//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;
}
//actual stretch algorithm implementation
void SndBuffer::UpdateTempoChangeSoundTouch2()
{
//base aim at buffer filled %
float targetFullness=0.1;
//threshold params (hysteresis)
static const float hys_ok_factor=1.03;
static const int hys_min_ok_count=100; //consecutive iterations within hys_ok before going to 1:1 mode
static const float hys_bad_factor=1.2;
//state vars
static bool inside_hysteresis=false;
static int hys_ok_count=0;
//some precalculated values
static const float hys_ok_min=1.0/hys_ok_factor;
static const float hys_ok_max=hys_ok_factor;
static const float hys_bad_min=1.0/hys_bad_factor;
static const float hys_bad_max=hys_bad_factor;
float bufferFullness=(float)m_data/(float)m_size;
static float last_bufferFullness=0;
if(last_bufferFullness != bufferFullness){// only recalculate if buffer changes
last_bufferFullness = bufferFullness;
float tempoAdjust=bufferFullness/targetFullness;
float avgerage = addToAvg(tempoAdjust);
tempoAdjust = avgerage;
if( tempoAdjust>1.2 ) tempoAdjust=0.2+pow(tempoAdjust-0.2f, 3);//reduce latency for faster speeds only
tempoAdjust = clamp( tempoAdjust, 0.1f, 10.0f);
if( !inside_hysteresis )
{
if( tempoAdjust == clamp( tempoAdjust, hys_ok_min, hys_ok_max ) )
hys_ok_count++;
else
hys_ok_count=0;
if( hys_ok_count >= hys_min_ok_count ){
inside_hysteresis=true;
if(MsgOverruns()) printf("======> stretch: None (1:1)\n");
}
}
else if( tempoAdjust != clamp( tempoAdjust, hys_bad_min, hys_bad_max ) ){
if(MsgOverruns()) printf("~~~~~~> 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
printf("buffers: %f, actual adjust: %f, iterations: %d\n", bufferFullness, tempoAdjust, iters);
last=unow;
iters=0;
}
iters++;
}
pSoundTouch->setTempo(tempoAdjust);
//collect some stats...
if(tempoAdjust==1.0)
ts_stats_normalblocks++;
else
ts_stats_stretchblocks++;
}
return;
}