void processSamplesDown (dsp::AudioBlock<SampleType> &outputBlock) override
{
jassert (outputBlock.getNumChannels() <= static_cast<size_t> (OversamplingEngine<SampleType>::buffer.getNumChannels()));
jassert (outputBlock.getNumSamples() * OversamplingEngine<SampleType>::factor <= static_cast<size_t> (OversamplingEngine<SampleType>::buffer.getNumSamples()));
// Initialization
auto fir = coefficientsDown.getRawCoefficients();
auto N = coefficientsDown.getFilterOrder() + 1;
auto Ndiv2 = N / 2;
auto Ndiv4 = Ndiv2 / 2;
auto numSamples = outputBlock.getNumSamples();
// Processing
for (size_t channel = 0; channel < outputBlock.getNumChannels(); channel++)
{
auto bufferSamples = OversamplingEngine<SampleType>::buffer.getWritePointer (static_cast<int> (channel));
auto buf = stateDown.getWritePointer (static_cast<int> (channel));
auto buf2 = stateDown2.getWritePointer (static_cast<int> (channel));
auto samples = outputBlock.getChannelPointer (channel);
auto pos = position.getUnchecked (static_cast<int> (channel));
for (size_t i = 0; i < numSamples; i++)
{
// Input
buf[N - 1] = bufferSamples[i << 1];
// Convolution
auto out = static_cast<SampleType> (0.0);
for (size_t k = 0; k < Ndiv2; k += 2)
out += (buf[k] + buf[N - k - 1]) * fir[k];
// Output
out += buf2[pos] * fir[Ndiv2];
buf2[pos] = bufferSamples[(i << 1) + 1];
samples[i] = out;
// Shift data
for (size_t k = 0; k < N - 2; k++)
buf[k] = buf[k + 2];
// Circular buffer
pos = (pos == 0 ? Ndiv4 : pos - 1);
}
position.setUnchecked (static_cast<int> (channel), pos);
}
}
void processSamplesUp (dsp::AudioBlock<SampleType> &inputBlock) override
{
jassert (inputBlock.getNumChannels() <= static_cast<size_t> (OversamplingEngine<SampleType>::buffer.getNumChannels()));
jassert (inputBlock.getNumSamples() * OversamplingEngine<SampleType>::factor <= static_cast<size_t> (OversamplingEngine<SampleType>::buffer.getNumSamples()));
// Initialization
auto fir = coefficientsUp.getRawCoefficients();
auto N = coefficientsUp.getFilterOrder() + 1;
auto Ndiv2 = N / 2;
auto numSamples = inputBlock.getNumSamples();
// Processing
for (size_t channel = 0; channel < inputBlock.getNumChannels(); channel++)
{
auto bufferSamples = OversamplingEngine<SampleType>::buffer.getWritePointer (static_cast<int> (channel));
auto buf = stateUp.getWritePointer (static_cast<int> (channel));
auto samples = inputBlock.getChannelPointer (channel);
for (size_t i = 0; i < numSamples; i++)
{
// Input
buf[N - 1] = 2 * samples[i];
// Convolution
auto out = static_cast<SampleType> (0.0);
for (size_t k = 0; k < Ndiv2; k += 2)
out += (buf[k] + buf[N - k - 1]) * fir[k];
// Outputs
bufferSamples[i << 1] = out;
bufferSamples[(i << 1) + 1] = buf[Ndiv2 + 1] * fir[Ndiv2];
// Shift data
for (size_t k = 0; k < N - 2; k += 2)
buf[k] = buf[k + 2];
}
}
}
void Oversampling<SampleType>::processSamplesDown (dsp::AudioBlock<SampleType>& outputBlock) noexcept
{
jassert (! stages.isEmpty());
if (! isReady)
return;
auto currentNumSamples = outputBlock.getNumSamples();
for (int n = 0; n < stages.size() - 1; ++n)
currentNumSamples *= stages.getUnchecked(n)->factor;
for (int n = stages.size() - 1; n > 0; --n)
{
auto& stage = *stages.getUnchecked(n);
auto audioBlock = stages.getUnchecked (n - 1)->getProcessedSamples (currentNumSamples);
stage.processSamplesDown (audioBlock);
currentNumSamples /= stage.factor;
}
stages.getFirst()->processSamplesDown (outputBlock);
}