Minor voice engine improvements around AGC.

- Remove one unneeded lock in CaptureLevel(), as the call to this
method should always come on the same thread as PrepareDemux().
- Remove check on analog AGC before doing volume calculations. Saves a
bit of code. Instead check if the incoming volume is set to zero, which
is a potentially common occurrence as it indicates no volume is
available.

R=aluebs@webrtc.org, xians@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/6859004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5366 4adac7df-926f-26a2-2b94-8c16560cd09d

1 files changed, 1 insertions, 3 deletions

diff --git a/voice_engine/transmit_mixer.cc b/voice_engine/transmit_mixer.cc
index b9618c81..e8b3365b 100644
--- a/voice_engine/transmit_mixer.cc
+++ b/voice_engine/transmit_mixer.cc
@@ -494,7 +494,6 @@ void TransmitMixer::EncodeAndSend(const int voe_channels[],
 
 uint32_t TransmitMixer::CaptureLevel() const
 {
-    CriticalSectionScoped cs(&_critSect);
     return _captureLevel;
 }
 
@@ -1341,11 +1340,10 @@ void TransmitMixer::ProcessAudio(int delay_ms, int clock_drift,
     assert(false);
   }
 
-  CriticalSectionScoped cs(&_critSect);
-
   // Store new capture level. Only updated when analog AGC is enabled.
   _captureLevel = agc->stream_analog_level();
 
+  CriticalSectionScoped cs(&_critSect);
   // Triggers a callback in OnPeriodicProcess().
   _saturationWarning |= agc->stream_is_saturated();
 }