diff --git a/extensions/flac/src/main/java/com/google/android/exoplayer/ext/flac/FlacDecoder.java b/extensions/flac/src/main/java/com/google/android/exoplayer/ext/flac/FlacDecoder.java
index 50a7c6bedd..d94d5cdad3 100644
--- a/extensions/flac/src/main/java/com/google/android/exoplayer/ext/flac/FlacDecoder.java
+++ b/extensions/flac/src/main/java/com/google/android/exoplayer/ext/flac/FlacDecoder.java
@@ -61,6 +61,11 @@ import java.util.List;
     maxOutputBufferSize = streamInfo.maxDecodedFrameSize();
   }
 
+  @Override
+  public String getName() {
+    return "libflac";
+  }
+
   @Override
   public DecoderInputBuffer createInputBuffer() {
     return new DecoderInputBuffer(DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_NORMAL);
diff --git a/extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/OpusDecoder.java b/extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/OpusDecoder.java
index 7490b763ba..8f5a70a7f5 100644
--- a/extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/OpusDecoder.java
+++ b/extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/OpusDecoder.java
@@ -132,6 +132,11 @@ import java.util.List;
     setInitialInputBufferSize(initialInputBufferSize);
   }
 
+  @Override
+  public String getName() {
+    return "libopus" + getLibopusVersion();
+  }
+
   @Override
   public DecoderInputBuffer createInputBuffer() {
     return new DecoderInputBuffer(DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_DIRECT);
diff --git a/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java b/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java
index 403ed47eda..670599908a 100644
--- a/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java
+++ b/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java
@@ -151,13 +151,15 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
     try {
       if (decoder == null) {
         // If we don't have a decoder yet, we need to instantiate one.
-        long startElapsedRealtimeMs = SystemClock.elapsedRealtime();
+        long codecInitializingTimestamp = SystemClock.elapsedRealtime();
         decoder = new VpxDecoder(NUM_BUFFERS, NUM_BUFFERS, INITIAL_INPUT_BUFFER_SIZE);
         decoder.setOutputMode(outputMode);
-        notifyDecoderInitialized(startElapsedRealtimeMs, SystemClock.elapsedRealtime());
+        long codecInitializedTimestamp = SystemClock.elapsedRealtime();
+        notifyDecoderInitialized(decoder.getName(), codecInitializedTimestamp,
+            codecInitializedTimestamp - codecInitializingTimestamp);
         codecCounters.codecInitCount++;
       }
-      while (processOutputBuffer(positionUs)) {}
+      while (drainOutputBuffer(positionUs)) {}
       while (feedInputBuffer()) {}
     } catch (VpxDecoderException e) {
       throw ExoPlaybackException.createForRenderer(e, getIndex());
@@ -165,8 +167,7 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
     codecCounters.ensureUpdated();
   }
 
-  private boolean processOutputBuffer(long positionUs)
-      throws VpxDecoderException {
+  private boolean drainOutputBuffer(long positionUs) throws VpxDecoderException {
     if (outputStreamEnded) {
       return false;
     }
@@ -226,7 +227,7 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
 
   private void renderBuffer() {
     codecCounters.renderedOutputBufferCount++;
-    notifyIfVideoSizeChanged(outputBuffer);
+    notifyIfVideoSizeChanged(outputBuffer.width, outputBuffer.height);
     if (outputBuffer.mode == VpxDecoder.OUTPUT_MODE_RGB && surface != null) {
       renderRgbFrame(outputBuffer, scaleToFit);
       if (!drawnToSurface) {
@@ -280,9 +281,13 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
     }
     if (inputBuffer.isEndOfStream()) {
       inputStreamEnded = true;
+      decoder.queueInputBuffer(inputBuffer);
+      inputBuffer = null;
+      return false;
     }
     inputBuffer.flip();
     decoder.queueInputBuffer(inputBuffer);
+    codecCounters.inputBufferCount++;
     inputBuffer = null;
     return true;
   }
@@ -398,16 +403,16 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
     }
   }
 
-  private void notifyIfVideoSizeChanged(final VpxOutputBuffer outputBuffer) {
-    if (previousWidth == -1 || previousHeight == -1
-        || previousWidth != outputBuffer.width || previousHeight != outputBuffer.height) {
-      previousWidth = outputBuffer.width;
-      previousHeight = outputBuffer.height;
+  private void notifyIfVideoSizeChanged(final int width, final int height) {
+    if (previousWidth == -1 || previousHeight == -1 || previousWidth != width
+        || previousHeight != height) {
+      previousWidth = width;
+      previousHeight = height;
       if (eventHandler != null && eventListener != null) {
         eventHandler.post(new Runnable()  {
           @Override
           public void run() {
-            eventListener.onVideoSizeChanged(outputBuffer.width, outputBuffer.height, 0, 1);
+            eventListener.onVideoSizeChanged(width, height, 0, 1);
           }
         });
       }
@@ -441,14 +446,14 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
     }
   }
 
