Factor out position tracking from DefaultAudioSink

DefaultAudioSink had a lot of code related to tracking the position of the
underlying AudioTrack, and working around issues with the position APIs.

Move this code to a separate class responsible for position tracking. This is in
preparation for improving the audio timestamp polling behavior.

This change is intended not to cause any behavior changes.

Issue: #3841

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189344743

RELEASENOTES.md

@@ -21,6 +21,7 @@
     deprecated `DynamicConcatenatingMediaSource`.
   * Allow clipping of child media sources where the period and window have a
     non-zero offset with `ClippingMediaSource`.
+* Audio: Factor out `AudioTrack` position tracking from `DefaultAudioSink`.
 
 ### 2.7.1 ###
 

library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java

@@ -0,0 +1,609 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.audio;
+
+import android.annotation.TargetApi;
+import android.media.AudioTimestamp;
+import android.media.AudioTrack;
+import android.os.SystemClock;
+import android.support.annotation.IntDef;
+import android.support.annotation.Nullable;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Util;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.Method;
+
+/**
+ * Wraps an {@link AudioTrack}, exposing a position based on {@link
+ * AudioTrack#getPlaybackHeadPosition()} and {@link AudioTrack#getTimestamp(AudioTimestamp)}.
+ *
+ * <p>Call {@link #setAudioTrack(AudioTrack, int, int, int)} to set the audio track to wrap. Call
+ * {@link #mayHandleBuffer(long)} if there is input data to write to the track. If it returns false,
+ * the audio track position is stabilizing and no data may be written. Call {@link #start()}
+ * immediately before calling {@link AudioTrack#play()}. Call {@link #pause()} when pausing the
+ * track. Call {@link #handleEndOfStream(long)} when no more data will be written to the track. When
+ * the audio track will no longer be used, call {@link #reset()}.
+ */
+/* package */ final class AudioTrackPositionTracker {
+
+  /** Listener for position tracker events. */
+  public interface Listener {
+
+    /**
+     * Called when the frame position is too far from the expected frame position.
+     *
+     * @param audioTimestampPositionFrames The frame position of the last known audio track
+     *     timestamp.
+     * @param audioTimestampSystemTimeUs The system time associated with the last known audio track
+     *     timestamp, in microseconds.
+     * @param systemTimeUs The current time.
+     * @param playbackPositionUs The current playback head position in microseconds.
+     */
+    void onPositionFramesMismatch(
+        long audioTimestampPositionFrames,
+        long audioTimestampSystemTimeUs,
+        long systemTimeUs,
+        long playbackPositionUs);
+
+    /**
+     * Called when the system time associated with the last known audio track timestamp is
+     * unexpectedly far from the current time.
+     *
+     * @param audioTimestampPositionFrames The frame position of the last known audio track
+     *     timestamp.
+     * @param audioTimestampSystemTimeUs The system time associated with the last known audio track
+     *     timestamp, in microseconds.
+     * @param systemTimeUs The current time.
+     * @param playbackPositionUs The current playback head position in microseconds.
+     */
+    void onSystemTimeUsMismatch(
+        long audioTimestampPositionFrames,
+        long audioTimestampSystemTimeUs,
+        long systemTimeUs,
+        long playbackPositionUs);
+
+    /**
+     * Called when the audio track has provided an invalid latency.
+     *
+     * @param latencyUs The reported latency in microseconds.
+     */
+    void onInvalidLatency(long latencyUs);
+
+    /**
+     * Called when the audio track runs out of data to play.
+     *
+     * @param bufferSize The size of the sink's buffer, in bytes.
+     * @param bufferSizeMs The size of the sink's buffer, in milliseconds, if it is configured for
+     *     PCM output. {@link C#TIME_UNSET} if it is configured for encoded audio output, as the
+     *     buffered media can have a variable bitrate so the duration may be unknown.
+     */
+    void onUnderrun(int bufferSize, long bufferSizeMs);
+  }
+
+  /** {@link AudioTrack} playback states. */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({PLAYSTATE_STOPPED, PLAYSTATE_PAUSED, PLAYSTATE_PLAYING})
+  private @interface PlayState {}
+  /** @see AudioTrack#PLAYSTATE_STOPPED */
+  private static final int PLAYSTATE_STOPPED = AudioTrack.PLAYSTATE_STOPPED;
+  /** @see AudioTrack#PLAYSTATE_PAUSED */
+  private static final int PLAYSTATE_PAUSED = AudioTrack.PLAYSTATE_PAUSED;
+  /** @see AudioTrack#PLAYSTATE_PLAYING */
+  private static final int PLAYSTATE_PLAYING = AudioTrack.PLAYSTATE_PLAYING;
+
+  /**
+   * AudioTrack timestamps are deemed spurious if they are offset from the system clock by more than
+   * this amount.
+   *
+   * <p>This is a fail safe that should not be required on correctly functioning devices.
+   */
+  private static final long MAX_AUDIO_TIMESTAMP_OFFSET_US = 5 * C.MICROS_PER_SECOND;
+
+  /**
+   * AudioTrack latencies are deemed impossibly large if they are greater than this amount.
+   *
+   * <p>This is a fail safe that should not be required on correctly functioning devices.
+   */
