void ResamplingAudioSource::prepareToPlay (int samplesPerBlockExpected, double sampleRate)
{
const SpinLock::ScopedLockType sl (ratioLock);
const int scaledBlockSize = roundToInt (samplesPerBlockExpected * ratio);
input->prepareToPlay (scaledBlockSize, sampleRate * ratio);
buffer.setSize (numChannels, scaledBlockSize + 32);
filterStates.calloc ((size_t) numChannels);
srcBuffers.calloc ((size_t) numChannels);
destBuffers.calloc ((size_t) numChannels);
createLowPass (ratio);
flushBuffers();
}
void ResamplingAudioSource::prepareToPlay (int samplesPerBlockExpected,
double sampleRate)
{
const SpinLock::ScopedLockType sl (ratioLock);
input->prepareToPlay (samplesPerBlockExpected, sampleRate);
buffer.setSize (numChannels, roundToInt (samplesPerBlockExpected * ratio) + 32);
buffer.clear();
sampsInBuffer = 0;
bufferPos = 0;
subSampleOffset = 0.0;
filterStates.calloc ((size_t) numChannels);
srcBuffers.calloc ((size_t) numChannels);
destBuffers.calloc ((size_t) numChannels);
createLowPass (ratio);
resetFilters();
}
void ResamplingAudioSource::getNextAudioBlock (const AudioSourceChannelInfo& info)
{
double localRatio;
{
const SpinLock::ScopedLockType sl (ratioLock);
localRatio = ratio;
}
if (lastRatio != localRatio)
{
createLowPass (localRatio);
lastRatio = localRatio;
}
const int sampsNeeded = roundToInt (info.numSamples * localRatio) + 3;
int bufferSize = buffer.getNumSamples();
if (bufferSize < sampsNeeded + 8)
{
bufferPos %= bufferSize;
bufferSize = sampsNeeded + 32;
buffer.setSize (buffer.getNumChannels(), bufferSize, true, true);
}
bufferPos %= bufferSize;
int endOfBufferPos = bufferPos + sampsInBuffer;
const int channelsToProcess = jmin (numChannels, info.buffer->getNumChannels());
while (sampsNeeded > sampsInBuffer)
{
endOfBufferPos %= bufferSize;
int numToDo = jmin (sampsNeeded - sampsInBuffer,
bufferSize - endOfBufferPos);
AudioSourceChannelInfo readInfo (&buffer, endOfBufferPos, numToDo);
input->getNextAudioBlock (readInfo);
if (localRatio > 1.0001)
{
// for down-sampling, pre-apply the filter..
for (int i = channelsToProcess; --i >= 0;)
applyFilter (buffer.getWritePointer (i, endOfBufferPos), numToDo, filterStates[i]);
}
sampsInBuffer += numToDo;
endOfBufferPos += numToDo;
}
for (int channel = 0; channel < channelsToProcess; ++channel)
{
destBuffers[channel] = info.buffer->getWritePointer (channel, info.startSample);
srcBuffers[channel] = buffer.getReadPointer (channel);
}
int nextPos = (bufferPos + 1) % bufferSize;
for (int m = info.numSamples; --m >= 0;)
{
jassert (sampsInBuffer > 0 && nextPos != endOfBufferPos);
const float alpha = (float) subSampleOffset;
for (int channel = 0; channel < channelsToProcess; ++channel)
*destBuffers[channel]++ = srcBuffers[channel][bufferPos]
+ alpha * (srcBuffers[channel][nextPos] - srcBuffers[channel][bufferPos]);
subSampleOffset += localRatio;
while (subSampleOffset >= 1.0)
{
if (++bufferPos >= bufferSize)
bufferPos = 0;
--sampsInBuffer;
nextPos = (bufferPos + 1) % bufferSize;
subSampleOffset -= 1.0;
}
}
if (localRatio < 0.9999)
{
// for up-sampling, apply the filter after transposing..
for (int i = channelsToProcess; --i >= 0;)
applyFilter (info.buffer->getWritePointer (i, info.startSample), info.numSamples, filterStates[i]);
}
else if (localRatio <= 1.0001 && info.numSamples > 0)
{
// if the filter's not currently being applied, keep it stoked with the last couple of samples to avoid discontinuities
for (int i = channelsToProcess; --i >= 0;)
{
const float* const endOfBuffer = info.buffer->getReadPointer (i, info.startSample + info.numSamples - 1);
FilterState& fs = filterStates[i];
if (info.numSamples > 1)
{
fs.y2 = fs.x2 = *(endOfBuffer - 1);
}
else
{
fs.y2 = fs.y1;
fs.x2 = fs.x1;
}
fs.y1 = fs.x1 = *endOfBuffer;
}
}
jassert (sampsInBuffer >= 0);
}
