void SndBuffer::_WriteSamples(StereoOut32 *bData, int nSamples)
{
m_predictData = 0;
// Problem:
// If the SPU2 gets out of sync with the SndOut device, the writepos of the
// circular buffer will overtake the readpos, leading to a prolonged period
// of hopscotching read/write accesses (ie, lots of staticy crap sound for
// several seconds).
//
// Compromise:
// When an overrun occurs, we adapt by discarding a portion of the buffer.
// The older portion of the buffer is discarded rather than incoming data,
// so that the overall audio synchronization is better.
int free = m_size - _GetApproximateDataInBuffer(); // -1, but the <= handles that
if( free <= nSamples )
{
// Disabled since the lock-free queue can't handle changing the read end from the write thread
#if 0
// Buffer overrun!
// Dump samples from the read portion of the buffer instead of dropping
// the newly written stuff.
s32 comp;
if( SynchMode == 0 ) // TimeStrech on
{
comp = timeStretchOverrun();
}
else
{
// Toss half the buffer plus whatever's being written anew:
comp = GetAlignedBufferSize( (m_size + nSamples ) / 16 );
if( comp > (m_size-SndOutPacketSize) ) comp = m_size-SndOutPacketSize;
}
_DropSamples_Internal(comp);
if( MsgOverruns() )
ConLog(" * SPU2 > Overrun Compensation (%d packets tossed)\n", comp / SndOutPacketSize );
lastPct = 0.0; // normalize the timestretcher
#else
if( MsgOverruns() )
ConLog(" * SPU2 > Overrun! 1 packet tossed)\n");
lastPct = 0.0; // normalize the timestretcher
return;
#endif
}
_WriteSamples_Safe(bData, nSamples);
}
// Calculate the buffer status percentage.
// Returns range from -1.0 to 1.0
// 1.0 = buffer overflow!
// 0.0 = buffer nominal (50% full)
// -1.0 = buffer underflow!
float SndBuffer::GetStatusPct()
{
// Get the buffer status of the output driver too, so that we can
// obtain a more accurate overall buffer status.
int drvempty = mods[OutputModule]->GetEmptySampleCount(); // / 2;
//ConLog( "Data %d >>> driver: %d predict: %d\n", m_data, drvempty, m_predictData );
int data = _GetApproximateDataInBuffer();
float result = (float)(data + m_predictData - drvempty) - (m_size / 16);
result /= (m_size / 16);
return result;
}
// Returns TRUE if there is data to be output, or false if no data
// is available to be copied.
bool SndBuffer::CheckUnderrunStatus( int& nSamples, int& quietSampleCount )
{
quietSampleCount = 0;
int data = _GetApproximateDataInBuffer();
if( m_underrun_freeze )
{
int toFill = m_size / ( (SynchMode == 2) ? 32 : 400); // TimeStretch and Async off?
toFill = GetAlignedBufferSize( toFill );
// toFill is now aligned to a SndOutPacket
if( data < toFill )
{
quietSampleCount = nSamples;
return false;
}
m_underrun_freeze = false;
if( MsgOverruns() )
ConLog(" * SPU2 > Underrun compensation (%d packets buffered)\n", toFill / SndOutPacketSize );
lastPct = 0.0; // normalize timestretcher
}
else if( data < nSamples )
{
nSamples = data;
quietSampleCount = SndOutPacketSize - data;
m_underrun_freeze = true;
if( SynchMode == 0 ) // TimeStrech on
timeStretchUnderrun();
return nSamples != 0;
}
return true;
}
//actual stretch algorithm implementation
void SndBuffer::UpdateTempoChangeSoundTouch2()
{
long targetSamplesReservoir = 48 * SndOutLatencyMS; //48000*SndOutLatencyMS/1000
//base aim at buffer filled %
float baseTargetFullness = (double)targetSamplesReservoir; ///(double)m_size;//0.05;
//state vars
static bool inside_hysteresis; //=false;
static int hys_ok_count; //=0;
static float dynamicTargetFullness; //=baseTargetFullness;
if (gRequestStretcherReset >= STRETCHER_RESET_THRESHOLD) {
ConLog("______> stretch: Reset.\n");
inside_hysteresis = false;
