// ---------------------------------------------------------------------------
// fadeInAndOut (STATIC)
// ---------------------------------------------------------------------------
// Add zero-amplitude Breakpoints to the ends of a Partial if necessary.
// Do this to all Partials before distilling to make distillation easier.
//
static void fadeInAndOut( Partial & p, double fadeTime )
{
if ( p.first().amplitude() != 0 )
{
p.insert(
p.startTime() - fadeTime,
BreakpointUtils::makeNullBefore( p.first(), fadeTime ) );
}
if ( p.last().amplitude() != 0 )
{
p.insert(
p.endTime() + fadeTime,
BreakpointUtils::makeNullAfter( p.last(), fadeTime ) );
}
}
// ---------------------------------------------------------------------------
// synthesize
// ---------------------------------------------------------------------------
//! Synthesize a bandwidth-enhanced sinusoidal Partial. Zero-amplitude
//! Breakpoints are inserted at either end of the Partial to reduce
//! turn-on and turn-off artifacts, as described above. The synthesizer
//! will resize the buffer as necessary to accommodate all the samples,
//! including the fade out. Previous contents of the buffer are not
//! overwritten. Partials with start times earlier than the Partial fade
//! time will have shorter onset fades. Partials are not rendered at
//! frequencies above the half-sample rate.
//!
//! \param p The Partial to synthesize.
//! \return Nothing.
//! \pre The partial must have non-negative start time.
//! \post This Synthesizer's sample buffer (vector) has been
//! resized to accommodate the entire duration of the
//! Partial, p, including fade out at the end.
//! \throw InvalidPartial if the Partial has negative start time.
//
void
Synthesizer::synthesize( Partial p )
{
if ( p.numBreakpoints() == 0 )
{
debugger << "Synthesizer ignoring a partial that contains no Breakpoints" << endl;
return;
}
if ( p.startTime() < 0 )
{
Throw( InvalidPartial, "Tried to synthesize a Partial having start time less than 0." );
}
debugger << "synthesizing Partial from " << p.startTime() * m_srateHz
<< " to " << p.endTime() * m_srateHz << " starting phase "
<< p.initialPhase() << " starting frequency "
<< p.first().frequency() << endl;
// better to compute this only once:
const double OneOverSrate = 1. / m_srateHz;
// use a Resampler to quantize the Breakpoint times and
// correct the phases:
Resampler quantizer( OneOverSrate );
quantizer.setPhaseCorrect( true );
quantizer.quantize( p );
// resize the sample buffer if necessary:
typedef unsigned long index_type;
index_type endSamp = index_type( ( p.endTime() + m_fadeTimeSec ) * m_srateHz );
if ( endSamp+1 > m_sampleBuffer->size() )
{
// pad by one sample:
m_sampleBuffer->resize( endSamp+1 );
}
// compute the starting time for synthesis of this Partial,
// m_fadeTimeSec before the Partial's startTime, but not before 0:
double itime = ( m_fadeTimeSec < p.startTime() ) ? ( p.startTime() - m_fadeTimeSec ) : 0.;
index_type currentSamp = index_type( (itime * m_srateHz) + 0.5 ); // cheap rounding
// reset the oscillator:
// all that really needs to happen here is setting the frequency
// correctly, the phase will be reset again in the loop over
// Breakpoints below, and the amp and bw can start at 0.
m_osc.resetEnvelopes( BreakpointUtils::makeNullBefore( p.first(), p.startTime() - itime ), m_srateHz );
// cache the previous frequency (in Hz) so that it
// can be used to reset the phase when necessary
// in the sample computation loop below (this saves
// having to recompute from the oscillator's radian
// frequency):
double prevFrequency = p.first().frequency();
// synthesize linear-frequency segments until
// there aren't any more Breakpoints to make segments:
double * bufferBegin = &( m_sampleBuffer->front() );
for ( Partial::const_iterator it = p.begin(); it != p.end(); ++it )
{
index_type tgtSamp = index_type( (it.time() * m_srateHz) + 0.5 ); // cheap rounding
Assert( tgtSamp >= currentSamp );
// if the current oscillator amplitude is
// zero, and the target Breakpoint amplitude
// is not, reset the oscillator phase so that
// it matches exactly the target Breakpoint
// phase at tgtSamp:
if ( m_osc.amplitude() == 0. )
{
// recompute the phase so that it is correct
// at the target Breakpoint (need to do this
// because the null Breakpoint phase was computed
// from an interval in seconds, not samples, so
// it might be inaccurate):
//
// double favg = 0.5 * ( prevFrequency + it.breakpoint().frequency() );
// double dphase = 2 * Pi * favg * ( tgtSamp - currentSamp ) / m_srateHz;
//
double dphase = Pi * ( prevFrequency + it.breakpoint().frequency() )
* ( tgtSamp - currentSamp ) * OneOverSrate;
m_osc.setPhase( it.breakpoint().phase() - dphase );
}
m_osc.oscillate( bufferBegin + currentSamp, bufferBegin + tgtSamp,
it.breakpoint(), m_srateHz );
currentSamp = tgtSamp;
// remember the frequency, may need it to reset the
// phase if a Null Breakpoint is encountered:
prevFrequency = it.breakpoint().frequency();
}
// render a fade out segment:
m_osc.oscillate( bufferBegin + currentSamp, bufferBegin + endSamp,
BreakpointUtils::makeNullAfter( p.last(), m_fadeTimeSec ), m_srateHz );
}