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Alsa: re-write SetApproximateSampleRate() to allow small deviations from a nominal requested rate, so inexactly clocked cards do not fail (use 1% tolerance).

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This commit is contained in:
gineera 2012-05-18 16:04:30 +00:00
commit f69a02a99a
1 changed files with 27 additions and 26 deletions
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53
src/hostapi/alsa/pa_linux_alsa.c
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@ -87,6 +87,9 @@
/* Combine version elements into a single (unsigned) integer */
#define ALSA_VERSION_INT(major, minor, subminor) ((major << 16) | (minor << 8) | subminor)
/* The acceptable tolerance of sample rate set, to that requested (as a ratio, eg 50 is 2%, 100 is 1%) */
#define RATE_MAX_DEVIATE_RATIO 100
/* Defines Alsa function types and pointers to these functions. */
#define _PA_DEFINE_FUNC(x) typedef typeof(x) x##_ft; static x##_ft *alsa_##x = 0
@ -872,6 +875,7 @@ static PaError GropeDevice( snd_pcm_t* pcm, int isPlug, StreamDirection mode, in
if( SetApproximateSampleRate( pcm, hwParams, defaultSr ) < 0 )
{
defaultSr = -1.;
alsa_snd_pcm_hw_params_any( pcm, hwParams ); /* Clear any params (rate) that might have been set */
PA_DEBUG(( "%s: Original default samplerate failed, trying again ..\n", __FUNCTION__ ));
}
}
@ -926,7 +930,7 @@ static PaError GropeDevice( snd_pcm_t* pcm, int isPlug, StreamDirection mode, in
/* Have to reset hwParams, to set new buffer size; need to also set sample rate again */
ENSURE_( alsa_snd_pcm_hw_params_any( pcm, hwParams ), paUnanticipatedHostError );
ENSURE_( alsa_snd_pcm_hw_params_set_rate( pcm, hwParams, defaultSr, 0 ), paUnanticipatedHostError );
ENSURE_( SetApproximateSampleRate( pcm, hwParams, defaultSr ), paUnanticipatedHostError );
ENSURE_( alsa_snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &highLatency ), paUnanticipatedHostError );
*minChannels = (int)minChans;
@ -1995,13 +1999,18 @@ static PaError PaAlsaStreamComponent_InitialConfigure( PaAlsaStreamComponent *se
/* Some specific hardware (reported: Audio8 DJ) can fail with assertion during this step. */
ENSURE_( alsa_snd_pcm_hw_params_set_format( pcm, hwParams, self->nativeFormat ), paUnanticipatedHostError );
ENSURE_( SetApproximateSampleRate( pcm, hwParams, sr ), paInvalidSampleRate );
ENSURE_( GetExactSampleRate( hwParams, &sr ), paUnanticipatedHostError );
/* reject if there's no sample rate within 1% of the one requested */
if( ( fabs( *sampleRate - sr ) / *sampleRate ) > 0.01 )
if( ( result = SetApproximateSampleRate( pcm, hwParams, sr )) != paUnanticipatedHostError )
{
PA_DEBUG(( "%s: Wanted %f, closest sample rate was %d\n", __FUNCTION__, sampleRate, sr ));
PA_ENSURE( paInvalidSampleRate );
ENSURE_( GetExactSampleRate( hwParams, &sr ), paUnanticipatedHostError );
if( result == paInvalidSampleRate ) /* From the SetApproximateSampleRate() call above */
{ /* The sample rate was returned as 'out of tolerance' of the one requested */
PA_DEBUG(( "%s: Wanted %.3f, closest sample rate was %.3f\n", __FUNCTION__, sampleRate, sr ));
PA_ENSURE( paInvalidSampleRate );
}
}
else
{
PA_ENSURE( paUnanticipatedHostError );
}
ENSURE_( alsa_snd_pcm_hw_params_set_channels( pcm, hwParams, self->numHostChannels ), paInvalidChannelCount );
@ -3138,51 +3147,43 @@ static double GetStreamCpuLoad( PaStream* s )
return PaUtil_GetCpuLoad( &stream->cpuLoadMeasurer );
}
/* Set the stream sample rate to a nominal value requested; allow only a defined tolerance range */
static int SetApproximateSampleRate( snd_pcm_t *pcm, snd_pcm_hw_params_t *hwParams, double sampleRate )
{
PaError result = paNoError;
unsigned long approx = (unsigned long) sampleRate;
int dir = 0;
double fraction = sampleRate - approx;
unsigned int reqRate, setRate, deviation;
assert( pcm && hwParams );
if( fraction > 0.0 )
{
if( fraction > 0.5 )
{
++approx;
dir = -1;
}
else
dir = 1;
}
/* The Alsa sample rate is set by integer value; also the actual rate may differ */
reqRate = setRate = (unsigned int) sampleRate;
if( alsa_snd_pcm_hw_params_set_rate( pcm, hwParams, approx, dir ) < 0 )
ENSURE_( alsa_snd_pcm_hw_params_set_rate_near( pcm, hwParams, &setRate, NULL ), paUnanticipatedHostError );
/* The value actually set will be put in 'setRate' (may be way off); check the deviation as a proportion
* of the requested-rate with reference to the max-deviate-ratio (larger values allow less deviation) */
deviation = abs( setRate - reqRate );
if( deviation > 0 && deviation * RATE_MAX_DEVIATE_RATIO > reqRate )
result = paInvalidSampleRate;
end:
return result;
error:
/* Log */
{
unsigned int _min = 0, _max = 0;
int _dir = 0;
ENSURE_( alsa_snd_pcm_hw_params_get_rate_min( hwParams, &_min, &_dir ), paUnanticipatedHostError );
ENSURE_( alsa_snd_pcm_hw_params_get_rate_max( hwParams, &_max, &_dir ), paUnanticipatedHostError );
PA_DEBUG(( "%s: SR min = %d, max = %d, req = %lu\n", __FUNCTION__, _min, _max, approx ));
PA_DEBUG(( "%s: SR min = %u, max = %u, req = %u\n", __FUNCTION__, _min, _max, reqRate ));
}
goto end;
}
/* Return exact sample rate in param sampleRate */
static int GetExactSampleRate( snd_pcm_hw_params_t *hwParams, double *sampleRate )
{
unsigned int num, den;
unsigned int num, den = 1;
int err;
assert( hwParams );