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audio_alsa.c
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audio_alsa.c
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/*
* libalsa output driver. This file is part of Shairport.
* Copyright (c) Muffinman, Skaman 2013
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#define ALSA_PCM_NEW_HW_PARAMS_API
#include "audio.h"
#include "common.h"
#include <alsa/asoundlib.h>
#include <math.h>
#include <memory.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
static void help(void);
static int init(int argc, char **argv);
static void deinit(void);
static void start(int i_sample_rate, int i_sample_format);
static void play(short buf[], int samples);
static void stop(void);
static void flush(void);
int delay(long *the_delay);
static void volume(double vol);
void do_volume(double vol);
void do_mute(int request);
static void linear_volume(double vol);
static void parameters(audio_parameters *info);
static void mute(int do_mute);
static double set_volume;
static int output_method_signalled = 0;
audio_output audio_alsa = {.name = "alsa",
.help = &help,
.init = &init,
.deinit = &deinit,
.start = &start,
.stop = &stop,
.flush = &flush,
.delay = &delay,
.play = &play,
.mute = NULL, // a function will be provided if it can, and is allowed to, do hardware mute
.volume = NULL, // a function will be provided if it can do hardware volume
.parameters = ¶meters};
static pthread_mutex_t alsa_mutex = PTHREAD_MUTEX_INITIALIZER;
static unsigned int desired_sample_rate;
static enum sps_format_t sample_format;
static snd_pcm_t *alsa_handle = NULL;
static snd_pcm_hw_params_t *alsa_params = NULL;
static snd_ctl_t *ctl = NULL;
static snd_ctl_elem_id_t *elem_id = NULL;
static snd_mixer_t *alsa_mix_handle = NULL;
static snd_mixer_elem_t *alsa_mix_elem = NULL;
static snd_mixer_selem_id_t *alsa_mix_sid = NULL;
static long alsa_mix_minv, alsa_mix_maxv;
static long alsa_mix_mindb, alsa_mix_maxdb;
static char *alsa_out_dev = "default";
static char *alsa_mix_dev = NULL;
static char *alsa_mix_ctrl = "Master";
static int alsa_mix_index = 0;
static int hardware_mixer = 0;
static int has_softvol = 0;
static int volume_set_request = 0; // set when an external request is made to set the volume.
int mute_request_pending = 0; // set when an external request is made to mute or unmute.
int overriding_mute_state_requested = 0; // 1 = mute; 0 = unmute requested
static snd_pcm_sframes_t (*alsa_pcm_write)(snd_pcm_t *, const void *,
snd_pcm_uframes_t) = snd_pcm_writei;
static int play_number;
static int64_t accumulated_delay, accumulated_da_delay;
int alsa_characteristics_already_listed = 0;
static snd_pcm_uframes_t period_size_requested, buffer_size_requested;
static int set_period_size_request, set_buffer_size_request;
static void help(void) {
printf(" -d output-device set the output device [default*|...]\n"
" -m mixer-device set the mixer device ['output-device'*|...]\n"
" -c mixer-control set the mixer control [Master*|...]\n"
" -i mixer-index set the mixer index [0*|...]\n"
" *) default option\n");
}
void set_alsa_out_dev(char *dev) {
alsa_out_dev = dev;
}
int open_mixer() {
if (hardware_mixer) {
debug(2, "Open Mixer");
int ret = 0;
snd_mixer_selem_id_alloca(&alsa_mix_sid);
snd_mixer_selem_id_set_index(alsa_mix_sid, alsa_mix_index);
snd_mixer_selem_id_set_name(alsa_mix_sid, alsa_mix_ctrl);
if ((snd_mixer_open(&alsa_mix_handle, 0)) < 0)
die("Failed to open mixer");
debug(3, "Mixer device name is \"%s\".", alsa_mix_dev);
if ((snd_mixer_attach(alsa_mix_handle, alsa_mix_dev)) < 0)
die("Failed to attach mixer");
if ((snd_mixer_selem_register(alsa_mix_handle, NULL, NULL)) < 0)
die("Failed to register mixer element");
ret = snd_mixer_load(alsa_mix_handle);
if (ret < 0)
die("Failed to load mixer element");
