--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
@@ -1960,43 +1960,47 @@ public:
     , mTrackId(aTrack->GetInputTrackId())
     , mSource(mTrack->GetInputStream()->AsSourceStream())
     , mPlayedTicks(0)
     , mPrincipalHandle(PRINCIPAL_HANDLE_NONE)
     , mListening(false)
     , mMaybeTrackNeedsUnmute(true)
   {
     MOZ_RELEASE_ASSERT(mSource, "Must be used with a SourceMediaStream");
+  }
+
+  virtual ~GenericReceiveListener()
+  {
+    NS_ReleaseOnMainThreadSystemGroup(
+      "GenericReceiveListener::track_", mTrack.forget());
+  }
+
+  void AddTrackToSource(uint32_t aRate = 0)
+  {
+    MOZ_ASSERT((aRate != 0 && mTrack->AsAudioStreamTrack()) ||
+               mTrack->AsVideoStreamTrack());
 
     if (mTrack->AsAudioStreamTrack()) {
       mSource->AddAudioTrack(
-          mTrackId, mSource->GraphRate(), 0, new AudioSegment());
+          mTrackId, aRate, 0, new AudioSegment());
     } else if (mTrack->AsVideoStreamTrack()) {
       mSource->AddTrack(mTrackId, 0, new VideoSegment());
-    } else {
-      MOZ_ASSERT_UNREACHABLE("Unknown track type");
     }
     CSFLogDebug(
       LOGTAG,
       "GenericReceiveListener added %s track %d (%p) to stream %p",
       mTrack->AsAudioStreamTrack() ? "audio" : "video",
       mTrackId,
       mTrack.get(),
       mSource.get());
 
     mSource->AdvanceKnownTracksTime(STREAM_TIME_MAX);
     mSource->AddListener(this);
   }
 
-  virtual ~GenericReceiveListener()
-  {
-    NS_ReleaseOnMainThreadSystemGroup(
-      "GenericReceiveListener::track_", mTrack.forget());
-  }
-
   void AddSelf()
   {
     if (!mListening) {
       mListening = true;
       mSource->SetPullEnabled(true);
       mMaybeTrackNeedsUnmute = true;
     }
   }
@@ -2110,16 +2114,17 @@ public:
                 ->IsSamplingFreqSupported(mSource->GraphRate())
               ? mSource->GraphRate()
               : WEBRTC_MAX_SAMPLE_RATE)
     , mTaskQueue(
         new AutoTaskQueue(GetMediaThreadPool(MediaThreadType::WEBRTC_DECODER),
                           "AudioPipelineListener"))
     , mLastLog(0)
   {
+    AddTrackToSource(mRate);
   }
 
   // Implement MediaStreamListener
   void NotifyPull(MediaStreamGraph* aGraph,
                   StreamTime aDesiredTime) override
   {
     NotifyPullImpl(aDesiredTime);
   }
@@ -2141,20 +2146,23 @@ private:
   {
     NS_ReleaseOnMainThreadSystemGroup("MediaPipeline::mConduit",
                                       mConduit.forget());
   }
 
   void NotifyPullImpl(StreamTime aDesiredTime)
   {
     uint32_t samplesPer10ms = mRate / 100;
-    // Determine how many frames we need.
-    // As we get frames from conduit_ at the same rate as the graph's rate,
-    // the number of frames needed straightfully determined.
-    TrackTicks framesNeeded = aDesiredTime - mPlayedTicks;
+
+    // mSource's rate is not necessarily the same as the graph rate, since there
+    // are sample-rate constraints on the inbound audio: only 16, 32, 44.1 and
+    // 48kHz are supported. The audio frames we get here is going to be
+    // resampled when inserted into the graph.
+    TrackTicks desired = mSource->TimeToTicksRoundUp(mRate, aDesiredTime);
+    TrackTicks framesNeeded = desired - mPlayedTicks;
 
     while (framesNeeded >= 0) {
       const int scratchBufferLength =
         AUDIO_SAMPLE_BUFFER_MAX_BYTES / sizeof(int16_t);
       int16_t scratchBuffer[scratchBufferLength];
 
       int samplesLength = scratchBufferLength;
 
@@ -2308,16 +2316,17 @@ class MediaPipelineReceiveVideo::Pipelin
 {
 public:
   explicit PipelineListener(dom::MediaStreamTrack* aTrack)
     : GenericReceiveListener(aTrack)
     , mImageContainer(
         LayerManager::CreateImageContainer(ImageContainer::ASYNCHRONOUS))
     , mMutex("Video PipelineListener")
   {
+    AddTrackToSource();
   }
 
   // Implement MediaStreamListener
   void NotifyPull(MediaStreamGraph* aGraph, StreamTime aDesiredTime) override
   {
     MutexAutoLock lock(mMutex);
 
     RefPtr<Image> image = mImage;