hys_ok_count = 0;
dynamicTargetFullness = baseTargetFullness;
}
int data = _GetApproximateDataInBuffer();
float bufferFullness = (float)data; ///(float)m_size;
#ifdef NEWSTRETCHER_USE_DYNAMIC_TUNING
{ //test current iterations/sec every 0.5s, and change algo params accordingly if different than previous IPS more than 30%
static long iters = 0;
static wxDateTime last = wxDateTime::UNow();
wxDateTime unow = wxDateTime::UNow();
wxTimeSpan delta = unow.Subtract(last);
if (delta.GetMilliseconds() > 500) {
int pot_targetIPS = 1000.0 / delta.GetMilliseconds().ToDouble() * iters;
if (!IsInRange(pot_targetIPS, int((float)targetIPS / 1.3f), int((float)targetIPS * 1.3f))) {
if (MsgOverruns())
ConLog("Stretcher: setting iters/sec from %d to %d\n", targetIPS, pot_targetIPS);
targetIPS = pot_targetIPS;
AVERAGING_WINDOW = GetClamped((int)(50.0f * (float)targetIPS / 750.0f), 3, (int)AVERAGING_BUFFER_SIZE);
}
last = unow;
iters = 0;
}
iters++;
}
#endif
//Algorithm params: (threshold params (hysteresis), etc)
const float hys_ok_factor = 1.04f;
const float hys_bad_factor = 1.2f;
int hys_min_ok_count = GetClamped((int)(50.0 * (float)targetIPS / 750.0), 2, 100); //consecutive iterations within hys_ok before going to 1:1 mode
int compensationDivider = GetClamped((int)(100.0 * (float)targetIPS / 750), 15, 150);
float tempoAdjust = bufferFullness / dynamicTargetFullness;
float avgerage = addToAvg(tempoAdjust);
tempoAdjust = avgerage;
// Dampen the adjustment to avoid overshoots (this means the average will compensate to the other side).
// This is different than simply bigger averaging window since bigger window also has bigger "momentum",
// so it's slower to slow down when it gets close to the equilibrium state and can therefore resonate.
// The dampening (sqrt was chosen for no very good reason) manages to mostly prevent that.
tempoAdjust = sqrt(tempoAdjust);
tempoAdjust = GetClamped(tempoAdjust, 0.05f, 10.0f);
if (tempoAdjust < 1)
baseTargetFullness /= sqrt(tempoAdjust); // slightly increase latency when running slow.
dynamicTargetFullness += (baseTargetFullness / tempoAdjust - dynamicTargetFullness) / (double)compensationDivider;
if (IsInRange(tempoAdjust, 0.9f, 1.1f) && IsInRange(dynamicTargetFullness, baseTargetFullness * 0.9f, baseTargetFullness * 1.1f))
dynamicTargetFullness = baseTargetFullness;
if (!inside_hysteresis) {
if (IsInRange(tempoAdjust, 1.0f / hys_ok_factor, hys_ok_factor))
hys_ok_count++;
else
hys_ok_count = 0;
if (hys_ok_count >= hys_min_ok_count) {
inside_hysteresis = true;
if (MsgOverruns())
ConLog("======> stretch: None (1:1)\n");
}
} else if (!IsInRange(tempoAdjust, 1.0f / hys_bad_factor, hys_bad_factor)) {
if (MsgOverruns())
ConLog("~~~~~~> stretch: Dynamic\n");
inside_hysteresis = false;
hys_ok_count = 0;
}
if (inside_hysteresis)
tempoAdjust = 1.0;
if (MsgOverruns()) {
static int iters = 0;
static wxDateTime last = wxDateTime::UNow();
wxDateTime unow = wxDateTime::UNow();
wxTimeSpan delta = unow.Subtract(last);
if (delta.GetMilliseconds() > 1000) { //report buffers state and tempo adjust every second
ConLog("buffers: %4d ms (%3.0f%%), tempo: %f, comp: %2.3f, iters: %d, (N-IPS:%d -> avg:%d, minokc:%d, div:%d) reset:%d\n",
(int)(data / 48), (double)(100.0 * bufferFullness / baseTargetFullness), (double)tempoAdjust, (double)(dynamicTargetFullness / baseTargetFullness), iters, (int)targetIPS, AVERAGING_WINDOW, hys_min_ok_count, compensationDivider, gRequestStretcherReset);
last = unow;
iters = 0;
}
iters++;
}
pSoundTouch->setTempo(tempoAdjust);
if (gRequestStretcherReset >= STRETCHER_RESET_THRESHOLD)
gRequestStretcherReset = 0;
return;
}
