diff --git a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
index 26ba34a11aad..1c9b5c6c6d32 100644
--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
@@ -827,6 +827,13 @@ void MediaPipelineTransmit::PipelineListener::ProcessVideoChunk(
     return;
   }
 
+  // We get passed duplicate frames every ~10ms even if there's no frame change!
+  int32_t serial = img->GetSerial();
+  if (serial == last_img_) {
+    return;
+  }
+  last_img_ = serial;
+
   ImageFormat format = img->GetFormat();
 #ifdef MOZ_WIDGET_GONK
   if (format == GONK_IO_SURFACE) {
diff --git a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
index 46376227fbc6..52c3a312a90a 100644
--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
@@ -321,8 +321,12 @@ class MediaPipelineTransmit : public MediaPipeline {
   class PipelineListener : public MediaStreamListener {
    public:
     PipelineListener(const RefPtr<MediaSessionConduit>& conduit)
-      : conduit_(conduit), active_(false), samples_10ms_buffer_(nullptr),
-        buffer_current_(0), samplenum_10ms_(0){}
+      : conduit_(conduit),
+        active_(false),
+        last_img_(-1),
+        samples_10ms_buffer_(nullptr),
+        buffer_current_(0),
+        samplenum_10ms_(0) {}
 
     ~PipelineListener()
     {
@@ -359,6 +363,8 @@ class MediaPipelineTransmit : public MediaPipeline {
     RefPtr<MediaSessionConduit> conduit_;
     volatile bool active_;
 
+    int32_t last_img_; // serial number of last Image
+
     // These vars handle breaking audio samples into exact 10ms chunks:
     // The buffer of 10ms audio samples that we will send once full
     // (can be carried over from one call to another).