debug(3, "Mixer Control name is \"%s\".", alsa_mix_ctrl);
alsa_mix_elem = snd_mixer_find_selem(alsa_mix_handle, alsa_mix_sid);
if (!alsa_mix_elem)
die("Failed to find mixer element");
return 1;
} else {
return 0;
}
}
void close_mixer() {
if (alsa_mix_handle) {
snd_mixer_close(alsa_mix_handle);
alsa_mix_handle=NULL;
}
}
#define RELEASE_ALSA_MUTEX_AND_DIE(X) pthread_mutex_unlock(&alsa_mutex);die(X);
static int init(int argc, char **argv) {
pthread_mutex_lock(&alsa_mutex);
// debug(2,"audio_alsa init called.");
const char *str;
int value;
double dvalue;
set_period_size_request = 0;
set_buffer_size_request = 0;
config.alsa_use_playback_switch_for_mute = 1;
config.audio_backend_latency_offset = 0;
config.audio_backend_buffer_desired_length = 0.15;
// get settings from settings file first, allow them to be overridden by
// command line options
if (config.cfg != NULL) {
/* Get the desired buffer size setting. */
if (config_lookup_int(config.cfg, "alsa.audio_backend_buffer_desired_length", &value)) {
if ((value < 0) || (value > 66150)) {
inform("The setting alsa.audio_backend_buffer_desired_length is deprecated. "
"Use alsa.audio_backend_buffer_desired_length_in_seconds instead.");
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa audio backend buffer desired length \"%d\". It "
"should be between 0 and "
"66150, default is 6615",
value);
} else {
inform("The setting alsa.audio_backend_buffer_desired_length is deprecated. "
"Use alsa.audio_backend_buffer_desired_length_in_seconds instead.");
config.audio_backend_buffer_desired_length = 1.0 * value / 44100;
}
}
/* Get the desired length of the period of silence before the audio starts. */
if (config_lookup_float(config.cfg, "alsa.audio_backend_silent_lead_in_time",
&dvalue)) {
if ((dvalue < 0.05) || (dvalue > 4)) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa audio_backend_silent_lead_in_time \"%f\". It "
"must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
dvalue);
} else {
config.audio_backend_silent_lead_in_time = dvalue;
}
}
/* Get the desired buffer size setting. */
if (config_lookup_float(config.cfg, "alsa.audio_backend_buffer_desired_length_in_seconds",
&dvalue)) {
if ((dvalue < 0) || (dvalue > 1.5)) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa audio backend buffer desired time \"%f\". It "
"should be between 0 and "
"1.5, default is 0.15 seconds",
dvalue);
} else {
config.audio_backend_buffer_desired_length = dvalue;
}
}
/* Get the latency offset. */
if (config_lookup_int(config.cfg, "alsa.audio_backend_latency_offset", &value)) {
if ((value < -66150) || (value > 66150)) {
inform("The setting alsa.audio_backend_latency_offset is deprecated. "
"Use alsa.audio_backend_latency_offset_in_seconds instead.");
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa audio backend buffer latency offset \"%d\". It "
"should be between -66150 and +66150, default is 0",
value);
} else {
inform("The setting alsa.audio_backend_latency_offset is deprecated. "
"Use alsa.audio_backend_latency_offset_in_seconds instead.");
config.audio_backend_latency_offset = 1.0 * value / 44100;
}
}
/* Get the latency offset. */
if (config_lookup_float(config.cfg, "alsa.audio_backend_latency_offset_in_seconds", &dvalue)) {
if ((dvalue < -1.0) || (dvalue > 1.5)) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa audio backend buffer latency offset time \"%f\". It "
"should be between -1.0 and +1.5, default is 0 seconds",
dvalue);
} else {
config.audio_backend_latency_offset = dvalue;
}
}
/* Get the Output Device Name. */
if (config_lookup_string(config.cfg, "alsa.output_device", &str)) {
alsa_out_dev = (char *)str;
}
/* Get the Mixer Type setting. */
if (config_lookup_string(config.cfg, "alsa.mixer_type", &str)) {
inform("The alsa mixer_type setting is deprecated and has been ignored. "
