer_find_selem(alsa_mixer_handle
, id
)))
199 disorder_fatal(0, "device '%s' mixer control '%s,%s' does not exist",
200 device
, channel
, mixer
);
201 if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem
))
203 "device '%s' mixer control '%s,%s' has no playback volume",
204 device
, channel
, mixer
);
205 if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem
)) {
206 alsa_mixer_left
= alsa_mixer_right
= SND_MIXER_SCHN_MONO
;
208 alsa_mixer_left
= SND_MIXER_SCHN_FRONT_LEFT
;
209 alsa_mixer_right
= SND_MIXER_SCHN_FRONT_RIGHT
;
211 if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
213 || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
215 disorder_fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
216 device
, channel
, mixer
);
217 snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem
,
218 &alsa_mixer_min
, &alsa_mixer_max
);
222 static void alsa_close_mixer(void) {
223 /* TODO alsa_mixer_elem */
224 if(alsa_mixer_handle
)
225 snd_mixer_close(alsa_mixer_handle
);
228 static void alsa_get_volume(int *left
, int *right
) {
232 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
233 alsa_mixer_left
, &l
))
234 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
235 alsa_mixer_right
, &r
)))
236 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
238 *left
= to_percent(l
);
239 *right
= to_percent(r
);
242 static void alsa_set_volume(int *left
, int *right
) {
247 if(alsa_mixer_left
== alsa_mixer_right
) {
248 /* Mono output - just use the loudest */
249 if((err
= snd_mixer_selem_set_playback_volume
250 (alsa_mixer_elem
, alsa_mixer_left
,
251 from_percent(*left
> *right ?
*left
: *right
))))
252 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
256 if((err
= snd_mixer_selem_set_playback_volume
257 (alsa_mixer_elem
, alsa_mixer_left
, from_percent(*left
)))
258 || (err
= snd_mixer_selem_set_playback_volume
259 (alsa_mixer_elem
, alsa_mixer_right
, from_percent(*right
))))
260 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
263 /* Read it back to see what we ended up at */
264 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
265 alsa_mixer_left
, &l
))
266 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
267 alsa_mixer_right
, &r
)))
268 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
270 *left
= to_percent(l
);
271 *right
= to_percent(r
);
274 static void alsa_configure(void) {
275 uaudio_set("device", config
->device
);
276 uaudio_set("mixer-control", config
->mixer
);
277 uaudio_set("mixer-channel", config
->channel
);
280 const struct uaudio uaudio_alsa
= {
282 .options
= alsa_options
,
285 .activate
= uaudio_thread_activate
,
286 .deactivate
= uaudio_thread_deactivate
,
287 .open_mixer
= alsa_open_mixer
,
288 .close_mixer
= alsa_close_mixer
,
289 .get_volume
= alsa_get_volume
,
290 .set_volume
= alsa_set_volume
,
291 .configure
= alsa_configure
,
292 .flags
= UAUDIO_API_CLIENT
| UAUDIO_API_SERVER
,