325cff01b4
Add code for doing block-based frequency domain processing. Developed and reviewed in isolation. Corresponding export CL: https://chromereviews.googleplex.com/95187013/ R=bercic@google.com, kjellander@webrtc.org, turaj@webrtc.org Review URL: https://webrtc-codereview.appspot.com/31539004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@7359 4adac7df-926f-26a2-2b94-8c16560cd09d
102 lines
3.7 KiB
C++
102 lines
3.7 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 "webrtc/base/checks.h"
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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/interface/aligned_array.h"
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#include "webrtc/system_wrappers/interface/scoped_ptr.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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int in_channels, int frames,
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int 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); can be NULL to disable windowing entirely.
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// |block_length| defines the length of a block, in samples, even when
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// windowing is disabled. |shift_length| is in samples. |callback| is the
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// caller-owned audio processing function called for each block of the input
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// chunk.
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LappedTransform(int in_channels, int out_channels, int chunk_length,
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const float* window, int block_length, int 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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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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friend class BlockThunk;
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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 ~BlockThunk() {}
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virtual void ProcessBlock(const float* const* input, int num_frames,
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int num_input_channels, int num_output_channels,
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float* const* output);
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private:
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LappedTransform* parent_;
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} blocker_callback_;
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int in_channels_;
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int out_channels_;
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const float* window_;
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bool own_window_;
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int window_shift_amount_;
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int block_length_;
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int chunk_length_;
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Callback* block_processor_;
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scoped_ptr<Blocker> blocker_;
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RealFourier fft_;
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int 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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