"FYI, using the \"mixer_control_name\" setting automatically "
"chooses a hardware mixer.");
}
/* Get the Mixer Device Name. */
if (config_lookup_string(config.cfg, "alsa.mixer_device", &str)) {
alsa_mix_dev = (char *)str;
}
/* Get the Mixer Control Name. */
if (config_lookup_string(config.cfg, "alsa.mixer_control_name", &str)) {
alsa_mix_ctrl = (char *)str;
hardware_mixer = 1;
}
/* Get the disable_synchronization setting. */
if (config_lookup_string(config.cfg, "alsa.disable_synchronization", &str)) {
if (strcasecmp(str, "no") == 0)
config.no_sync = 0;
else if (strcasecmp(str, "yes") == 0)
config.no_sync = 1;
else {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid disable_synchronization option choice \"%s\". It should be \"yes\" or \"no\"");
}
}
/* Get the mute_using_playback_switch setting. */
if (config_lookup_string(config.cfg, "alsa.mute_using_playback_switch", &str)) {
if (strcasecmp(str, "no") == 0)
config.alsa_use_playback_switch_for_mute = 0;
else if (strcasecmp(str, "yes") == 0)
config.alsa_use_playback_switch_for_mute = 1;
else {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid mute_use_playback_switch option choice \"%s\". It should be \"yes\" or \"no\"");
}
}
/* Get the output format, using the same names as aplay does*/
if (config_lookup_string(config.cfg, "alsa.output_format", &str)) {
if (strcasecmp(str, "S16") == 0)
config.output_format = SPS_FORMAT_S16;
else if (strcasecmp(str, "S24") == 0)
config.output_format = SPS_FORMAT_S24;
else if (strcasecmp(str, "S24_3LE") == 0)
config.output_format = SPS_FORMAT_S24_3LE;
else if (strcasecmp(str, "S24_3BE") == 0)
config.output_format = SPS_FORMAT_S24_3BE;
else if (strcasecmp(str, "S32") == 0)
config.output_format = SPS_FORMAT_S32;
else if (strcasecmp(str, "U8") == 0)
config.output_format = SPS_FORMAT_U8;
else if (strcasecmp(str, "S8") == 0)
config.output_format = SPS_FORMAT_S8;
else {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid output format \"%s\". It should be \"U8\", \"S8\", \"S16\", \"S24\", "
"\"S24_3LE\", \"S24_3BE\" or "
"\"S32\"",
str);
}
}
/* Get the output rate, which must be a multiple of 44,100*/
if (config_lookup_int(config.cfg, "alsa.output_rate", &value)) {
debug(1, "Value read for output rate is %d.", value);
switch (value) {
case 44100:
case 88200:
case 176400:
case 352800:
config.output_rate = value;
break;
default:
pthread_mutex_unlock(&alsa_mutex);
die("Invalid output rate \"%d\". It should be a multiple of 44,100 up to 352,800", value);
}
}
/* Get the use_mmap_if_available setting. */
if (config_lookup_string(config.cfg, "alsa.use_mmap_if_available", &str)) {
if (strcasecmp(str, "no") == 0)
config.no_mmap = 1;
else if (strcasecmp(str, "yes") == 0)
config.no_mmap = 0;
else {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid use_mmap_if_available option choice \"%s\". It should be \"yes\" or \"no\"");
}
}
/* Get the optional period size value */
if (config_lookup_int(config.cfg, "alsa.period_size", &value)) {
set_period_size_request = 1;
debug(1, "Value read for period size is %d.", value);
if (value < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa period size setting \"%d\". It "
"must be greater than 0.",
value);
} else {
period_size_requested = value;
}
}
/* Get the optional buffer size value */
if (config_lookup_int(config.cfg, "alsa.buffer_size", &value)) {
set_buffer_size_request = 1;
debug(1, "Value read for buffer size is %d.", value);
if (value < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid alsa buffer size setting \"%d\". It "
"must be greater than 0.",
value);
} else {
buffer_size_requested = value;
}
}
}
optind = 1; // optind=0 is equivalent to optind=1 plus special behaviour
argv--; // so we shift the arguments to satisfy getopt()
argc++;
// some platforms apparently require optreset = 1; - which?
