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alsa:

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- fixed latency setting dependence on user buffer size, now it is completely independent and user is able to set lowest possible/audible latency (approx. 3-4ms)
 - fixed fixed min. latency for non-MMAPed devices, they do behave similar to MMAPed devices now without a limitation
This commit is contained in:
dmitrykos 2010-06-03 20:09:33 +00:00
commit c8414a679e
1 changed files with 68 additions and 165 deletions
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161
src/hostapi/alsa/pa_linux_alsa.c
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@ -1257,6 +1257,10 @@ static PaError PaAlsaStreamComponent_InitialConfigure( PaAlsaStreamComponent *se
/* test if MMAP supported */
self->canMmap = snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ||
snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0;
PA_DEBUG(("%s: device MMAP SND_PCM_ACCESS_MMAP_INTERLEAVED: %s\n", __FUNCTION__, (snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ? "YES" : "NO")));
PA_DEBUG(("%s: device MMAP SND_PCM_ACCESS_MMAP_NONINTERLEAVED: %s\n", __FUNCTION__, (snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0 ? "YES" : "NO")));
if (!self->canMmap)
{
accessMode = SND_PCM_ACCESS_RW_INTERLEAVED;
@ -1271,12 +1275,17 @@ static PaError PaAlsaStreamComponent_InitialConfigure( PaAlsaStreamComponent *se
/* test if MMAP supported */
self->canMmap = snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ||
snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0;
PA_DEBUG(("%s: device MMAP SND_PCM_ACCESS_MMAP_NONINTERLEAVED: %s\n", __FUNCTION__, (snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ? "YES" : "NO")));
PA_DEBUG(("%s: device MMAP SND_PCM_ACCESS_MMAP_INTERLEAVED: %s\n", __FUNCTION__, (snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0 ? "YES" : "NO")));
if (!self->canMmap)
{
accessMode = SND_PCM_ACCESS_RW_NONINTERLEAVED;
alternateAccessMode = SND_PCM_ACCESS_RW_INTERLEAVED;
}
}
PA_DEBUG(("%s: device can MMAP: %s\n", __FUNCTION__, (self->canMmap ? "YES" : "NO")));
/* If requested access mode fails, try alternate mode */
@ -1478,58 +1487,13 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
unsigned long bufferSize = params->suggestedLatency * sampleRate, framesPerHostBuffer;
int dir = 0;
{
snd_pcm_uframes_t tmp;
snd_pcm_hw_params_get_buffer_size_min( hwParams, &tmp );
bufferSize = PA_MAX( bufferSize, tmp );
snd_pcm_hw_params_get_buffer_size_max( hwParams, &tmp );
bufferSize = PA_MIN( bufferSize, tmp );
}
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 host buffer size = %lu\n", __FUNCTION__, bufferSize ));
assert( bufferSize > 0 );
if( framesPerUserBuffer != paFramesPerBufferUnspecified )
{
/* Preferably the host buffer size should be a multiple of the user buffer size */
if( bufferSize > framesPerUserBuffer )
{
snd_pcm_uframes_t remainder = bufferSize % framesPerUserBuffer;
if( remainder > framesPerUserBuffer / 2. )
bufferSize += framesPerUserBuffer - remainder;
else
bufferSize -= remainder;
assert( bufferSize % framesPerUserBuffer == 0 );
}
else if( framesPerUserBuffer % bufferSize != 0 )
{
/* Find a good compromise between user specified latency and buffer size */
if( bufferSize > framesPerUserBuffer * .75 )
{
bufferSize = framesPerUserBuffer;
}
else
{
snd_pcm_uframes_t newSz = framesPerUserBuffer;
while( newSz / 2 >= bufferSize )
{
if( framesPerUserBuffer % (newSz / 2) != 0 )
{
/* No use dividing any further */
break;
}
newSz /= 2;
}
bufferSize = newSz;
}
assert( framesPerUserBuffer % bufferSize == 0 );
}
}
/* Using the base number of periods, we try to approximate the suggested latency (+1 period),
finding a combination of period/buffer size which best fits these constraints */
#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 */
@ -1538,69 +1502,12 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
assert( maxPeriods > 1 );
numPeriods = PA_MIN( maxPeriods, numPeriods );
if( framesPerUserBuffer != paFramesPerBufferUnspecified )
{
/* Try to get a power-of-two of the user buffer size. */
framesPerHostBuffer = framesPerUserBuffer;
if( framesPerHostBuffer < bufferSize )
{
while( bufferSize / framesPerHostBuffer > numPeriods )
{
framesPerHostBuffer *= 2;
}
/* One extra period is preferrable to one less (should be more robust) */
if( bufferSize / framesPerHostBuffer < numPeriods )
{
framesPerHostBuffer /= 2;
}
}
else
{
while( bufferSize / framesPerHostBuffer < numPeriods )
