static void set_params(void)
{
hwparams.format=SND_PCM_FORMAT_S16_LE;
hwparams.channels=2;
hwparams.rate=44100;
snd_pcm_hw_params_t *params;
snd_pcm_sw_params_t *swparams;
snd_pcm_hw_params_alloca(¶ms);
snd_pcm_sw_params_alloca(&swparams);
snd_pcm_hw_params_any(handle, params);
snd_pcm_hw_params_set_format(handle, params, hwparams.format);
snd_pcm_hw_params_set_channels(handle, params, hwparams.channels);
snd_pcm_hw_params_set_rate_near(handle, params, &hwparams.rate, 0);
buffer_time=0;
snd_pcm_hw_params_get_buffer_time_max(params,&buffer_time, 0);
period_time=125000;
snd_pcm_hw_params_set_period_time_near(handle, params,&period_time, 0);
buffer_time = 500000;
snd_pcm_hw_params_set_buffer_time_near(handle, params, &buffer_time, 0);
/*monotonic = */snd_pcm_hw_params_is_monotonic(params);
/*can_pause = */snd_pcm_hw_params_can_pause(params);
printf("sizeof(params) : %d\n",sizeof(params));
snd_pcm_hw_params(handle, params);
snd_pcm_uframes_t buffer_size;
snd_pcm_hw_params_get_period_size(params, &chunk_size, 0);
size_t n=chunk_size;
snd_pcm_sw_params_set_avail_min(handle, swparams, n);
snd_pcm_uframes_t start_threshold, stop_threshold;
start_threshold=22050;
snd_pcm_sw_params_set_start_threshold(handle, swparams, start_threshold);
stop_threshold=22050;
snd_pcm_sw_params_set_stop_threshold(handle, swparams, stop_threshold);
snd_pcm_format_physical_width(hwparams.format);
}
int
ga_alsa_set_param(struct Xcap_alsa_param *param) {
snd_pcm_hw_params_t *hwparams = NULL;
snd_pcm_sw_params_t *swparams = NULL;
size_t bits_per_sample;
unsigned int rate;
unsigned int buffer_time = 500000; // in the unit of microsecond
unsigned int period_time = 125000; // = buffer_time/4;
int monotonic = 0;
snd_pcm_uframes_t start_threshold, stop_threshold;
int err;
//
snd_pcm_hw_params_alloca(&hwparams);
snd_pcm_sw_params_alloca(&swparams);
if((err = snd_pcm_hw_params_any(param->handle, hwparams)) < 0) {
ga_error("ALSA: set_param - no configurations available\n");
return -1;
}
if((err = snd_pcm_hw_params_set_access(param->handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
ga_error("ALSA: set_param - access type (interleaved) not available\n");
return -1;
}
if((err = snd_pcm_hw_params_set_format(param->handle, hwparams, param->format)) < 0) {
ga_error("ALSA: set_param - unsupported sample format.\n");
return -1;
}
if((err = snd_pcm_hw_params_set_channels(param->handle, hwparams, param->channels)) < 0) {
ga_error("ALSA: set_param - channles count not available\n");
return -1;
}
rate = param->samplerate;
if((err = snd_pcm_hw_params_set_rate_near(param->handle, hwparams, &rate, 0)) < 0) {
ga_error("ALSA: set_param - set rate failed.\n");
return -1;
}
if((double)param->samplerate*1.05 < rate || (double)param->samplerate*0.95 > rate) {
ga_error("ALSA: set_param/warning - inaccurate rate (req=%iHz, got=%iHz)\n", param->samplerate, rate);
}
//
period_time = buffer_time/4;
if((err = snd_pcm_hw_params_set_period_time_near(param->handle, hwparams, &period_time, 0)) < 0) {
ga_error("ALSA: set_param - set period time failed.\n");
return -1;
}
if((err = snd_pcm_hw_params_set_buffer_time_near(param->handle, hwparams, &buffer_time, 0)) < 0) {
ga_error("ALSA: set_param - set buffer time failed.\n");
return -1;
}
//
monotonic = snd_pcm_hw_params_is_monotonic(hwparams);
if((err = snd_pcm_hw_params(param->handle, hwparams)) < 0) {
ga_error("ALSA: set_param - unable to install hw params:");
snd_pcm_hw_params_dump(hwparams, sndlog);
return -1;
}
snd_pcm_hw_params_get_period_size(hwparams, ¶m->chunk_size, 0);
snd_pcm_hw_params_get_buffer_size(hwparams, ¶m->buffer_size);
if(param->chunk_size == param->buffer_size) {
ga_error("ALSA: set_param - cannot use period equal to buffer size (%lu==%lu)\n",
param->chunk_size, param->buffer_size);
return -1;
}
//
snd_pcm_sw_params_current(param->handle, swparams);
err = snd_pcm_sw_params_set_avail_min(param->handle, swparams, param->chunk_size);
// start_delay = 1 for capture
start_threshold = (double) param->samplerate * /*start_delay=*/ 1 / 1000000;
if(start_threshold < 1) start_threshold = 1;
if(start_threshold > param->buffer_size) start_threshold = param->buffer_size;
if((err = snd_pcm_sw_params_set_start_threshold(param->handle, swparams, start_threshold)) < 0) {
ga_error("ALSA: set_param - set start threshold failed.\n");
return -1;
}
// stop_delay = 0
