Dynamically FIFO when OSX requests unexpected frame counts.

media/audio/mac/audio_auhal_mac.h

 // Copyright 2013 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.
 //
 // Implementation notes:
 //
 // - It is recommended to first acquire the native sample rate of the default
 //   output device and then use the same rate when creating this object.
 //   Use AudioManagerMac::HardwareSampleRate() to retrieve the sample rate.
 // - Calling Close() also leads to self destruction.
@@ skipping 10 matching lines @@
 #include <CoreAudio/CoreAudio.h>
 
 #include "base/compiler_specific.h"
 #include "base/synchronization/lock.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
 namespace media {
 
 class AudioManagerMac;
+class AudioPullFifo;
 
 // Implementation of AudioOuputStream for Mac OS X using the
 // AUHAL Audio Unit present in OS 10.4 and later.
 // It is useful for low-latency output with optional synchronized
 // input.
 //
 // Overview of operation:
 // 1) An object of AUHALStream is created by the AudioManager
 // factory: audio_man->MakeAudioStream().
 // 2) Next some thread will call Open(), at that point the underlying
@@ skipping 35 matching lines @@
                             UInt32 bus_number,
                             UInt32 number_of_frames,
                             AudioBufferList* io_data);
 
   OSStatus Render(AudioUnitRenderActionFlags* flags,
                   const AudioTimeStamp* output_time_stamp,
                   UInt32 bus_number,
                   UInt32 number_of_frames,
                   AudioBufferList* io_data);
 
+  // Called by either |audio_fifo_| or Render() to provide audio data.
+  void ProvideInput(int frame_delay, AudioBus* dest);
+
   // Helper method to enable input and output.
   bool EnableIO(bool enable, UInt32 scope);
 
   // Sets the stream format on the AUHAL to PCM Float32 non-interleaved
   // for the given number of channels on the given scope and element.
   // The created stream description will be stored in |desc|.
   bool SetStreamFormat(AudioStreamBasicDescription* desc,
                        int channels,
                        UInt32 scope,
                        UInt32 element);
 
   // Creates the AUHAL, sets its stream format, buffer-size, etc.
   bool ConfigureAUHAL();
 
   // Creates the input and output busses.
   void CreateIOBusses();
 
   // Gets the fixed playout device hardware latency and stores it. Returns 0
   // if not available.
   double GetHardwareLatency();
 
   // Gets the current playout latency value.
   double GetPlayoutLatency(const AudioTimeStamp* output_time_stamp);
 
   // Our creator, the audio manager needs to be notified when we close.
-  AudioManagerMac* manager_;
+  AudioManagerMac* const manager_;
 
-  AudioParameters params_;
+  const AudioParameters params_;
   // For convenience - same as in params_.
-  int input_channels_;
-  int output_channels_;
+  const int input_channels_;
+  const int output_channels_;
 
   // Buffer-size.
-  size_t number_of_frames_;
+  const size_t number_of_frames_;
 
   // Pointer to the object that will provide the audio samples.
   AudioSourceCallback* source_;
 
   // Protects |source_|.  Necessary since Render() calls seem to be in flight
   // when |audio_unit_| is supposedly stopped.  See http://crbug.com/178765.
   base::Lock source_lock_;
 
   // Holds the stream format details such as bitrate.
   AudioStreamBasicDescription input_format_;
   AudioStreamBasicDescription output_format_;
 
   // The audio device to use with the AUHAL.
   // We can potentially handle both input and output with this device.
-  AudioDeviceID device_;
+  const AudioDeviceID device_;
 
   // The AUHAL Audio Unit which talks to |device_|.
   AudioUnit audio_unit_;
 
   // Volume level from 0 to 1.
   float volume_;
 
   // Fixed playout hardware latency in frames.
   double hardware_latency_frames_;
 
   // The flag used to stop the streaming.
   bool stopped_;
 
-  // The flag used to indicate if the AudioManager has been notified of a
-  // potential device change.  Reset to false during Start().
-  bool notified_for_possible_device_change_;
-
   // The input AudioUnit renders its data here.
   scoped_ptr<uint8[]> input_buffer_list_storage_;
   AudioBufferList* input_buffer_list_;
 
   // Holds the actual data for |input_buffer_list_|.
   scoped_ptr<AudioBus> input_bus_;
 
   // Container for retrieving data from AudioSourceCallback::OnMoreIOData().
   scoped_ptr<AudioBus> output_bus_;
 
+  // Dynamically allocated FIFO used when CoreAudio asks for unexpected frame
+  // sizes.
+  scoped_ptr<AudioPullFifo> audio_fifo_;
+
+  // Current buffer delay.  Set by Render().
+  uint32 current_hardware_pending_bytes_;
+
   DISALLOW_COPY_AND_ASSIGN(AUHALStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_