int opt;
while ((opt = getopt(argc, argv, "d:t:m:c:i:")) > 0) {
switch (opt) {
case 'd':
alsa_out_dev = optarg;
break;
case 't':
inform("The alsa backend -t option is deprecated and has been ignored. "
"FYI, using the -c option automatically chooses a hardware "
"mixer.");
break;
case 'm':
alsa_mix_dev = optarg;
break;
case 'c':
alsa_mix_ctrl = optarg;
hardware_mixer = 1;
break;
case 'i':
alsa_mix_index = strtol(optarg, NULL, 10);
break;
default:
help();
pthread_mutex_unlock(&alsa_mutex);
die("Invalid audio option -%c specified", opt);
}
}
if (optind < argc) {
pthread_mutex_unlock(&alsa_mutex);
die("Invalid audio argument: %s", argv[optind]);
}
debug(1, "Output device name is \"%s\".", alsa_out_dev);
if (hardware_mixer) {
if (alsa_mix_dev == NULL)
alsa_mix_dev = alsa_out_dev;
// Open mixer
open_mixer();
if (snd_mixer_selem_get_playback_volume_range(alsa_mix_elem, &alsa_mix_minv, &alsa_mix_maxv) <
0)
debug(1, "Can't read mixer's [linear] min and max volumes.");
else {
if (snd_mixer_selem_get_playback_dB_range(alsa_mix_elem, &alsa_mix_mindb, &alsa_mix_maxdb) ==
0) {
audio_alsa.volume = &volume; // insert the volume function now we know it can do dB stuff
audio_alsa.parameters = ¶meters; // likewise the parameters stuff
if (alsa_mix_mindb == SND_CTL_TLV_DB_GAIN_MUTE) {
// Raspberry Pi does this
debug(1, "Lowest dB value is a mute -- try minimum volume +1");
if (snd_mixer_selem_ask_playback_vol_dB(alsa_mix_elem, alsa_mix_minv + 1,
&alsa_mix_mindb) != 0)
debug(1, "Can't get dB value corresponding to a minimum volume + 1.");
}
debug(1, "Hardware mixer has dB volume from %f to %f.", (1.0 * alsa_mix_mindb) / 100.0,
(1.0 * alsa_mix_maxdb) / 100.0);
} else {
// use the linear scale and do the db conversion ourselves
debug(1, "note: the hardware mixer specified -- \"%s\" -- does not have "
"a dB volume scale, so it can't be used. Trying software "
"volume control.",
alsa_mix_ctrl);
if (snd_ctl_open(&ctl, alsa_mix_dev, 0) < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("Cannot open control \"%s\"", alsa_mix_dev);
}
if (snd_ctl_elem_id_malloc(&elem_id) < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("Cannot allocate memory for control \"%s\"", alsa_mix_dev);
}
snd_ctl_elem_id_set_interface(elem_id, SND_CTL_ELEM_IFACE_MIXER);
snd_ctl_elem_id_set_name(elem_id, alsa_mix_ctrl);
if (snd_ctl_get_dB_range(ctl, elem_id, &alsa_mix_mindb, &alsa_mix_maxdb) == 0) {
debug(1, "Volume control \"%s\" has dB volume from %f to %f.", alsa_mix_ctrl,
(1.0 * alsa_mix_mindb) / 100.0, (1.0 * alsa_mix_maxdb) / 100.0);
has_softvol = 1;
} else {
debug(1, "Cannot get the dB range from the volume control \"%s\"", alsa_mix_ctrl);
}
/*
debug(1, "Min and max volumes are %d and
%d.",alsa_mix_minv,alsa_mix_maxv);
alsa_mix_maxdb = 0;
if ((alsa_mix_maxv!=0) && (alsa_mix_minv!=0))
alsa_mix_mindb =
-20*100*(log10(alsa_mix_maxv*1.0)-log10(alsa_mix_minv*1.0));
else if (alsa_mix_maxv!=0)
alsa_mix_mindb = -20*100*log10(alsa_mix_maxv*1.0);
audio_alsa.volume = &linear_volume; // insert the linear volume function
audio_alsa.parameters = ¶meters; // likewise the parameters stuff
debug(1,"Max and min dB calculated are %d and
%d.",alsa_mix_maxdb,alsa_mix_mindb);
*/
}
}
if ((config.alsa_use_playback_switch_for_mute==1) && (snd_mixer_selem_has_playback_switch(alsa_mix_elem))) {
audio_alsa.mute = &mute; // insert the mute function now we know it can do muting stuff
// debug(1, "Has mixer and mute ability we will use.");
} else {
// debug(1, "Has mixer but not using hardware mute.");
}
close_mixer();
} else {
// debug(1, "Has no mixer and thus no hardware mute.");
}
alsa_mix_handle = NULL;
pthread_mutex_unlock(&alsa_mutex);
return 0;
}
static void deinit(void) {
// debug(2,"audio_alsa deinit called.");
stop();
}
int open_alsa_device(void) {
//the alsa mutex is already acquired when this is called
const snd_pcm_uframes_t minimal_buffer_headroom =
352 * 2; // we accept this much headroom in the hardware buffer, but we'll
// accept less
const snd_pcm_uframes_t requested_buffer_headroom =
minimal_buffer_headroom + 2048; // we ask for this much headroom in the
// hardware buffer, but we'll accept less
int ret, dir = 0;
unsigned int my_sample_rate = desired_sample_rate;
// snd_pcm_uframes_t frames = 441 * 10;
snd_pcm_uframes_t buffer_size, actual_buffer_length;
snd_pcm_access_t access;
// ensure no calls are made to the alsa device enquiring about the buffer length if
// synchronisation is disabled.
