Add basic resample support to WASAPIAudioInputStream.

media/base/audio_block_fifo.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_BLOCK_FIFO_H_
 #define MEDIA_BASE_AUDIO_BLOCK_FIFO_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "media/base/audio_bus.h"
@@ skipping 11 matching lines @@
   // Creates a new AudioBlockFifo and allocates |blocks| memory, each block
   // of memory can store |channels| of length |frames| data.
   AudioBlockFifo(int channels, int frames, int blocks);
   virtual ~AudioBlockFifo();
 
   // Pushes interleaved audio data from |source| to the FIFO.
   // The method will deinterleave the data into a audio bus.
   // Push() will crash if the allocated space is insufficient.
   void Push(const void* source, int frames, int bytes_per_sample);
 
+  // Pushes zeroed out frames to the FIFO.
+  void PushSilence(int frames);
+
   // Consumes a block of audio from the FIFO.  Returns an AudioBus which
   // contains the consumed audio data to avoid copying.
   // Consume() will crash if the FIFO does not contain a block of data.
   const AudioBus* Consume();
 
   // Empties the FIFO without deallocating any memory.
   void Clear();
 
   // Number of available block of memory ready to be consumed in the FIFO.
   int available_blocks() const { return available_blocks_; }
 
   // Number of available frames of data in the FIFO.
   int GetAvailableFrames() const;
 
   // Number of unfilled frames in the whole FIFO.
   int GetUnfilledFrames() const;
 
   // Dynamically increase |blocks| of memory to the FIFO.
   void IncreaseCapacity(int blocks);
 
  private:
+  // Common implementation for Push() and PushSilence.  if |source| is nullptr,
+  // silence will be pushed. To push silence, set source and bytes_per_sample to
+  // nullptr and 0 respectively.
+  void PushInternal(const void* source, int frames, int bytes_per_sample);
+
   // The actual FIFO is a vector of audio buses.
   ScopedVector<AudioBus> audio_blocks_;
 
   // Number of channels in AudioBus.
   const int channels_;
 
   // Maximum number of frames of data one block of memory can contain.
   // This value is set by |frames| in the constructor.
   const int block_frames_;
 
   // Used to keep track which block of memory to be written.
   int write_block_;
 
   // Used to keep track which block of memory to be consumed.
   int read_block_;
 
   // Number of available blocks of memory to be consumed.
   int available_blocks_;
 
   // Current write position in the current written block.
   int write_pos_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioBlockFifo);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_BLOCK_FIFO_H_