Check the mic volume only periodically on Mac.

webrtc/modules/audio_device/mac/audio_device_mac.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 131 matching lines @@
     _renderDelayOffsetSamples(0),
     _playBufDelayFixed(20),
     _playWarning(0),
     _playError(0),
     _recWarning(0),
     _recError(0),
     _paCaptureBuffer(NULL),
     _paRenderBuffer(NULL),
     _captureBufSizeSamples(0),
     _renderBufSizeSamples(0),
-    prev_key_state_()
+    prev_key_state_(),
+    get_mic_volume_counter_ms_(0)
 {
     WEBRTC_TRACE(kTraceMemory, kTraceAudioDevice, id,
                  "%s created", __FUNCTION__);
 
     RTC_DCHECK(&_stopEvent != NULL);
     RTC_DCHECK(&_stopEventRec != NULL);
 
     memset(_renderConvertData, 0, sizeof(_renderConvertData));
     memset(&_outStreamFormat, 0, sizeof(AudioStreamBasicDescription));
     memset(&_outDesiredFormat, 0, sizeof(AudioStreamBasicDescription));
@@ skipping 209 matching lines @@
         {
             _macBookPro = true;
         }
     }
 
     _playWarning = 0;
     _playError = 0;
     _recWarning = 0;
     _recError = 0;
 
+    get_mic_volume_counter_ms_ = 0;
+
     _initialized = true;
 
     return 0;
 }
 
 int32_t AudioDeviceMac::Terminate()
 {
 
     if (!_initialized)
     {
@@ skipping 2782 matching lines @@
             return false;
         }
 
         // store the recorded buffer (no action will be taken if the
         // #recorded samples is not a full buffer)
         _ptrAudioBuffer->SetRecordedBuffer((int8_t*) &recordBuffer,
                                            (uint32_t) size);
 
         if (AGC())
         {
-            // store current mic level in the audio buffer if AGC is enabled
-            if (MicrophoneVolume(currentMicLevel) == 0)
-            {
-                // this call does not affect the actual microphone volume
-                _ptrAudioBuffer->SetCurrentMicLevel(currentMicLevel);
+            // Use mod to ensure we check the volume on the first pass.

[henrika_webrtc, 2016/01/08 08:14:42]

Out indentation kind of sucks but I guess we should change it in the complete
file and not just where we make changes. Just an idea.

[Andrew MacDonald, 2016/01/08 08:22:09]

:)

I can run clang-format on these files in a follow-up CL.

+            if (get_mic_volume_counter_ms_ % kGetMicVolumeIntervalMs == 0) {
+                get_mic_volume_counter_ms_ = 0;
+                // store current mic level in the audio buffer if AGC is enabled
+                if (MicrophoneVolume(currentMicLevel) == 0)
+                {
+                    // this call does not affect the actual microphone volume
+                    _ptrAudioBuffer->SetCurrentMicLevel(currentMicLevel);
+                }
             }
+            get_mic_volume_counter_ms_ += kBufferSizeMs;
         }
 
         _ptrAudioBuffer->SetVQEData(msecOnPlaySide, msecOnRecordSide, 0);
 
         _ptrAudioBuffer->SetTypingStatus(KeyPressed());
 
         // deliver recorded samples at specified sample rate, mic level etc.
         // to the observer using callback
         _ptrAudioBuffer->DeliverRecordedData();
 
@@ skipping 32 matching lines @@
                              kCGEventSourceStateHIDSystemState,
                              key_index);
     // A false -> true change in keymap means a key is pressed.
     key_down |= (keyState && !prev_key_state_[key_index]);
     // Save current state.
     prev_key_state_[key_index] = keyState;
   }
   return key_down;
 }
 }  // namespace webrtc