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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_SIMPLE_FFT_CONVOLVER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_SIMPLE_FFT_CONVOLVER_H_
#include <memory>
#include "third_party/blink/renderer/platform/audio/audio_array.h"
#include "third_party/blink/renderer/platform/audio/fft_frame.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
namespace blink {
// The SimpleFFTConvolver does an FFT convolution. It differs from
// the FFTConvolver in that it restricts the maximum size of
// |convolution_kernel| to |input_block_size|. This restriction allows it to do
// an FFT on every Process call. Therefore, the processing delay of
// the SimpleFFTConvolver is the same as that of the DirectConvolver and thus
// smaller than that of the FFTConvolver.
class SimpleFFTConvolver final {
USING_FAST_MALLOC(SimpleFFTConvolver);
public:
SimpleFFTConvolver(
unsigned input_block_size,
const std::unique_ptr<AudioFloatArray>& convolution_kernel);
SimpleFFTConvolver(const SimpleFFTConvolver&) = delete;
SimpleFFTConvolver& operator=(const SimpleFFTConvolver&) = delete;
void Process(const float* source_p,
float* dest_p,
uint32_t frames_to_process);
void Reset();
uint32_t ConvolutionKernelSize() const { return convolution_kernel_size_; }
private:
unsigned FftSize() const { return frame_.FftSize(); }
uint32_t convolution_kernel_size_;
FFTFrame fft_kernel_;
FFTFrame frame_;
// Buffer input until we get fftSize / 2 samples then do an FFT
AudioFloatArray input_buffer_;
// Stores output which we read a little at a time
AudioFloatArray output_buffer_;
// Saves the 2nd half of the FFT buffer, so we can do an overlap-add with the
// 1st half of the next one
AudioFloatArray last_overlap_buffer_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_SIMPLE_FFT_CONVOLVER_H_
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