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alsa: reverted broken specification (by me) according device latency being not dependent on user buffer size, now framesPerBuffer parameter and suggestedLatency set overall stream latency

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dmitrykos 2010-06-28 21:19:15 +00:00
commit 71e6e5f6a5
1 changed files with 27 additions and 9 deletions
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36
src/hostapi/alsa/pa_linux_alsa.c
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@ -1474,6 +1474,29 @@ static int CalculatePollTimeout( const PaAlsaStream *stream, unsigned long frame
return (int)ceil( 1000 * frames / stream->streamRepresentation.streamInfo.sampleRate );
}
/** Align value in backward direction.
*
* @param v: Value to align.
* @param align: Alignment value.
*/
static unsigned long ALIGN_BWD(unsigned long v, unsigned long align)
{
return ((v - (align ? v % align : 0)));
}
/** Align value in forward direction.
*
* @param v: Value to align.
* @param align: Alignment value.
*/
static unsigned long ALIGN_FWD(unsigned long v, unsigned long align)
{
unsigned long remainder = (align ? (v % align) : 0);
if (remainder == 0)
return v;
return v + (align - remainder);
}
/** Determine size per host buffer.
*
* During this method call, the component's framesPerBuffer attribute gets computed, and the corresponding period size
@ -1484,16 +1507,13 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
unsigned long framesPerUserBuffer, double sampleRate, snd_pcm_hw_params_t* hwParams, int* accurate )
{
PaError result = paNoError;
unsigned long bufferSize = params->suggestedLatency * sampleRate, framesPerHostBuffer;
unsigned long bufferSize = framesPerUserBuffer + params->suggestedLatency * sampleRate, framesPerHostBuffer;
int dir = 0;
PA_DEBUG(( "%s: frames per user-buffer = %lu\n", __FUNCTION__, framesPerUserBuffer ));
PA_DEBUG(( "%s: suggested latency = %f\n", __FUNCTION__, params->suggestedLatency ));
PA_DEBUG(( "%s: suggested latency = %f\n", __FUNCTION__, params->suggestedLatency ));
PA_DEBUG(( "%s: suggested host buffer size = %lu\n", __FUNCTION__, bufferSize ));
#define ALIGN_BWD(v,align) (((v) - ((align) ? (v) % (align) : 0)))
#define ALIGN_FWD(v,align) (((v) + (align - ((align) ? (v) % (align) : 0))))
#define HOST_BUF_ALIGN 16
{
unsigned numPeriods = numPeriods_, maxPeriods = 0;
/* It may be that the device only supports 2 periods for instance */
@ -1502,11 +1522,9 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
assert( maxPeriods > 1 );
numPeriods = PA_MIN( maxPeriods, numPeriods );
framesPerHostBuffer = ALIGN_FWD((bufferSize / numPeriods), HOST_BUF_ALIGN);
/* Align to 16 bytes for faster copying */
framesPerHostBuffer = ALIGN_FWD((bufferSize / numPeriods), 16);
}
#undef ALIGN_BWD
#undef ALIGN_FWD
#undef HOST_BUF_ALIGN
{
snd_pcm_uframes_t min = 0, max = 0;