Adding input and output delay estimation for mac.

media/audio/mac/audio_low_latency_input_mac.h

Index: media/audio/mac/audio_low_latency_input_mac.h
===================================================================
--- media/audio/mac/audio_low_latency_input_mac.h	(revision 104447)
+++ media/audio/mac/audio_low_latency_input_mac.h	(working copy)
@@ -27,6 +27,10 @@
 //   input device and then use the same rate when creating this object.
 //   Use AUAudioInputStream::HardwareSampleRate() to retrieve the sample rate.
 // - Calling Close() also leads to self destruction.
+// - The latency consists of two parts: 1, hardware latency, which includes

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

Can be cleaned up. Thanks.

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+//   Audio Unit latency, audio device latency and audio stream latency; 2,
+//   the delay between now and the scheduled time stamp that tells when the
+//   data we are providing is going to hit the hardware.
 //
 #ifndef MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
@@ -67,14 +71,22 @@
   // AudioOutputUnit callback.
   static OSStatus InputProc(void* user_data,
                             AudioUnitRenderActionFlags* flags,
-                            const AudioTimeStamp* time_stamp,
+                            const AudioTimeStamp* output_time_stamp,

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

remove output

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

                             UInt32 bus_number,
                             UInt32 number_of_frames,
                             AudioBufferList* io_data);
 
   // Pushes recorded data to consumer of the input audio stream.
-  OSStatus Provide(UInt32 number_of_frames, AudioBufferList* io_data);
+  OSStatus Provide(UInt32 number_of_frames, AudioBufferList* io_data,
+                   const AudioTimeStamp* time_stamp);
 
+  // Get capture hardware latency, this is called only when initiating

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

"Gets the fixed capture hardware latency and stores it during initialization".

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  // the input Audio Unit.

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

I would remove 'input' and call the method StoreHardwareLatency() instead.

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  void UpdateHardwareLatency();
+
+  // Update capture delay value.

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

Updates the current capture delay value.

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  void UpdateCaptureLatency(const AudioTimeStamp* input_time_stamp);
+
   // Issues the OnError() callback to the |sink_|.
   void HandleError(OSStatus err);
 
@@ -96,6 +108,9 @@
   // The AUHAL also enables selection of non default devices.
   AudioUnit audio_unit_;
 
+  // The UID refers to the input audio device.

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

Which device?

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  AudioDeviceID input_device_id_;
+
   // Provides a mechanism for encapsulating one or more buffers of audio data.
   AudioBufferList audio_buffer_list_;
 
@@ -106,6 +121,13 @@
   // True after successfull Start(), false after successful Stop().
   bool started_;
 
+  // Capture hardware latency in millisecond, the value is updated when

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

Remove last part (, the value). Add 'fixed'.

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  // initiating the input Audio Unit.
+  uint32 hardware_latency_ms_;
+
+  // Capture latency in millisecond.

[henrika (OOO until Aug 14), 2011/10/12 12:10:11]

Current ..

[no longer working on chromium, 2011/10/12 15:28:47]

Done.

+  uint32 capture_latency_ms_;
+
   DISALLOW_COPY_AND_ASSIGN(AUAudioInputStream);
 };