{
if( framesPerUserBuffer % (framesPerHostBuffer / 2) != 0 )
{
/* Can't be divided any further */
break;
}
framesPerHostBuffer /= 2;
}
framesPerHostBuffer = ALIGN_FWD((bufferSize / numPeriods), HOST_BUF_ALIGN);
}
#undef ALIGN_BWD
#undef ALIGN_FWD
#undef HOST_BUF_ALIGN
if( framesPerHostBuffer < framesPerUserBuffer )
{
assert( framesPerUserBuffer % framesPerHostBuffer == 0 );
if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
{
if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer * 2, 0 ) == 0 )
framesPerHostBuffer *= 2;
else if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer / 2, 0 ) == 0 )
framesPerHostBuffer /= 2;
}
}
else
{
assert( framesPerHostBuffer % framesPerUserBuffer == 0 );
if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
{
if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer + framesPerUserBuffer, 0 ) == 0 )
framesPerHostBuffer += framesPerUserBuffer;
else if( snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer - framesPerUserBuffer, 0 ) == 0 )
framesPerHostBuffer -= framesPerUserBuffer;
}
}
}
else
{
framesPerHostBuffer = bufferSize / numPeriods;
}
}
/* non-mmap mode needs a reasonably-sized buffer or it'll stutter */
if( !self->canMmap && framesPerHostBuffer < 2048 )
framesPerHostBuffer = 2048;
assert( framesPerHostBuffer > 0 );
{
snd_pcm_uframes_t min = 0, max = 0;
ENSURE_( snd_pcm_hw_params_get_period_size_min( hwParams, &min, NULL ), paUnanticipatedHostError );
@ -1619,6 +1526,10 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
framesPerHostBuffer = max;
}
PA_DEBUG(( "%s: device period minimum = %lu\n", __FUNCTION__, min ));
PA_DEBUG(( "%s: device period maximum = %lu\n", __FUNCTION__, max ));
PA_DEBUG(( "%s: host buffer period = %lu\n", __FUNCTION__, framesPerHostBuffer ));
assert( framesPerHostBuffer >= min && framesPerHostBuffer <= max );
dir = 0;
ENSURE_( snd_pcm_hw_params_set_period_size_near( self->pcm, hwParams, &framesPerHostBuffer, &dir ),
@ -1629,6 +1540,8 @@ static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamCompo
*accurate = 0;
}
}
/* Set result */
self->framesPerBuffer = framesPerHostBuffer;
error:
@ -2032,9 +1945,6 @@ static PaError CloseStream( PaStream* s )
PaError result = paNoError;
PaAlsaStream *stream = (PaAlsaStream*)s;
free(stream->playback.nonMmapBuffer);
free(stream->capture.nonMmapBuffer);
PaUtil_TerminateBufferProcessor( &stream->bufferProcessor );
PaUtil_TerminateStreamRepresentation( &stream->streamRepresentation );
@ -3115,11 +3025,7 @@ static PaError PaAlsaStreamComponent_RegisterChannels( PaAlsaStreamComponent* se
}
else
{
/* using realloc for optimisation
free( self->nonMmapBuffer );
self->nonMmapBuffer = calloc( self->numHostChannels, snd_pcm_format_size( self->nativeFormat, self->framesPerBuffer + 1 ) );
*/
unsigned int bufferSize = self->numHostChannels * snd_pcm_format_size( self->nativeFormat, self->framesPerBuffer + 1 );
unsigned int bufferSize = self->numHostChannels * snd_pcm_format_size( self->nativeFormat, *numFrames );
if (bufferSize > self->nonMmapBufferSize)
{
self->nonMmapBuffer = realloc(self->nonMmapBuffer, (self->nonMmapBufferSize = bufferSize));
@ -3146,20 +3052,22 @@ static PaError PaAlsaStreamComponent_RegisterChannels( PaAlsaStreamComponent* se
else
{
if( self->canMmap )
{
for( i = 0; i < self->numUserChannels; ++i )
{
area = areas + i;
buffer = ExtractAddress( area, self->offset );
setChannel( bp, i, buffer, 1 );
}
}
else
{
int bufsize = snd_pcm_format_size( self->nativeFormat, self->framesPerBuffer + 1 );
unsigned int buf_per_ch_size = self->nonMmapBufferSize / self->numHostChannels;
buffer = self->nonMmapBuffer;
for( i = 0; i < self->numUserChannels; ++i )
{
setChannel( bp, i, buffer, 1 );
buffer += bufsize;
buffer += buf_per_ch_size;
}
}
}
@ -3173,13 +3081,13 @@ static PaError PaAlsaStreamComponent_RegisterChannels( PaAlsaStreamComponent* se
else
{
void *bufs[self->numHostChannels];
int bufsize = snd_pcm_format_size( self->nativeFormat, self->framesPerBuffer + 1 );
unsigned int buf_per_ch_size = self->nonMmapBufferSize / self->numHostChannels;
unsigned char *buffer = self->nonMmapBuffer;
int i;
for( i = 0; i < self->numHostChannels; ++i )
{
bufs[i] = buffer;
buffer += bufsize;
buffer += buf_per_ch_size;
}
res = snd_pcm_readn( self->pcm, bufs, *numFrames );
}
@ -3187,11 +3095,6 @@ static PaError PaAlsaStreamComponent_RegisterChannels( PaAlsaStreamComponent* se
{
*xrun = 1;
*numFrames = 0;
/* using realloc for optimisation
free( self->nonMmapBuffer );
self->nonMmapBuffer = NULL;
*/
}
}