--- a/dom/media/encoder/TrackEncoder.cpp
+++ b/dom/media/encoder/TrackEncoder.cpp
@@ -40,74 +40,89 @@ TrackEncoder::TrackEncoder()
 void TrackEncoder::NotifyEvent(MediaStreamGraph* aGraph,
                  MediaStreamGraphEvent event)
 {
   if (event == MediaStreamGraphEvent::EVENT_REMOVED) {
     NotifyEndOfStream();
   }
 }
 
+nsresult
+AudioTrackEncoder::TryInit(const AudioSegment& aSegment, int aSamplingRate)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  if (mInitialized) {
+    return NS_OK;
+  }
+
+  mInitCounter++;
+  TRACK_LOG(LogLevel::Debug, ("Init the audio encoder %d times", mInitCounter));
+  AudioSegment::ConstChunkIterator iter(aSegment);
+  while (!iter.IsEnded()) {
+    AudioChunk chunk = *iter;
+
+    // The number of channels is determined by the first non-null chunk, and
+    // thus the audio encoder is initialized at this time.
+    if (!chunk.IsNull()) {
+      nsresult rv = Init(chunk.mChannelData.Length(), aSamplingRate);
+      if (NS_FAILED(rv)) {
+        TRACK_LOG(LogLevel::Error,
+                  ("[AudioTrackEncoder]: Fail to initialize the encoder!"));
+        NotifyCancel();
+        return rv;
+      }
+      break;
+    }
+
+    iter.Next();
+  }
+
+  mNotInitDuration += aSegment.GetDuration();
+  if (!mInitialized &&
+      (mNotInitDuration / aSamplingRate >= AUDIO_INIT_FAILED_DURATION) &&
+      mInitCounter > 1) {
+    // Perform a best effort initialization since we haven't gotten any
+    // data yet. Motivated by issues like Bug 1336367
+    TRACK_LOG(LogLevel::Warning,
+              ("[AudioTrackEncoder]: Initialize failed "
+               "for %ds. Attempting to init with %d "
+               "(default) channels!",
+               AUDIO_INIT_FAILED_DURATION,
+               DEFAULT_CHANNELS));
+    nsresult rv = Init(DEFAULT_CHANNELS, aSamplingRate);
+    if (NS_FAILED(rv)) {
+      TRACK_LOG(LogLevel::Error,
+                ("[AudioTrackEncoder]: Fail to initialize the encoder!"));
+      NotifyCancel();
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
 void
 AudioTrackEncoder::NotifyQueuedTrackChanges(MediaStreamGraph* aGraph,
                                             TrackID aID,
                                             StreamTime aTrackOffset,
                                             uint32_t aTrackEvents,
                                             const MediaSegment& aQueuedMedia)
 {
   ReentrantMonitorAutoEnter mon(mReentrantMonitor);
 
   if (mCanceled) {
     return;
   }
 
   const AudioSegment& audio = static_cast<const AudioSegment&>(aQueuedMedia);
 
-  // Check and initialize parameters for codec encoder.
-  if (!mInitialized) {
-    mInitCounter++;
-    TRACK_LOG(LogLevel::Debug, ("Init the audio encoder %d times", mInitCounter));
-    AudioSegment::ChunkIterator iter(const_cast<AudioSegment&>(audio));
-    while (!iter.IsEnded()) {
-      AudioChunk chunk = *iter;
-
-      // The number of channels is determined by the first non-null chunk, and
-      // thus the audio encoder is initialized at this time.
-      if (!chunk.IsNull()) {
-        nsresult rv = Init(chunk.mChannelData.Length(), aGraph->GraphRate());
-        if (NS_FAILED(rv)) {
-          TRACK_LOG(LogLevel::Error, ("[AudioTrackEncoder]: Fail to initialize the encoder!"));
-          NotifyCancel();
-        }
-        break;
-      }
-
-      iter.Next();
-    }
-
-    mNotInitDuration += aQueuedMedia.GetDuration();
-    if (!mInitialized &&
-        (mNotInitDuration / aGraph->GraphRate() >=
-         AUDIO_INIT_FAILED_DURATION) &&
-        mInitCounter > 1) {
-      // Perform a best effort initialization since we haven't gotten any
-      // data yet. Motivated by issues like Bug 1336367
-      TRACK_LOG(LogLevel::Warning,
-                ("[AudioTrackEncoder]: Initialize failed "
-                 "for %ds. Attempting to init with %d "
-                 "(default) channels!",
-                 AUDIO_INIT_FAILED_DURATION,
-                 DEFAULT_CHANNELS));
-      nsresult rv = Init(DEFAULT_CHANNELS, aGraph->GraphRate());
-      if (NS_FAILED(rv)) {
-        TRACK_LOG(LogLevel::Error,
-                  ("[AudioTrackEncoder]: Fail to initialize the encoder!"));
-        NotifyCancel();
-        return;
-      }
-    }
+  nsresult rv = TryInit(audio, aGraph->GraphRate());
+  if (NS_FAILED(rv)) {
+    return;
   }
 
   // Append and consume this raw segment.
   AppendAudioSegment(audio);
 
 
   // The stream has stopped and reached the end of track.
   if (aTrackEvents == TrackEventCommand::TRACK_EVENT_ENDED) {

--- a/dom/media/encoder/TrackEncoder.h
+++ b/dom/media/encoder/TrackEncoder.h
@@ -197,16 +197,31 @@ protected:
   /**
    * Number of samples per channel in a pcm buffer. This is also the value of
    * frame size required by audio encoder, and mReentrantMonitor will be
    * notified when at least this much data has been added to mRawSegment.
    */
   virtual int GetPacketDuration() { return 0; }
 
   /**
+   * Attempt to initialize the audio encoder. The call of this method is
+   * delayed until we have received the first valid track from
+   * MediaStreamGraph, and the mReentrantMonitor will be notified if other
+   * methods is waiting for encoder to be completely initialized. This method
+   * is called on the MediaStreamGraph thread. This method will attempt to
+   * initialize with best effort if all the following are met:
+   * - it has been called multiple times
+   * - reached a threshold duration of audio data
+   * - the encoder has not yet initialized.
+   * Returns NS_OK on init, as well as when deferring for more data, so check
+   * mInitialized after calling as necessary.
+   */
+  virtual nsresult TryInit(const AudioSegment& aSegment, int aSamplingRate);
+
+  /**
    * Initializes the audio encoder. The call of this method is delayed until we
    * have received the first valid track from MediaStreamGraph, and the
    * mReentrantMonitor will be notified if other methods is waiting for encoder
    * to be completely initialized. This method is called on the MediaStreamGraph
    * thread.
    */
   virtual nsresult Init(int aChannels, int aSamplingRate) = 0;