Adding microphone volume support to chrome.

media/audio/mac/audio_low_latency_input_mac.cc

Index: media/audio/mac/audio_low_latency_input_mac.cc
diff --git a/media/audio/mac/audio_low_latency_input_mac.cc b/media/audio/mac/audio_low_latency_input_mac.cc
index ec97fe9f7ed667a2a561eb8d7fe64ae36a74cbfb..506ca6d329b6b0e2cb268223cc4919b127ea2958 100644
--- a/media/audio/mac/audio_low_latency_input_mac.cc
+++ b/media/audio/mac/audio_low_latency_input_mac.cc
@@ -37,7 +37,8 @@ AUAudioInputStream::AUAudioInputStream(
       audio_unit_(0),
       input_device_id_(audio_device_id),
       started_(false),
-      hardware_latency_frames_(0) {
+      hardware_latency_frames_(0),
+      number_of_channels_in_frame_(0) {
   DCHECK(manager_);
 
   // Set up the desired (output) format specified by the client.
@@ -211,6 +212,8 @@ bool AUAudioInputStream::Open() {
   // The hardware latency is fixed and will not change during the call.
   hardware_latency_frames_ = GetHardwareLatency();
 
+  number_of_channels_in_frame_ = GetNumberOfChannelsFromStream();

[henrika (OOO until Aug 14), 2012/02/21 14:03:47]

Why adding "FromStream()"?

[no longer working on chromium, 2012/02/21 18:01:38]

I want to make it more specific to differentiate this
number_of_channels_in_frame_ from the channel number in AudioParams, because
they can be different. For example, if we try to open the device in mono mode,
we can the number_of_channels_in_frame_ can still be 2. 

+
   return true;
 }
 
@@ -263,6 +266,138 @@ void AUAudioInputStream::Close() {
   manager_->ReleaseInputStream(this);
 }
 
+void AUAudioInputStream::SetMicVolume(double volume) {
+  DCHECK(volume <= 1.0 && volume >= 0.0);
+
+  // Verify that we have a valid device.
+  if (input_device_id_ == kAudioObjectUnknown)
+    return;
+
+  Float32 volume_float32 = static_cast<Float32> (volume);
+  AudioObjectPropertyAddress property_address = {
+    kAudioDevicePropertyVolumeScalar,
+    kAudioDevicePropertyScopeInput,
+    kAudioObjectPropertyElementMaster
+  };
+
+  // Try to set the volume for master volume channel.
+  if (IsVolumeSettableOnChannel(kAudioObjectPropertyElementMaster)) {
+    UInt32 size = sizeof(volume_float32);
+    OSStatus result = AudioObjectSetPropertyData(input_device_id_,
+                                                 &property_address,
+                                                 0,
+                                                 NULL,
+                                                 size,
+                                                 &volume_float32);
+    DLOG_IF(WARNING, result != noErr) << "SetMicVolume failed to set volume to "
+                                      << volume_float32;
+    return;
+  }
+
+  // There is no master volume control, try to set volume for each channel.

[henrika (OOO until Aug 14), 2012/02/21 14:03:47]

Can there be one master volume and channel volumes?

[no longer working on chromium, 2012/02/21 18:01:38]

If it supports master volume, we use master volume.

+  int success = 0;
+  for (UInt32 i = 1; i <= number_of_channels_in_frame_; i++) {
+    property_address.mElement = i;
+    if (IsVolumeSettableOnChannel(i)) {
+      UInt32 size = sizeof(volume_float32);
+      OSStatus result = AudioObjectSetPropertyData(input_device_id_,
+                                                   &property_address,
+                                                   0,
+                                                   NULL,
+                                                   size,
+                                                   &volume_float32);
+      if (result == noErr)
+        ++success;
+    }
+  }
+
+  DLOG_IF(WARNING, success == noErr) << "SetMicVolume failed to set volume to "
+                                     << volume_float32;
+}
+
+void AUAudioInputStream::GetMicVolume(double* volume) {
+  // Verify that we have a valid device.
+  if (input_device_id_ == kAudioObjectUnknown)
+    return;
+
+  *volume = 0.0;
+  AudioObjectPropertyAddress property_address = {
+    kAudioDevicePropertyVolumeScalar,
+    kAudioDevicePropertyScopeInput,
+    kAudioObjectPropertyElementMaster
+  };
+
+  if (AudioObjectHasProperty(input_device_id_, &property_address)) {
+    // The device supports master volume control, get the volume from the
+    // master channel.
+    Float32 volume_float32 = 0.0;
+    UInt32 size = sizeof(volume_float32);
+    OSStatus result = AudioObjectGetPropertyData(input_device_id_,
+                                                 &property_address,
+                                                 0,
+                                                 NULL,
+                                                 &size,
+                                                 &volume_float32);
+    if (result != noErr) {
+      DLOG(WARNING) << "AudioObjectGetPropertyData failed not get volume.";
+      return;
+    }
+    *volume = static_cast<double> (volume_float32);
+  } else {
+    // There is no master volume control, try to get the average volume of
+    // all the channels.
+    Float32 volume_float32 = 0.0;
+    int success = 0;

[henrika (OOO until Aug 14), 2012/02/21 14:03:47]

Not clear that this is a counter.