-  private void notifyDecoderInitialized(
-      final long startElapsedRealtimeMs, final long finishElapsedRealtimeMs) {
+  private void notifyDecoderInitialized(final String decoderName,
+      final long initializedTimestamp, final long initializationDuration) {
     if (eventHandler != null && eventListener != null) {
       eventHandler.post(new Runnable() {
         @Override
         public void run() {
-          eventListener.onDecoderInitialized("libvpx" + getLibvpxVersion(),
-              finishElapsedRealtimeMs, finishElapsedRealtimeMs - startElapsedRealtimeMs);
+          eventListener.onDecoderInitialized(decoderName, initializedTimestamp,
+              initializationDuration);
         }
       });
     }
diff --git a/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/VpxDecoder.java b/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/VpxDecoder.java
index d5dfc3f0da..acaf6fc3a7 100644
--- a/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/VpxDecoder.java
+++ b/extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/VpxDecoder.java
@@ -74,6 +74,11 @@ import java.nio.ByteBuffer;
     setInitialInputBufferSize(initialInputBufferSize);
   }
 
+  @Override
+  public String getName() {
+    return "libvpx" + getLibvpxVersion();
+  }
+
   /**
    * Sets the output mode for frames rendered by the decoder.
    *
diff --git a/library/src/main/java/com/google/android/exoplayer/extensions/AudioDecoderTrackRenderer.java b/library/src/main/java/com/google/android/exoplayer/extensions/AudioDecoderTrackRenderer.java
index 679b0e2b9e..b4629ca03b 100644
--- a/library/src/main/java/com/google/android/exoplayer/extensions/AudioDecoderTrackRenderer.java
+++ b/library/src/main/java/com/google/android/exoplayer/extensions/AudioDecoderTrackRenderer.java
@@ -30,6 +30,7 @@ import com.google.android.exoplayer.audio.AudioTrack;
 import com.google.android.exoplayer.util.MimeTypes;
 
 import android.os.Handler;
+import android.os.SystemClock;
 
 /**
  * Decodes and renders audio using a {@link SimpleDecoder}.
@@ -63,6 +64,9 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
   private final AudioTrack audioTrack;
   private int audioSessionId;
 
+  private boolean audioTrackHasData;
+  private long lastFeedElapsedRealtimeMs;
+
   public AudioDecoderTrackRenderer() {
     this(null, null);
   }
@@ -101,16 +105,20 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
     // If we don't have a decoder yet, we need to instantiate one.
     if (decoder == null) {
       try {
+        long codecInitializingTimestamp = SystemClock.elapsedRealtime();
         decoder = createDecoder(inputFormat);
+        long codecInitializedTimestamp = SystemClock.elapsedRealtime();
+        notifyDecoderInitialized(decoder.getName(), codecInitializedTimestamp,
+            codecInitializedTimestamp - codecInitializingTimestamp);
+        codecCounters.codecInitCount++;
       } catch (AudioDecoderException e) {
         throw ExoPlaybackException.createForRenderer(e, getIndex());
       }
-      codecCounters.codecInitCount++;
     }
 
     // Rendering loop.
     try {
-      renderBuffer();
+      while (drainOutputBuffer()) {}
       while (feedInputBuffer()) {}
     } catch (AudioTrack.InitializationException e) {
       notifyAudioTrackInitializationError(e);
@@ -145,16 +153,16 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
         null, null, null);
   }
 
-  private void renderBuffer() throws AudioDecoderException, AudioTrack.InitializationException,
-      AudioTrack.WriteException {
+  private boolean drainOutputBuffer() throws AudioDecoderException,
+      AudioTrack.InitializationException, AudioTrack.WriteException {
     if (outputStreamEnded) {
-      return;
+      return false;
     }
 
     if (outputBuffer == null) {
       outputBuffer = decoder.dequeueOutputBuffer();
       if (outputBuffer == null) {
-        return;
+        return false;
       }
     }
 
