Add Mac OS X synchronized audio I/O back-end

media/base/audio_bus.h

 // Copyright (c) 2012 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_BUS_H_
 #define MEDIA_BASE_AUDIO_BUS_H_
 
 #include <vector>
 
 #include "base/memory/aligned_memory.h"
@@ skipping 12 matching lines @@
  public:
   // Guaranteed alignment of each channel's data; use 16-byte alignment for easy
   // SSE optimizations.
   enum { kChannelAlignment = 16 };
 
   // Creates a new AudioBus and allocates |channels| of length |frames|.  Uses
   // channels() and frames_per_buffer() from AudioParameters if given.
   static scoped_ptr<AudioBus> Create(int channels, int frames);
   static scoped_ptr<AudioBus> Create(const AudioParameters& params);
 
+  // Creates a new AudioBus with the given number of channels, but zero length.
+  // It's expected to be used with SetChannelData() and set_frames() to
+  // wrap externally allocated memory.
+  static scoped_ptr<AudioBus> CreateWrapper(int channels);
+
   // Creates a new AudioBus from an existing channel vector.  Does not transfer
   // ownership of |channel_data| to AudioBus; i.e., |channel_data| must outlive
   // the returned AudioBus.  Each channel must be aligned by kChannelAlignment.
   static scoped_ptr<AudioBus> WrapVector(
       int frames, const std::vector<float*>& channel_data);
 
   // Creates a new AudioBus by wrapping an existing block of memory.  Block must
   // be at least CalculateMemorySize() bytes in size.  |data| must outlive the
   // returned AudioBus.  |data| must be aligned by kChannelAlignment.
   static scoped_ptr<AudioBus> WrapMemory(int channels, int frames, void* data);
@@ skipping 24 matching lines @@
 
   // Helper method for copying channel data from one AudioBus to another.  Both
   // AudioBus object must have the same frames() and channels().
   void CopyTo(AudioBus* dest) const;
 
   // Returns a raw pointer to the requested channel.  Pointer is guaranteed to
   // have a 16-byte alignment.  Warning: Do not rely on having sane (i.e. not
   // inf, nan, or between [-1.0, 1.0]) values in the channel data.
   float* channel(int channel) { return channel_data_[channel]; }
   const float* channel(int channel) const { return channel_data_[channel]; }
+  void SetChannelData(int channel, float* data);
 
   int channels() const { return channel_data_.size(); }
   int frames() const { return frames_; }
+  void set_frames(int frames);
 
   // Helper method for zeroing out all channels of audio data.
   void Zero();
   void ZeroFrames(int frames);
   void ZeroFramesPartial(int start_frame, int frames);
 
  private:
   friend class scoped_ptr<AudioBus>;
   ~AudioBus();
 
   AudioBus(int channels, int frames);
   AudioBus(int channels, int frames, float* data);
   AudioBus(int frames, const std::vector<float*>& channel_data);
+  explicit AudioBus(int channels);
 
   // Helper method for building |channel_data_| from a block of memory.  |data|
   // must be at least BlockSize() bytes in size.
   void BuildChannelData(int channels, int aligned_frame, float* data);
 
   // Contiguous block of channel memory.
   scoped_ptr_malloc<float, base::ScopedPtrAlignedFree> data_;
 
   std::vector<float*> channel_data_;
   int frames_;
 
+  // Protect SetChannelData() and set_frames() for use by CreateWrapper().
+  bool can_set_channel_data_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioBus);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_BUS_H_