[no longer working on chromium, 2012/02/21 18:01:38]

Done.

+    for (UInt32 i = 1; i <= number_of_channels_in_frame_; i++) {
+      property_address.mElement = i;
+      if (AudioObjectHasProperty(input_device_id_, &property_address)) {
+        Float32 channel_volume = 0;
+        UInt32 size = sizeof(channel_volume);
+        OSStatus result = AudioObjectGetPropertyData(input_device_id_,
+                                                     &property_address,
+                                                     0,
+                                                     NULL,
+                                                     &size,
+                                                     &channel_volume);
+        if (result == noErr) {
+          volume_float32 += channel_volume;
+          ++success;
+        }
+      }
+    }
+    if (success == 0) {
+      DLOG(WARNING) << "Unable to get volume from any channel";
+      return;
+    }
+
+    // Get the average volume of the channels.
+    *volume = static_cast<double> (volume_float32 / success);
+  }
+}
+
+void AUAudioInputStream::GetMaxMicVolume(double* volume) {
+  // Verify that we have a valid device.
+  if (input_device_id_ == kAudioObjectUnknown)
+    return;
+
+  if (IsVolumeSettableOnChannel(0)) {
+    // If the volume is settable, the  valid volume range is [0.0, 1.0].
+    *volume = 1.0;
+    return;
+  }
+
+  // There is no master volume control, try to set volume for each channel.
+  for (UInt32 i = 1; i <= number_of_channels_in_frame_; i++) {
+    if (IsVolumeSettableOnChannel(i)) {
+      *volume = 1.0;
+      return;
+    }
+  }
+
+  // Volume control is not available for the audio stream.
+  *volume = 0.0;
+}
+
 // AUHAL AudioDeviceOutput unit callback
 OSStatus AUAudioInputStream::InputProc(void* user_data,
                                        AudioUnitRenderActionFlags* flags,
@@ -438,9 +573,43 @@ double AUAudioInputStream::GetCaptureLatency(
   return (delay_frames + hardware_latency_frames_);
 }
 
+UInt32 AUAudioInputStream::GetNumberOfChannelsFromStream() {

[henrika (OOO until Aug 14), 2012/02/21 14:03:47]

Why not the same APIs as in the audio manager for Mac?

[no longer working on chromium, 2012/02/21 18:01:38]

I explored a bit on the apple documentation. It seems the code in audio manager
is to get the channel numbers in the device, and the code here is getting the
channel number of a specific stream.
But it still not sure if if this kAudioDevicePropertyStreamFormat is obsolete or
not.

+  // Get the stream format, to be able to read the number of channels.
+  AudioObjectPropertyAddress property_address = {
+    kAudioDevicePropertyStreamFormat,
+    kAudioDevicePropertyScopeInput,
+    kAudioObjectPropertyElementMaster
+  };
+  AudioStreamBasicDescription stream_format;
+  UInt32 size = sizeof(stream_format);
+  OSStatus result = AudioObjectGetPropertyData(input_device_id_,
+                                               &property_address,
+                                               0,
+                                               NULL,
+                                               &size,
+                                               &stream_format);
+  DLOG_IF(WARNING, result != noErr) << "Could not get stream format.";
+
+  return stream_format.mChannelsPerFrame;
+}
+
 void AUAudioInputStream::HandleError(OSStatus err) {
   NOTREACHED() << "error " << GetMacOSStatusErrorString(err)
                << " (" << err << ")";
   if (sink_)
     sink_->OnError(this, static_cast<int>(err));
 }
+
+bool AUAudioInputStream::IsVolumeSettableOnChannel(int channel) {
+  Boolean is_settable = false;
+  AudioObjectPropertyAddress property_address = {
+    kAudioDevicePropertyVolumeScalar,
+    kAudioDevicePropertyScopeInput,
+    kAudioObjectPropertyElementMaster
+  };
+  property_address.mElement = channel;
+  OSStatus result = AudioObjectIsPropertySettable(input_device_id_,
+                                                  &property_address,
+                                                  &is_settable);
+  return (result == noErr)? is_settable : false;

[henrika (OOO until Aug 14), 2012/02/21 14:03:47]

Same nit again. Please use ") ? is_"

[no longer working on chromium, 2012/02/21 18:01:38]

Done.

+}