diff --git a/dom/media/GraphDriver.cpp b/dom/media/GraphDriver.cpp
index 4a4ec136ecfa..4f2fa76a74b7 100644
--- a/dom/media/GraphDriver.cpp
+++ b/dom/media/GraphDriver.cpp
@@ -662,19 +662,10 @@ AudioCallbackDriver::Init()
     latency_frames = std::max((uint32_t) 512, latency_frames);
   }
 
-  input = output;
-  input.channels = mInputChannels;
-  input.layout = CUBEB_LAYOUT_UNDEFINED;
 
-#ifdef MOZ_WEBRTC
-  if (mGraphImpl->mInputWanted) {
-    StaticMutexAutoLock lock(AudioInputCubeb::Mutex());
-    uint32_t maxInputChannels = 0;
-    if (AudioInputCubeb::GetDeviceMaxChannels(mGraphImpl->mInputDeviceID, maxInputChannels) == 0) {
-      input.channels = mInputChannels = maxInputChannels;
-    }
-  }
-#endif
+  input = output;
+  input.channels = mInputChannels; // change to support optional stereo capture
+  input.layout = CUBEB_LAYOUT_MONO;
 
   cubeb_stream* stream = nullptr;
   CubebUtils::AudioDeviceID input_id = nullptr, output_id = nullptr;
diff --git a/dom/media/webrtc/MediaEngineWebRTC.h b/dom/media/webrtc/MediaEngineWebRTC.h
index 83105d177634..d82e6cc5ba7d 100644
--- a/dom/media/webrtc/MediaEngineWebRTC.h
+++ b/dom/media/webrtc/MediaEngineWebRTC.h
@@ -212,7 +212,6 @@ public:
         aIndex = mDefaultDevice;
       }
     }
-    MOZ_ASSERT(mDeviceIndexes);
     if (aIndex < 0 || aIndex >= (int) mDeviceIndexes->Length()) {
       return -1;
     }
@@ -268,20 +267,6 @@ public:
     return 0;
   }
 
-  static int GetDeviceMaxChannels(int aDeviceIndex, uint32_t& aChannels)
-  {
-#ifdef MOZ_WIDGET_ANDROID
-    aChannels = 1;
-#else
-    int32_t devindex = DeviceIndex(aDeviceIndex);
-    if (!mDevices || devindex < 0) {
-      return 1;
-    }
-    aChannels = mDevices->device[devindex]->max_channels;
-#endif
-    return 0;
-  }
-
   void StartRecording(SourceMediaStream *aStream, AudioDataListener *aListener)
   {
 #ifdef MOZ_WIDGET_ANDROID