if (config.no_sync != 0)
audio_alsa.delay = NULL;
// ensure no calls are made to the alsa device enquiring about the buffer length if
// synchronisation is disabled.
if (config.no_sync != 0)
audio_alsa.delay = NULL;
ret = snd_pcm_open(&alsa_handle, alsa_out_dev, SND_PCM_STREAM_PLAYBACK, 0);
if (ret < 0)
return (ret);
snd_pcm_hw_params_alloca(&alsa_params);
ret = snd_pcm_hw_params_any(alsa_handle, alsa_params);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);;
die("audio_alsa: Broken configuration for device \"%s\": no configurations "
"available",
alsa_out_dev);
}
if ((config.no_mmap == 0) &&
(snd_pcm_hw_params_set_access(alsa_handle, alsa_params, SND_PCM_ACCESS_MMAP_INTERLEAVED) >=
0)) {
if (output_method_signalled == 0) {
debug(1, "Output written using MMAP");
output_method_signalled = 1;
}
access = SND_PCM_ACCESS_MMAP_INTERLEAVED;
alsa_pcm_write = snd_pcm_mmap_writei;
} else {
if (output_method_signalled == 0) {
debug(1, "Output written with RW");
output_method_signalled = 1;
}
access = SND_PCM_ACCESS_RW_INTERLEAVED;
alsa_pcm_write = snd_pcm_writei;
}
ret = snd_pcm_hw_params_set_access(alsa_handle, alsa_params, access);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: Access type not available for device \"%s\": %s", alsa_out_dev,
snd_strerror(ret));
}
snd_pcm_format_t sf;
switch (sample_format) {
case SPS_FORMAT_S8:
sf = SND_PCM_FORMAT_S8;
break;
case SPS_FORMAT_U8:
sf = SND_PCM_FORMAT_U8;
break;
case SPS_FORMAT_S16:
sf = SND_PCM_FORMAT_S16;
break;
case SPS_FORMAT_S24:
sf = SND_PCM_FORMAT_S24;
break;
case SPS_FORMAT_S24_3LE:
sf = SND_PCM_FORMAT_S24_3LE;
break;
case SPS_FORMAT_S24_3BE:
sf = SND_PCM_FORMAT_S24_3BE;
break;
case SPS_FORMAT_S32:
sf = SND_PCM_FORMAT_S32;
break;
default:
pthread_mutex_unlock(&alsa_mutex);
die("Unsupported output format at audio_alsa.c");
}
ret = snd_pcm_hw_params_set_format(alsa_handle, alsa_params, sf);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: Sample format %d not available for device \"%s\": %s", sample_format, alsa_out_dev,
snd_strerror(ret));
}
ret = snd_pcm_hw_params_set_channels(alsa_handle, alsa_params, 2);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: Channels count (2) not available for device \"%s\": %s", alsa_out_dev,
snd_strerror(ret));
}
ret = snd_pcm_hw_params_set_rate_near(alsa_handle, alsa_params, &my_sample_rate, &dir);
if (ret < 0) {
die("audio_alsa: Rate %iHz not available for playback: %s", desired_sample_rate,
snd_strerror(ret));
}
if (set_period_size_request != 0) {
debug(1, "Attempting to set the period size");
ret = snd_pcm_hw_params_set_period_size_near(alsa_handle, alsa_params, &period_size_requested,
&dir);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: cannot set period size of %lu: %s", period_size_requested,
snd_strerror(ret));
snd_pcm_uframes_t actual_period_size;
snd_pcm_hw_params_get_period_size(alsa_params, &actual_period_size, &dir);
if (actual_period_size != period_size_requested)
inform("Actual period size set to a different value than requested. Requested: %lu, actual "
"setting: %lu",
period_size_requested, actual_period_size);
}
}
if (set_buffer_size_request != 0) {
debug(1, "Attempting to set the buffer size to %lu", buffer_size_requested);
ret = snd_pcm_hw_params_set_buffer_size_near(alsa_handle, alsa_params, &buffer_size_requested);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: cannot set buffer size of %lu: %s", buffer_size_requested,
snd_strerror(ret));
snd_pcm_uframes_t actual_buffer_size;
snd_pcm_hw_params_get_buffer_size(alsa_params, &actual_buffer_size);
if (actual_buffer_size != buffer_size_requested)
