Simplified AudioOutputStream interface.

1. Removed packet_size parameter from Open().
2. Removed OnClose() from the callback. Now the callback is guaranteed to be called only between Start() and Stop().
3. Added samples_per_packet in the AudioParameters struct.

BUG=39825
TEST=Unittests

Review URL: http://codereview.chromium.org/4661001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@65766 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 7 deletions

diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index 805db89..26f0acf 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -12,6 +12,9 @@ class AudioInputStream;
 class AudioOutputStream;
 class MessageLoop;
 
+// TODO(sergeyu): In this interface and some other places AudioParameters struct
+// is passed by value. It is better to change it to const reference.
+
 // Manages all audio resources. In particular it owns the AudioOutputStream
 // objects. Provides some convenience functions that avoid the need to provide
 // iterators over the existing streams.
@@ -26,14 +29,19 @@ class AudioManager {
   // sample rates.
   virtual bool HasAudioInputDevices() = 0;
 
-  // Factory for all the supported stream formats. The |channels| can be 1 to 5.
-  // The |sample_rate| is in hertz and can be any value supported by the
-  // platform. For some future formats the |sample_rate| and |bits_per_sample|
-  // can take special values.
+  // Factory for all the supported stream formats. |params| defines parameters
+  // of the audio stream to be created.
+  //
+  // |params.sample_per_packet| is the requested buffer allocation which the
+  // audio source thinks it can usually fill without blocking. Internally two
+  // or three buffers are created, one will be locked for playback and one will
+  // be ready to be filled in the call to AudioSourceCallback::OnMoreData().
+  //
   // Returns NULL if the combination of the parameters is not supported, or if
   // we have reached some other platform specific limit.
   //
-  // AUDIO_PCM_LOW_LATENCY can be passed to this method and it has two effects:
+  // |params.format| can be set to AUDIO_PCM_LOW_LATENCY and that has two
+  // effects:
   // 1- Instead of triple buffered the audio will be double buffered.
   // 2- A low latency driver or alternative audio subsystem will be used when
   //    available.
@@ -53,8 +61,7 @@ class AudioManager {
   //
   // Do not free the returned AudioInputStream. It is owned by AudioManager.
   // When you are done with it, call |Stop()| and |Close()| to release it.
-  virtual AudioInputStream* MakeAudioInputStream(AudioParameters params,
-                                                 int samples_per_packet) = 0;
+  virtual AudioInputStream* MakeAudioInputStream(AudioParameters params) = 0;
 
   // Muting continues playback but effectively the volume is set to zero.
   // Un-muting returns the volume to the previous level.