Adds Analog Gain Control (AGC) to the WebRTC client.

media/audio/audio_input_controller.cc

Index: media/audio/audio_input_controller.cc
diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index 14d3bbae0e86f267d74f3dc10c1cbd26d6192eda..cef502e716483803579db5b6597e50d04cb1111e 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -28,7 +28,8 @@ AudioInputController::AudioInputController(EventHandler* handler,
           this,
           &AudioInputController::DoReportNoDataError)),
       state_(kEmpty),
-      sync_writer_(sync_writer) {
+      sync_writer_(sync_writer),
+      max_volume_(0.0) {
   DCHECK(creator_loop_);
 }
 
@@ -107,6 +108,16 @@ void AudioInputController::Close(const base::Closure& closed_task) {
       &AudioInputController::DoClose, this, closed_task));
 }
 
+void AudioInputController::SetVolume(double volume) {
+  message_loop_->PostTask(FROM_HERE, base::Bind(
+      &AudioInputController::DoSetVolume, this, volume));
+}
+
+void AudioInputController::SetAutomaticGainControl(bool enabled) {
+  message_loop_->PostTask(FROM_HERE, base::Bind(
+      &AudioInputController::DoSetAutomaticGainControl, this, enabled));
+}
+
 void AudioInputController::DoCreate(AudioManager* audio_manager,
                                     const AudioParameters& params,
                                     const std::string& device_id) {
@@ -171,6 +182,37 @@ void AudioInputController::DoReportError(int code) {
   handler_->OnError(this, code);
 }
 
+void AudioInputController::DoSetVolume(double volume) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  DCHECK(volume >= 0 && volume <= 1.0);

[scherkus (not reviewing), 2012/03/20 13:49:41]

nit: if you split these DCHECKs into DCHECK_GE() and DCHECK_LE() you'll get the
incorrect value reported on the console

[henrika (OOO until Aug 14), 2012/03/21 10:16:04]

Nice. Thanks.

+
+  if (state_ != kCreated && state_ != kRecording)
+    return;
+
+  // Only ask for the maximum volume at first call and use cached value
+  // for remaining function calls.
+  if (!max_volume_) {
+    max_volume_ = stream_->GetMaxVolume();
+  }
+
+  if (max_volume_ == 0.0) {
+    DLOG(WARNING) << "Failed to access input volume control";
+    return;
+  }
+
+  // Set the stream volume and scale to a range matched to the platform.
+  stream_->SetVolume(max_volume_ * volume);
+}
+
+void AudioInputController::DoSetAutomaticGainControl(bool enabled) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  if (state_ != kCreated)
+    return;
+
+  stream_->SetAutomaticGainControl(enabled);
+}
+
 void AudioInputController::DoReportNoDataError() {
   DCHECK(creator_loop_->BelongsToCurrentThread());
 
@@ -186,19 +228,20 @@ void AudioInputController::DoResetNoDataTimer() {
 }
 
 void AudioInputController::OnData(AudioInputStream* stream, const uint8* data,
-                                  uint32 size, uint32 hardware_delay_bytes) {
+                                  uint32 size, uint32 hardware_delay_bytes,
+                                  double volume) {
   {
     base::AutoLock auto_lock(lock_);
     if (state_ != kRecording)
       return;
   }
 
-  creator_loop_->PostTask(FROM_HERE, base::Bind(
+  creator_loop_->PostTask(FROM_HERE, base::Bind(
       &AudioInputController::DoResetNoDataTimer, this));
 
   // Use SyncSocket if we are in a low-latency mode.
   if (LowLatencyMode()) {
-    sync_writer_->Write(data, size);
+    sync_writer_->Write(data, size, volume);
     sync_writer_->UpdateRecordedBytes(hardware_delay_bytes);
     return;
   }