126 lines
4.6 KiB
C++
126 lines
4.6 KiB
C++
/*
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_COMMON_AUDIO_LAPPED_TRANSFORM_H_
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#define WEBRTC_COMMON_AUDIO_LAPPED_TRANSFORM_H_
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#include <complex>
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#include <memory>
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#include "webrtc/common_audio/blocker.h"
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#include "webrtc/common_audio/real_fourier.h"
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#include "webrtc/system_wrappers/include/aligned_array.h"
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namespace webrtc {
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// Helper class for audio processing modules which operate on frequency domain
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// input derived from the windowed time domain audio stream.
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//
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// The input audio chunk is sliced into possibly overlapping blocks, multiplied
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// by a window and transformed with an FFT implementation. The transformed data
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// is supplied to the given callback for processing. The processed output is
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// then inverse transformed into the time domain and spliced back into a chunk
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// which constitutes the final output of this processing module.
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class LappedTransform {
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public:
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class Callback {
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public:
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virtual ~Callback() {}
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virtual void ProcessAudioBlock(const std::complex<float>* const* in_block,
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size_t num_in_channels, size_t frames,
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size_t num_out_channels,
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std::complex<float>* const* out_block) = 0;
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};
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// Construct a transform instance. |chunk_length| is the number of samples in
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// each channel. |window| defines the window, owned by the caller (a copy is
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// made internally); |window| should have length equal to |block_length|.
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// |block_length| defines the length of a block, in samples.
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// |shift_amount| is in samples. |callback| is the caller-owned audio
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// processing function called for each block of the input chunk.
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LappedTransform(size_t num_in_channels,
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size_t num_out_channels,
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size_t chunk_length,
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const float* window,
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size_t block_length,
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size_t shift_amount,
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Callback* callback);
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~LappedTransform() {}
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// Main audio processing helper method. Internally slices |in_chunk| into
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// blocks, transforms them to frequency domain, calls the callback for each
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// block and returns a de-blocked time domain chunk of audio through
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// |out_chunk|. Both buffers are caller-owned.
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void ProcessChunk(const float* const* in_chunk, float* const* out_chunk);
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// Get the chunk length.
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//
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// The chunk length is the number of samples per channel that must be passed
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// to ProcessChunk via the parameter in_chunk.
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//
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// Returns the same chunk_length passed to the LappedTransform constructor.
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size_t chunk_length() const { return chunk_length_; }
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// Get the number of input channels.
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//
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// This is the number of arrays that must be passed to ProcessChunk via
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// in_chunk.
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//
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// Returns the same num_in_channels passed to the LappedTransform constructor.
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size_t num_in_channels() const { return num_in_channels_; }
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// Get the number of output channels.
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//
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// This is the number of arrays that must be passed to ProcessChunk via
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// out_chunk.
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//
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// Returns the same num_out_channels passed to the LappedTransform
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// constructor.
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size_t num_out_channels() const { return num_out_channels_; }
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private:
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// Internal middleware callback, given to the blocker. Transforms each block
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// and hands it over to the processing method given at construction time.
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class BlockThunk : public BlockerCallback {
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public:
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explicit BlockThunk(LappedTransform* parent) : parent_(parent) {}
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virtual void ProcessBlock(const float* const* input,
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size_t num_frames,
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size_t num_input_channels,
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size_t num_output_channels,
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float* const* output);
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private:
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LappedTransform* const parent_;
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} blocker_callback_;
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const size_t num_in_channels_;
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const size_t num_out_channels_;
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const size_t block_length_;
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const size_t chunk_length_;
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Callback* const block_processor_;
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Blocker blocker_;
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std::unique_ptr<RealFourier> fft_;
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const size_t cplx_length_;
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AlignedArray<float> real_buf_;
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AlignedArray<std::complex<float> > cplx_pre_;
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AlignedArray<std::complex<float> > cplx_post_;
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};
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} // namespace webrtc
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#endif // WEBRTC_COMMON_AUDIO_LAPPED_TRANSFORM_H_
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