Method OutputStep

libraries/lib-fft/SpectrumTransformer.cpp:272–324

Formerly part of EffectNoiseReduction::Worker::ReduceNoise()

// Formerly part of EffectNoiseReduction::Worker::ReduceNoise()
void SpectrumTransformer::OutputStep()
{
   if (!mNeedsOutput)
      return;
   if (QueueIsFull()) {
      const auto last = mSpectrumSize - 1;
      Window &record = **mQueue.rbegin();

      const float *pReal = &record.mRealFFTs[1];
      const float *pImag = &record.mImagFFTs[1];
      float *pBuffer = &mFFTBuffer[2];
      auto nn = mSpectrumSize - 2;
      for (; nn--;) {
         *pBuffer++ = *pReal++;
         *pBuffer++ = *pImag++;
      }
      mFFTBuffer[0] = record.mRealFFTs[0];
      // The Fs/2 component is stored as the imaginary part of the DC component
      mFFTBuffer[1] = record.mImagFFTs[0];

      // Invert the FFT into the output buffer
      InverseRealFFTf(mFFTBuffer.data(), hFFT.get());

      // Overlap-add
      if (mOutWindow.size() > 0) {
         auto pOut = mOutOverlapBuffer.data();
         auto pWindow = mOutWindow.data();
         auto pBitReversed = &hFFT->BitReversed[0];
         for (size_t jj = 0; jj < last; ++jj) {
            auto kk = *pBitReversed++;
            *pOut++ += mFFTBuffer[kk] * (*pWindow++);
            *pOut++ += mFFTBuffer[kk + 1] * (*pWindow++);
         }
      }
      else {
         auto pOut = mOutOverlapBuffer.data();
         auto pBitReversed = &hFFT->BitReversed[0];
         for (size_t jj = 0; jj < last; ++jj) {
            auto kk = *pBitReversed++;
            *pOut++ += mFFTBuffer[kk];
            *pOut++ += mFFTBuffer[kk + 1];
         }
      }
      auto buffer = mOutOverlapBuffer.data();
      if (mOutStepCount >= 0) {
         // Output the first portion of the overlap buffer, they're done
         DoOutput(buffer, mStepSize);
      }
      // Shift the remainder over.
      memmove(buffer, buffer + mStepSize, sizeof(float)*(mWindowSize - mStepSize));
      std::fill(buffer + mWindowSize - mStepSize, buffer + mWindowSize, 0.0f);
   }
}

bool SpectrumTransformer::QueueIsFull() const
{