stop_threshold = param->buffer_size;
if((err = snd_pcm_sw_params_set_stop_threshold(param->handle, swparams, stop_threshold)) < 0) {
ga_error("ALSA: set_param - set stop threshold failed.\n");
return -1;
}
//
if(snd_pcm_sw_params(param->handle, swparams) < 0) {
ga_error("ALSA: set_param - unable to install sw params:");
snd_pcm_sw_params_dump(swparams, sndlog);
return -1;
}
bits_per_sample = snd_pcm_format_physical_width(param->format);
if(param->bits_per_sample != bits_per_sample) {
ga_error("ALSA: set_param - BPS/HW configuration mismatched %d != %d)\n",
param->bits_per_sample, bits_per_sample);
}
param->bits_per_frame = param->bits_per_sample * param->channels;
param->chunk_bytes = param->chunk_size * param->bits_per_frame / 8;
return 0;
}
static size_t
set_params(void)
{
snd_pcm_hw_params_t *params;
snd_pcm_sw_params_t *swparams;
snd_pcm_uframes_t buffer_size;
int err;
size_t n;
unsigned int rate;
snd_pcm_uframes_t start_threshold, stop_threshold;
snd_pcm_hw_params_alloca(¶ms);
snd_pcm_sw_params_alloca(&swparams);
err = snd_pcm_hw_params_any(AHandle, params);
if (err < 0) {
fprintf(stderr, "Broken configuration for this PCM: no configurations available");
exit (1);
}
err = snd_pcm_hw_params_set_access(AHandle, params,
SND_PCM_ACCESS_RW_INTERLEAVED);
if (err < 0) {
fprintf(stderr, "Access type not available");
exit(1);
}
err = snd_pcm_hw_params_set_format(AHandle, params, DEFAULT_FORMAT);
if (err < 0) {
fprintf(stderr, "Sample format non available");
exit(1);
}
err = snd_pcm_hw_params_set_channels(AHandle, params, CHANNELS);
if (err < 0) {
fprintf(stderr, "Channels count non available");
exit(1);
}
rate = DEFAULT_SPEED;
hwparams.rate=DEFAULT_SPEED;
hwparams.format=DEFAULT_FORMAT;
hwparams.channels=CHANNELS;
err = snd_pcm_hw_params_set_rate_near(AHandle, params, &hwparams.rate, 0);
assert(err >= 0);
rate = hwparams.rate;
if (buffer_time == 0 && buffer_frames == 0) {
err = snd_pcm_hw_params_get_buffer_time_max(params,
&buffer_time, 0);
assert(err >= 0);
if (buffer_time > 500000)
buffer_time = 500000;
}
if (period_time == 0 && period_frames == 0) {
if (buffer_time > 0)
period_time = buffer_time / 4;
else
period_frames = buffer_frames / 4;
}
if (period_time > 0)
err = snd_pcm_hw_params_set_period_time_near(AHandle, params,
&period_time, 0);
else
err = snd_pcm_hw_params_set_period_size_near(AHandle, params,
&period_frames, 0);
assert(err >= 0);
if (buffer_time > 0) {
err = snd_pcm_hw_params_set_buffer_time_near(AHandle, params,
&buffer_time, 0);
} else {
err = snd_pcm_hw_params_set_buffer_size_near(AHandle, params,
&buffer_frames);
}
assert(err >= 0);
monotonic = snd_pcm_hw_params_is_monotonic(params);
can_pause = snd_pcm_hw_params_can_pause(params);
err = snd_pcm_hw_params(AHandle, params);
if (err < 0) {
fprintf(stderr, "Unable to install hw params:");
snd_pcm_hw_params_dump(params, Log);
exit(1);
}
snd_pcm_hw_params_get_period_size(params, &chunk_size, 0);
snd_pcm_hw_params_get_buffer_size(params, &buffer_size);
if (chunk_size == buffer_size) {
fprintf(stderr, "Can't use period equal to buffer size (%lu == %lu)",
chunk_size, buffer_size);
exit(1);
}
snd_pcm_sw_params_current(AHandle, swparams);
if (avail_min < 0)
n = chunk_size;
else
n = (double) rate * avail_min / 1000000;
err = snd_pcm_sw_params_set_avail_min(AHandle, swparams, n);
/* round up to closest transfer boundary */
n = buffer_size;
if (start_delay <= 0) {
start_threshold = n + (double) rate * start_delay / 1000000;
} else
start_threshold = (double) rate * start_delay / 1000000;
if (start_threshold < 1)
start_threshold = 1;
if (start_threshold > n)
start_threshold = n;
err = snd_pcm_sw_params_set_start_threshold(AHandle, swparams, start_threshold);
assert(err >= 0);
if (stop_delay <= 0)
stop_threshold = buffer_size + (double) rate * stop_delay / 1000000;
else
stop_threshold = (double) rate * stop_delay / 1000000;
err = snd_pcm_sw_params_set_stop_threshold(AHandle, swparams, stop_threshold);
assert(err >= 0);
if (snd_pcm_sw_params(AHandle, swparams) < 0) {
fprintf(stderr, "unable to install sw params:");
snd_pcm_sw_params_dump(swparams, Log);
exit(1);
}
snd_pcm_dump(AHandle, Log);
bits_per_sample = snd_pcm_format_physical_width(DEFAULT_FORMAT);
bits_per_frame = bits_per_sample * hwparams.channels;
chunk_bytes = chunk_size * bits_per_frame / 8;
buffer_frames = buffer_size; /* for position test */
return chunk_bytes;
}
