Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_
      12             : #define WEBRTC_MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_
      13             : 
      14             : #include <cstring>
      15             : #include <memory>
      16             : #include <vector>
      17             : 
      18             : #include "webrtc/modules/audio_processing/three_band_filter_bank.h"
      19             : 
      20             : namespace webrtc {
      21             : 
      22             : class IFChannelBuffer;
      23             : 
      24             : struct TwoBandsStates {
      25           0 :   TwoBandsStates() {
      26           0 :     memset(analysis_state1, 0, sizeof(analysis_state1));
      27           0 :     memset(analysis_state2, 0, sizeof(analysis_state2));
      28           0 :     memset(synthesis_state1, 0, sizeof(synthesis_state1));
      29           0 :     memset(synthesis_state2, 0, sizeof(synthesis_state2));
      30           0 :   }
      31             : 
      32             :   static const int kStateSize = 6;
      33             :   int analysis_state1[kStateSize];
      34             :   int analysis_state2[kStateSize];
      35             :   int synthesis_state1[kStateSize];
      36             :   int synthesis_state2[kStateSize];
      37             : };
      38             : 
      39             : // Splitting filter which is able to split into and merge from 2 or 3 frequency
      40             : // bands. The number of channels needs to be provided at construction time.
      41             : //
      42             : // For each block, Analysis() is called to split into bands and then Synthesis()
      43             : // to merge these bands again. The input and output signals are contained in
      44             : // IFChannelBuffers and for the different bands an array of IFChannelBuffers is
      45             : // used.
      46           0 : class SplittingFilter {
      47             :  public:
      48             :   SplittingFilter(size_t num_channels, size_t num_bands, size_t num_frames);
      49             :   ~SplittingFilter();
      50             : 
      51             :   void Analysis(const IFChannelBuffer* data, IFChannelBuffer* bands);
      52             :   void Synthesis(const IFChannelBuffer* bands, IFChannelBuffer* data);
      53             : 
      54             :  private:
      55             :   // Two-band analysis and synthesis work for 640 samples or less.
      56             :   void TwoBandsAnalysis(const IFChannelBuffer* data, IFChannelBuffer* bands);
      57             :   void TwoBandsSynthesis(const IFChannelBuffer* bands, IFChannelBuffer* data);
      58             :   void ThreeBandsAnalysis(const IFChannelBuffer* data, IFChannelBuffer* bands);
      59             :   void ThreeBandsSynthesis(const IFChannelBuffer* bands, IFChannelBuffer* data);
      60             :   void InitBuffers();
      61             : 
      62             :   const size_t num_bands_;
      63             :   std::vector<TwoBandsStates> two_bands_states_;
      64             :   std::vector<std::unique_ptr<ThreeBandFilterBank>> three_band_filter_banks_;
      65             : };
      66             : 
      67             : }  // namespace webrtc
      68             : 
      69             : #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_SPLITTING_FILTER_H_