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_COMMON_AUDIO_LAPPED_TRANSFORM_H_
      12             : #define WEBRTC_COMMON_AUDIO_LAPPED_TRANSFORM_H_
      13             : 
      14             : #include <complex>
      15             : #include <memory>
      16             : 
      17             : #include "webrtc/common_audio/blocker.h"
      18             : #include "webrtc/common_audio/real_fourier.h"
      19             : #include "webrtc/system_wrappers/include/aligned_array.h"
      20             : 
      21             : namespace webrtc {
      22             : 
      23             : // Helper class for audio processing modules which operate on frequency domain
      24             : // input derived from the windowed time domain audio stream.
      25             : //
      26             : // The input audio chunk is sliced into possibly overlapping blocks, multiplied
      27             : // by a window and transformed with an FFT implementation. The transformed data
      28             : // is supplied to the given callback for processing. The processed output is
      29             : // then inverse transformed into the time domain and spliced back into a chunk
      30             : // which constitutes the final output of this processing module.
      31           0 : class LappedTransform {
      32             :  public:
      33           0 :   class Callback {
      34             :    public:
      35           0 :     virtual ~Callback() {}
      36             : 
      37             :     virtual void ProcessAudioBlock(const std::complex<float>* const* in_block,
      38             :                                    size_t num_in_channels, size_t frames,
      39             :                                    size_t num_out_channels,
      40             :                                    std::complex<float>* const* out_block) = 0;
      41             :   };
      42             : 
      43             :   // Construct a transform instance. |chunk_length| is the number of samples in
      44             :   // each channel. |window| defines the window, owned by the caller (a copy is
      45             :   // made internally); |window| should have length equal to |block_length|.
      46             :   // |block_length| defines the length of a block, in samples.
      47             :   // |shift_amount| is in samples. |callback| is the caller-owned audio
      48             :   // processing function called for each block of the input chunk.
      49             :   LappedTransform(size_t num_in_channels,
      50             :                   size_t num_out_channels,
      51             :                   size_t chunk_length,
      52             :                   const float* window,
      53             :                   size_t block_length,
      54             :                   size_t shift_amount,
      55             :                   Callback* callback);
      56             :   ~LappedTransform();
      57             : 
      58             :   // Main audio processing helper method. Internally slices |in_chunk| into
      59             :   // blocks, transforms them to frequency domain, calls the callback for each
      60             :   // block and returns a de-blocked time domain chunk of audio through
      61             :   // |out_chunk|. Both buffers are caller-owned.
      62             :   void ProcessChunk(const float* const* in_chunk, float* const* out_chunk);
      63             : 
      64             :   // Get the chunk length.
      65             :   //
      66             :   // The chunk length is the number of samples per channel that must be passed
      67             :   // to ProcessChunk via the parameter in_chunk.
      68             :   //
      69             :   // Returns the same chunk_length passed to the LappedTransform constructor.
      70             :   size_t chunk_length() const { return chunk_length_; }
      71             : 
      72             :   // Get the number of input channels.
      73             :   //
      74             :   // This is the number of arrays that must be passed to ProcessChunk via
      75             :   // in_chunk.
      76             :   //
      77             :   // Returns the same num_in_channels passed to the LappedTransform constructor.
      78             :   size_t num_in_channels() const { return num_in_channels_; }
      79             : 
      80             :   // Get the number of output channels.
      81             :   //
      82             :   // This is the number of arrays that must be passed to ProcessChunk via
      83             :   // out_chunk.
      84             :   //
      85             :   // Returns the same num_out_channels passed to the LappedTransform
      86             :   // constructor.
      87             :   size_t num_out_channels() const { return num_out_channels_; }
      88             : 
      89             :   // Returns the initial delay.
      90             :   //
      91             :   // This is the delay introduced by the |blocker_| to be able to get and return
      92             :   // chunks of |chunk_length|, but process blocks of |block_length|.
      93             :   size_t initial_delay() const { return blocker_.initial_delay(); }
      94             : 
      95             :  private:
      96             :   // Internal middleware callback, given to the blocker. Transforms each block
      97             :   // and hands it over to the processing method given at construction time.
      98           0 :   class BlockThunk : public BlockerCallback {
      99             :    public:
     100           0 :     explicit BlockThunk(LappedTransform* parent) : parent_(parent) {}
     101             : 
     102             :  void ProcessBlock(const float* const* input,
     103             :                               size_t num_frames,
     104             :                               size_t num_input_channels,
     105             :                               size_t num_output_channels,
     106             :                               float* const* output) override;
     107             : 
     108             :    private:
     109             :     LappedTransform* const parent_;
     110             :   } blocker_callback_;
     111             : 
     112             :   const size_t num_in_channels_;
     113             :   const size_t num_out_channels_;
     114             : 
     115             :   const size_t block_length_;
     116             :   const size_t chunk_length_;
     117             : 
     118             :   Callback* const block_processor_;
     119             :   Blocker blocker_;
     120             : 
     121             :   std::unique_ptr<RealFourier> fft_;
     122             :   const size_t cplx_length_;
     123             :   AlignedArray<float> real_buf_;
     124             :   AlignedArray<std::complex<float> > cplx_pre_;
     125             :   AlignedArray<std::complex<float> > cplx_post_;
     126             : };
     127             : 
     128             : }  // namespace webrtc
     129             : 
     130             : #endif  // WEBRTC_COMMON_AUDIO_LAPPED_TRANSFORM_H_
     131             :