inform("Actual period size set to a different value than requested. Requested: %lu, actual "
"setting: %lu",
buffer_size, actual_buffer_size);
}
}
ret = snd_pcm_hw_params(alsa_handle, alsa_params);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: Unable to set hw parameters for device \"%s\": %s.", alsa_out_dev,
snd_strerror(ret));
}
if (my_sample_rate != desired_sample_rate) {
pthread_mutex_unlock(&alsa_mutex);
die("Can't set the D/A converter to %d.", desired_sample_rate);
}
ret = snd_pcm_hw_params_get_buffer_size(alsa_params, &actual_buffer_length);
if (ret < 0) {
pthread_mutex_unlock(&alsa_mutex);
die("audio_alsa: Unable to get hw buffer length for device \"%s\": %s.", alsa_out_dev,
snd_strerror(ret));
}
if (actual_buffer_length < config.audio_backend_buffer_desired_length + minimal_buffer_headroom) {
/*
// the dac buffer is too small, so let's try to set it
buffer_size =
config.audio_backend_buffer_desired_length + requested_buffer_headroom;
ret = snd_pcm_hw_params_set_buffer_size_near(alsa_handle, alsa_params,
&buffer_size);
if (ret < 0)
die("audio_alsa: Unable to set hw buffer size to %lu for device \"%s\": "
"%s.",
config.audio_backend_buffer_desired_length +
requested_buffer_headroom,
alsa_out_dev, snd_strerror(ret));
if (config.audio_backend_buffer_desired_length + minimal_buffer_headroom >
buffer_size) {
die("audio_alsa: Can't set hw buffer size to %lu or more for device "
"\"%s\". Requested size: %lu, granted size: %lu.",
config.audio_backend_buffer_desired_length + minimal_buffer_headroom,
alsa_out_dev, config.audio_backend_buffer_desired_length +
requested_buffer_headroom,
buffer_size);
}
*/
debug(1, "The alsa buffer is smaller (%lu bytes) than the desired backend buffer "
"length (%ld) you have chosen.",
actual_buffer_length, config.audio_backend_buffer_desired_length);
}
if (alsa_characteristics_already_listed == 0) {
alsa_characteristics_already_listed = 1;
int log_level = 2; // the level at which debug information should be output
int rc;
snd_pcm_access_t access_type;
snd_pcm_format_t format_type;
snd_pcm_subformat_t subformat_type;
unsigned int val, val2;
unsigned int uval, uval2;
int sval;
int dir;
snd_pcm_uframes_t frames;
debug(log_level, "PCM handle name = '%s'", snd_pcm_name(alsa_handle));
// ret = snd_pcm_hw_params_any(alsa_handle, alsa_params);
// if (ret < 0) {
// die("audio_alsa: Cannpot get configuration for device \"%s\": no
// configurations
//"
// "available",
// alsa_out_dev);
// }
debug(log_level, "alsa device parameters:");
snd_pcm_hw_params_get_access(alsa_params, &access_type);
debug(log_level, " access type = %s", snd_pcm_access_name(access_type));
snd_pcm_hw_params_get_format(alsa_params, &format_type);
debug(log_level, " format = '%s' (%s)", snd_pcm_format_name(format_type),
snd_pcm_format_description(format_type));
snd_pcm_hw_params_get_subformat(alsa_params, &subformat_type);
debug(log_level, " subformat = '%s' (%s)", snd_pcm_subformat_name(subformat_type),
snd_pcm_subformat_description(subformat_type));
snd_pcm_hw_params_get_channels(alsa_params, &uval);
debug(log_level, " number of channels = %u", uval);
sval = snd_pcm_hw_params_get_sbits(alsa_params);
debug(log_level, " number of significant bits = %d", sval);
snd_pcm_hw_params_get_rate(alsa_params, &uval, &dir);
switch (dir) {
case -1:
debug(log_level, " rate = %u frames per second (<).", uval);
break;
case 0:
debug(log_level, " rate = %u frames per second (precisely).", uval);
break;
case 1:
debug(log_level, " rate = %u frames per second (>).", uval);
break;
}
if (snd_pcm_hw_params_get_rate_numden(alsa_params, &uval, &uval2) == 0)