@@ -163,7 +171,7 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
       audioTrack.handleEndOfStream();
       outputBuffer.release();
       outputBuffer = null;
-      return;
+      return false;
     }
 
     if (!audioTrack.isInitialized()) {
@@ -174,14 +182,26 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
         audioTrack.initialize(audioSessionId);
       } else {
         audioSessionId = audioTrack.initialize();
+        onAudioSessionId(audioSessionId);
       }
+      audioTrackHasData = false;
       if (getState() == TrackRenderer.STATE_STARTED) {
         audioTrack.play();
       }
+    } else {
+      // Check for AudioTrack underrun.
+      boolean audioTrackHadData = audioTrackHasData;
+      audioTrackHasData = audioTrack.hasPendingData();
+      if (audioTrackHadData && !audioTrackHasData && getState() == TrackRenderer.STATE_STARTED) {
+        long elapsedSinceLastFeedMs = SystemClock.elapsedRealtime() - lastFeedElapsedRealtimeMs;
+        long bufferSizeUs = audioTrack.getBufferSizeUs();
+        long bufferSizeMs = bufferSizeUs == C.UNSET_TIME_US ? -1 : bufferSizeUs / 1000;
+        notifyAudioTrackUnderrun(audioTrack.getBufferSize(), bufferSizeMs, elapsedSinceLastFeedMs);
+      }
     }
 
-    int handleBufferResult;
-    handleBufferResult = audioTrack.handleBuffer(outputBuffer.data, outputBuffer.timestampUs);
+    int handleBufferResult = audioTrack.handleBuffer(outputBuffer.data, outputBuffer.timestampUs);
+    lastFeedElapsedRealtimeMs = SystemClock.elapsedRealtime();
 
     // If we are out of sync, allow currentPositionUs to jump backwards.
     if ((handleBufferResult & AudioTrack.RESULT_POSITION_DISCONTINUITY) != 0) {
@@ -193,7 +213,10 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
       codecCounters.renderedOutputBufferCount++;
       outputBuffer.release();
       outputBuffer = null;
+      return true;
     }
+
+    return false;
   }
 
   private boolean feedInputBuffer() throws AudioDecoderException {
@@ -218,10 +241,13 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
     }
     if (inputBuffer.isEndOfStream()) {
       inputStreamEnded = true;
+      decoder.queueInputBuffer(inputBuffer);
+      inputBuffer = null;
+      return false;
     }
-
     inputBuffer.flip();
     decoder.queueInputBuffer(inputBuffer);
+    codecCounters.inputBufferCount++;
     inputBuffer = null;
     return true;
   }
@@ -269,6 +295,19 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
     }
   }
 
+  /**
+   * Invoked when the audio session id becomes known. Once the id is known it will not change
+   * (and hence this method will not be invoked again) unless the renderer is disabled and then
+   * subsequently re-enabled.
+   * <p>
+   * The default implementation is a no-op.
+   *
+   * @param audioSessionId The audio session id.
+   */
+  protected void onAudioSessionId(int audioSessionId) {
+    // Do nothing.
+  }
+
   @Override
   protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
     notifyAudioCodecCounters();
@@ -320,6 +359,19 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
     }
   }
 
+  private void notifyDecoderInitialized(final String decoderName,
+      final long initializedTimestamp, final long initializationDuration) {
+    if (eventHandler != null && eventListener != null) {
+      eventHandler.post(new Runnable() {
+        @Override
+        public void run() {
+          eventListener.onDecoderInitialized(decoderName, initializedTimestamp,
+              initializationDuration);
+        }
+      });
+    }
+  }
+
   private void notifyAudioTrackInitializationError(final AudioTrack.InitializationException e) {
     if (eventHandler != null && eventListener != null) {
       eventHandler.post(new Runnable() {
@@ -342,6 +394,18 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
     }
   }
 
+  private void notifyAudioTrackUnderrun(final int bufferSize, final long bufferSizeMs,
+      final long elapsedSinceLastFeedMs) {
+    if (eventHandler != null && eventListener != null) {
+      eventHandler.post(new Runnable()  {
+        @Override
+        public void run() {
+          eventListener.onAudioTrackUnderrun(bufferSize, bufferSizeMs, elapsedSinceLastFeedMs);
+        }
+      });
+    }
+  }
+
   private void notifyAudioCodecCounters() {
     if (eventHandler != null && eventListener != null) {
       eventHandler.post(new Runnable() {
diff --git a/library/src/main/java/com/google/android/exoplayer/extensions/Decoder.java b/library/src/main/java/com/google/android/exoplayer/extensions/Decoder.java
index 4d0218c328..38eb4f07f5 100644
--- a/library/src/main/java/com/google/android/exoplayer/extensions/Decoder.java
+++ b/library/src/main/java/com/google/android/exoplayer/extensions/Decoder.java
@@ -24,6 +24,13 @@ package com.google.android.exoplayer.extensions;
  */
 public interface Decoder<I, O, E extends Exception> {
 
