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/*
* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_
#define MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_
#include <cstring>
#include <memory>
#include <vector>
#include "common_audio/channel_buffer.h"
#include "modules/audio_processing/three_band_filter_bank.h"
namespace webrtc {
struct TwoBandsStates {
TwoBandsStates() {
memset(analysis_state1, 0, sizeof(analysis_state1));
memset(analysis_state2, 0, sizeof(analysis_state2));
memset(synthesis_state1, 0, sizeof(synthesis_state1));
memset(synthesis_state2, 0, sizeof(synthesis_state2));
}
static const int kStateSize = 6;
int analysis_state1[kStateSize];
int analysis_state2[kStateSize];
int synthesis_state1[kStateSize];
int synthesis_state2[kStateSize];
};
// Splitting filter which is able to split into and merge from 2 or 3 frequency
// bands. The number of channels needs to be provided at construction time.
//
// For each block, Analysis() is called to split into bands and then Synthesis()
// to merge these bands again. The input and output signals are contained in
// ChannelBuffers and for the different bands an array of ChannelBuffers is
// used.
class SplittingFilter {
public:
SplittingFilter(size_t num_channels, size_t num_bands, size_t num_frames);
~SplittingFilter();
void Analysis(const ChannelBuffer<float>* data, ChannelBuffer<float>* bands);
void Synthesis(const ChannelBuffer<float>* bands, ChannelBuffer<float>* data);
private:
// Two-band analysis and synthesis work for 640 samples or less.
void TwoBandsAnalysis(const ChannelBuffer<float>* data,
ChannelBuffer<float>* bands);
void TwoBandsSynthesis(const ChannelBuffer<float>* bands,
ChannelBuffer<float>* data);
void ThreeBandsAnalysis(const ChannelBuffer<float>* data,
ChannelBuffer<float>* bands);
void ThreeBandsSynthesis(const ChannelBuffer<float>* bands,
ChannelBuffer<float>* data);
void InitBuffers();
const size_t num_bands_;
std::vector<TwoBandsStates> two_bands_states_;
std::vector<ThreeBandFilterBank> three_band_filter_banks_;
};
} // namespace webrtc
#endif // MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_
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