debug(log_level, " precise (rational) rate = %.3f frames per second (i.e. %u/%u).", uval,
uval2, ((double)uval) / uval2);
else
debug(log_level, " precise (rational) rate information unavailable.");
snd_pcm_hw_params_get_period_time(alsa_params, &uval, &dir);
switch (dir) {
case -1:
debug(log_level, " period_time = %u us (<).", uval);
break;
case 0:
debug(log_level, " period_time = %u us (precisely).", uval);
break;
case 1:
debug(log_level, " period_time = %u us (>).", uval);
break;
}
snd_pcm_hw_params_get_period_size(alsa_params, &frames, &dir);
switch (dir) {
case -1:
debug(log_level, " period_size = %lu frames (<).", frames);
break;
case 0:
debug(log_level, " period_size = %lu frames (precisely).", frames);
break;
case 1:
debug(log_level, " period_size = %lu frames (>).", frames);
break;
}
snd_pcm_hw_params_get_buffer_time(alsa_params, &uval, &dir);
switch (dir) {
case -1:
debug(log_level, " buffer_time = %u us (<).", uval);
break;
case 0:
debug(log_level, " buffer_time = %u us (precisely).", uval);
break;
case 1:
debug(log_level, " buffer_time = %u us (>).", uval);
break;
}
snd_pcm_hw_params_get_buffer_size(alsa_params, &frames);
switch (dir) {
case -1:
debug(log_level, " buffer_size = %lu frames (<).", frames);
break;
case 0:
debug(log_level, " buffer_size = %lu frames (precisely).", frames);
break;
case 1:
debug(log_level, " buffer_size = %lu frames (>).", frames);
break;
}
snd_pcm_hw_params_get_periods(alsa_params, &uval, &dir);
switch (dir) {
case -1:
debug(log_level, " periods_per_buffer = %u (<).", uval);
break;
case 0:
debug(log_level, " periods_per_buffer = %u (precisely).", uval);
break;
case 1:
debug(log_level, " periods_per_buffer = %u (>).", uval);
break;
}
}
return (0);
}
static void start(int i_sample_rate, int i_sample_format) {
// debug(2,"audio_alsa start called.");
if (i_sample_rate == 0)
desired_sample_rate = 44100; // default
else
desired_sample_rate = i_sample_rate; // must be a variable
if (i_sample_format == 0)
sample_format = SPS_FORMAT_S16; // default
else
sample_format = i_sample_format;
}
int delay(long *the_delay) {
// snd_pcm_sframes_t is a signed long -- hence the return of a "long"
int reply;
// debug(3,"audio_alsa delay called.");
if (alsa_handle == NULL) {
return -ENODEV;
} else {
pthread_mutex_lock(&alsa_mutex);
int derr, ignore;
if (snd_pcm_state(alsa_handle) == SND_PCM_STATE_RUNNING) {
*the_delay = 0; // just to see what happens
reply = snd_pcm_delay(alsa_handle, the_delay);
if (reply != 0) {
debug(1, "Error %d in delay(): \"%s\". Delay reported is %d frames.", reply,
snd_strerror(reply), *the_delay);
ignore = snd_pcm_recover(alsa_handle, reply, 1);
}
} else if (snd_pcm_state(alsa_handle) == SND_PCM_STATE_PREPARED) {
*the_delay = 0;
reply = 0; // no error
} else {
if (snd_pcm_state(alsa_handle) == SND_PCM_STATE_XRUN) {
*the_delay = 0;
reply = 0; // no error
} else {
reply = -EIO;
debug(1, "Error -- ALSA delay(): bad state: %d.", snd_pcm_state(alsa_handle));
}
if ((derr = snd_pcm_prepare(alsa_handle))) {
ignore = snd_pcm_recover(alsa_handle, derr, 1);
debug(1, "Error preparing after delay error: \"%s\".", snd_strerror(derr));
}
}
pthread_mutex_unlock(&alsa_mutex);
// here, occasionally pretend there's a problem with pcm_get_delay()
// if ((random() % 100000) < 3) // keep it pretty rare
// reply = -EPERM; // pretend something bad has happened
return reply;
}
}
static void play(short buf[], int samples) {
// debug(3,"audio_alsa play called.");
int ret = 0;
if (alsa_handle == NULL) {
pthread_mutex_lock(&alsa_mutex);
ret = open_alsa_device();
if (ret == 0) {
if (audio_alsa.volume)
do_volume(set_volume);
if (audio_alsa.mute)
do_mute(0);
}