+  /**
+   * Returns the name of the decoder.
+   *
+   * @return The name of the decoder.
+   */
+  String getName();
+
   /**
    * Dequeues the next input buffer to be filled and queued to the decoder.
    *
diff --git a/library/src/main/java/com/google/android/exoplayer/text/SimpleSubtitleParser.java b/library/src/main/java/com/google/android/exoplayer/text/SimpleSubtitleParser.java
index b8dd1106d4..5dbfc37058 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/SimpleSubtitleParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/SimpleSubtitleParser.java
@@ -27,11 +27,19 @@ public abstract class SimpleSubtitleParser extends
     SimpleDecoder<SubtitleInputBuffer, SubtitleOutputBuffer, ParserException> implements
     SubtitleParser {
 
-  protected SimpleSubtitleParser() {
+  private final String name;
+
+  protected SimpleSubtitleParser(String name) {
     super(new SubtitleInputBuffer[2], new SubtitleOutputBuffer[2]);
+    this.name = name;
     setInitialInputBufferSize(1024);
   }
 
+  @Override
+  public final String getName() {
+    return name;
+  }
+
   @Override
   public void setPositionUs(long timeUs) {
     // Do nothing
diff --git a/library/src/main/java/com/google/android/exoplayer/text/eia608/Eia608Parser.java b/library/src/main/java/com/google/android/exoplayer/text/eia608/Eia608Parser.java
index 7c0bb83b08..db1ea3373f 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/eia608/Eia608Parser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/eia608/Eia608Parser.java
@@ -205,6 +205,11 @@ public final class Eia608Parser implements SubtitleParser {
     captionRowCount = DEFAULT_CAPTIONS_ROW_COUNT;
   }
 
+  @Override
+  public String getName() {
+    return "Eia608Parser";
+  }
+
   @Override
   public void setPositionUs(long positionUs) {
     playbackPositionUs = positionUs;
diff --git a/library/src/main/java/com/google/android/exoplayer/text/subrip/SubripParser.java b/library/src/main/java/com/google/android/exoplayer/text/subrip/SubripParser.java
index f39d49b5f4..9e752deb3d 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/subrip/SubripParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/subrip/SubripParser.java
@@ -43,6 +43,7 @@ public final class SubripParser extends SimpleSubtitleParser {
   private final StringBuilder textBuilder;
 
   public SubripParser() {
+    super("SubripParser");
     textBuilder = new StringBuilder();
   }
 
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
index e0907d0364..527bd533ae 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
@@ -87,6 +87,7 @@ public final class TtmlParser extends SimpleSubtitleParser {
   private final XmlPullParserFactory xmlParserFactory;
 
   public TtmlParser() {
+    super("TtmlParser");
     try {
       xmlParserFactory = XmlPullParserFactory.newInstance();
       xmlParserFactory.setNamespaceAware(true);
diff --git a/library/src/main/java/com/google/android/exoplayer/text/tx3g/Tx3gParser.java b/library/src/main/java/com/google/android/exoplayer/text/tx3g/Tx3gParser.java
index b2259ab085..f6a1436940 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/tx3g/Tx3gParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/tx3g/Tx3gParser.java
@@ -26,6 +26,10 @@ import com.google.android.exoplayer.text.Subtitle;
  */
 public final class Tx3gParser extends SimpleSubtitleParser {
 
+  public Tx3gParser() {
+    super("Tx3gParser");
+  }
+
   @Override
   protected Subtitle decode(byte[] bytes, int length) {
     String cueText = new String(bytes, 0, length);
diff --git a/library/src/main/java/com/google/android/exoplayer/text/webvtt/Mp4WebvttParser.java b/library/src/main/java/com/google/android/exoplayer/text/webvtt/Mp4WebvttParser.java
index 82da06ae84..1690507961 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/webvtt/Mp4WebvttParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/webvtt/Mp4WebvttParser.java
@@ -40,6 +40,7 @@ public final class Mp4WebvttParser extends SimpleSubtitleParser {
   private final WebvttCue.Builder builder;
 
   public Mp4WebvttParser() {
+    super("Mp4WebvttParser");
     sampleData = new ParsableByteArray();
     builder = new WebvttCue.Builder();
   }
diff --git a/library/src/main/java/com/google/android/exoplayer/text/webvtt/WebvttParser.java b/library/src/main/java/com/google/android/exoplayer/text/webvtt/WebvttParser.java
index 6dfd59d7f4..dd0e7337d2 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/webvtt/WebvttParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/webvtt/WebvttParser.java
@@ -46,6 +46,7 @@ public final class WebvttParser extends SimpleSubtitleParser {
   private final List<WebvttCssStyle> definedStyles;
 
   public WebvttParser() {
+    super("WebvttParser");
     cueParser = new WebvttCueParser();
     parsableWebvttData = new ParsableByteArray();
     webvttCueBuilder = new WebvttCue.Builder();