pthread_mutex_unlock(&alsa_mutex);
}
if (ret == 0) {
pthread_mutex_lock(&alsa_mutex);
snd_pcm_sframes_t current_delay = 0;
int err, ignore;
if (snd_pcm_state(alsa_handle) == SND_PCM_STATE_XRUN) {
if ((err = snd_pcm_prepare(alsa_handle))) {
ignore = snd_pcm_recover(alsa_handle, err, 1);
debug(1, "Error preparing after underrun: \"%s\".", snd_strerror(err));
}
}
if ((snd_pcm_state(alsa_handle) == SND_PCM_STATE_PREPARED) ||
(snd_pcm_state(alsa_handle) == SND_PCM_STATE_RUNNING)) {
if (buf == NULL)
debug(1, "NULL buffer passed to pcm_writei -- skipping it");
if (samples == 0)
debug(1, "empty buffer being passed to pcm_writei -- skipping it");
if ((samples != 0) && (buf != NULL)) {
err = alsa_pcm_write(alsa_handle, (char *)buf, samples);
if (err < 0) {
debug(1, "Error %d writing %d samples in play(): \"%s\".", err, samples,
snd_strerror(err));
ignore = snd_pcm_recover(alsa_handle, err, 1);
}
}
} else {
debug(1, "Error -- ALSA device in incorrect state (%d) for play.",
snd_pcm_state(alsa_handle));
if ((err = snd_pcm_prepare(alsa_handle))) {
ignore = snd_pcm_recover(alsa_handle, err, 1);
debug(1, "Error preparing after play error: \"%s\".", snd_strerror(err));
}
}
pthread_mutex_unlock(&alsa_mutex);
}
}
static void flush(void) {
// debug(2,"audio_alsa flush called.");
pthread_mutex_lock(&alsa_mutex);
int derr;
do_mute(1);
if (alsa_handle) {
// debug(1,"Dropping frames for flush...");
/*
if ((derr = snd_pcm_drop(alsa_handle)))
debug(1, "Error dropping frames: \"%s\".", snd_strerror(derr));
// debug(1,"Dropped frames ok. State is %d.",snd_pcm_state(alsa_handle));
if ((derr = snd_pcm_prepare(alsa_handle)))
debug(1, "Error preparing after flush: \"%s\".", snd_strerror(derr));
// debug(1,"Frames successfully dropped.");
*/
/*
if (snd_pcm_state(alsa_handle)==SND_PCM_STATE_PREPARED)
debug(1,"Flush returns to SND_PCM_STATE_PREPARED state.");
if (snd_pcm_state(alsa_handle)==SND_PCM_STATE_RUNNING)
debug(1,"Flush returns to SND_PCM_STATE_RUNNING state.");
*/
/*
if (!((snd_pcm_state(alsa_handle) == SND_PCM_STATE_PREPARED) ||
(snd_pcm_state(alsa_handle) == SND_PCM_STATE_RUNNING)))
debug(1, "Flush returning unexpected state -- %d.", snd_pcm_state(alsa_handle));
*/
// this is derived from https://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2latency_8c-example.html#a45
if ((derr=snd_pcm_nonblock(alsa_handle, 0)))
debug(1, "Error %d (\"%s\") unblocking output device.", derr, snd_strerror(derr));
if ((derr=snd_pcm_drain(alsa_handle)))
debug(1, "Error %d (\"%s\") draining output device.", derr, snd_strerror(derr));
if ((derr=snd_pcm_nonblock(alsa_handle, 1)))
debug(1, "Error %d (\"%s\") reblocking output device.", derr, snd_strerror(derr));
if ((derr=snd_pcm_hw_free(alsa_handle)))
debug(1, "Error %d (\"%s\") freeing output device hardware.", derr, snd_strerror(derr));
// flush also closes the device
snd_pcm_close(alsa_handle);
alsa_handle = NULL;
}
pthread_mutex_unlock(&alsa_mutex);
}
static void stop(void) {
// debug(2,"audio_alsa stop called.");
// when we want to stop, we want the alsa device
// to be closed immediately -- we may even be killing the thread, so we
// don't wish to wait
// so we should flush first
flush(); // flush will also close the device
// close_alsa_device();
}
static void parameters(audio_parameters *info) {
info->minimum_volume_dB = alsa_mix_mindb;
info->maximum_volume_dB = alsa_mix_maxdb;
}
void do_volume(double vol) { // caller is assumed to have the alsa_mutex when using this function
debug(3, "Setting volume db to %f.", vol);
set_volume = vol;
if (volume_set_request && open_mixer()) {
if (has_softvol) {
if (ctl && elem_id) {
snd_ctl_elem_value_t *value;