+  private static final long MAX_LATENCY_US = 5 * C.MICROS_PER_SECOND;
+
+  private static final long FORCE_RESET_WORKAROUND_TIMEOUT_MS = 200;
+
+  private static final int MAX_PLAYHEAD_OFFSET_COUNT = 10;
+  private static final int MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US = 30000;
+  private static final int MIN_TIMESTAMP_SAMPLE_INTERVAL_US = 500000;
+  private static final int MIN_LATENCY_SAMPLE_INTERVAL_US = 500000;
+
+  private final Listener listener;
+  private final long[] playheadOffsets;
+  private AudioTrack audioTrack;
+  private int outputSampleRate;
+  private int bufferSize;
+  private long bufferSizeUs;
+
+  private long smoothedPlayheadOffsetUs;
+  private long lastPlayheadSampleTimeUs;
+  private boolean audioTimestampSet;
+  private long lastTimestampSampleTimeUs;
+
+  private Method getLatencyMethod;
+  private int outputPcmFrameSize;
+  private long resumeSystemTimeUs;
+  private long latencyUs;
+  private boolean hasData;
+
+  private boolean needsPassthroughWorkarounds;
+  private @Nullable AudioTimestampV19 audioTimestamp;
+  private boolean shouldSampleLatency;
+  private long lastLatencySampleTimeUs;
+  private long lastRawPlaybackHeadPosition;
+  private long rawPlaybackHeadWrapCount;
+  private long passthroughWorkaroundPauseOffset;
+  private int nextPlayheadOffsetIndex;
+  private int playheadOffsetCount;
+  private long stopTimestampUs;
+  private long forceResetWorkaroundTimeMs;
+  private long stopPlaybackHeadPosition;
+  private long endPlaybackHeadPosition;
+
+  /**
+   * Creates a new audio track position tracker.
+   *
+   * @param listener A listener for position tracking events.
+   */
+  public AudioTrackPositionTracker(Listener listener) {
+    this.listener = Assertions.checkNotNull(listener);
+    if (Util.SDK_INT >= 18) {
+      try {
+        getLatencyMethod = AudioTrack.class.getMethod("getLatency", (Class<?>[]) null);
+      } catch (NoSuchMethodException e) {
+        // There's no guarantee this method exists. Do nothing.
+      }
+    }
+    playheadOffsets = new long[MAX_PLAYHEAD_OFFSET_COUNT];
+  }
+
+  /**
+   * Sets the {@link AudioTrack} to wrap. Subsequent method calls on this instance relate to this
+   * track's position, until the next call to {@link #reset()}.
+   *
+   * @param audioTrack The audio track to wrap.
+   * @param outputEncoding The encoding of the audio track.
+   * @param outputPcmFrameSize For PCM output encodings, the frame size. The value is ignored
+   *     otherwise.
+   * @param bufferSize The audio track buffer size in bytes.
+   */
+  public void setAudioTrack(
+      AudioTrack audioTrack,
+      @C.Encoding int outputEncoding,
+      int outputPcmFrameSize,
+      int bufferSize) {
+    this.audioTrack = audioTrack;
+    this.bufferSize = bufferSize;
+    this.outputPcmFrameSize = outputPcmFrameSize;
+    outputSampleRate = audioTrack.getSampleRate();
+    needsPassthroughWorkarounds = needsPassthroughWorkarounds(outputEncoding);
+    boolean isOutputPcm = Util.isEncodingPcm(outputEncoding);
+    bufferSizeUs = isOutputPcm ? framesToDurationUs(bufferSize / outputPcmFrameSize) : C.TIME_UNSET;
+    if (Util.SDK_INT >= 19) {
+      audioTimestamp = new AudioTimestampV19(audioTrack);
+    }
+    shouldSampleLatency = isOutputPcm && getLatencyMethod != null;
+    lastRawPlaybackHeadPosition = 0;
+    rawPlaybackHeadWrapCount = 0;
+    passthroughWorkaroundPauseOffset = 0;
+    hasData = false;
+    stopTimestampUs = C.TIME_UNSET;
+    forceResetWorkaroundTimeMs = C.TIME_UNSET;
+    latencyUs = 0;
+  }
+
+  public long getCurrentPositionUs(boolean sourceEnded) {
+    if (audioTrack.getPlayState() == PLAYSTATE_PLAYING) {
+      maybeSampleSyncParams();
+    }
+
+    // If the device supports it, use the playback timestamp from AudioTrack.getTimestamp.
+    // Otherwise, derive a smoothed position by sampling the track's frame position.
+    long systemTimeUs = System.nanoTime() / 1000;
+    long positionUs;
+    if (audioTimestamp != null && audioTimestampSet) {
+      // Calculate the speed-adjusted position using the timestamp (which may be in the future).
+      long elapsedSinceTimestampUs = systemTimeUs - audioTimestamp.getTimestampSystemTimeUs();
+      long elapsedSinceTimestampFrames = durationUsToFrames(elapsedSinceTimestampUs);
+      long elapsedFrames =
+          audioTimestamp.getTimestampPositionFrames() + elapsedSinceTimestampFrames;
+      positionUs = framesToDurationUs(elapsedFrames);
+    } else {
+      if (playheadOffsetCount == 0) {
+        // The AudioTrack has started, but we don't have any samples to compute a smoothed position.
+        positionUs = getPlaybackHeadPositionUs();
+      } else {
+        // getPlaybackHeadPositionUs() only has a granularity of ~20 ms, so we base the position off
+        // the system clock (and a smoothed offset between it and the playhead position) so as to
+        // prevent jitter in the reported positions.
+        positionUs = systemTimeUs + smoothedPlayheadOffsetUs;
+      }
+      if (!sourceEnded) {
+        positionUs -= latencyUs;
+      }
+    }
+    return positionUs;
+  }
+
+  /** Starts position tracking. Must be called immediately before {@link AudioTrack#play()}. */
+  public void start() {
+    resumeSystemTimeUs = System.nanoTime() / 1000;
+  }
+
+  /** Returns whether the audio track is in the playing state. */
+  public boolean isPlaying() {
+    return audioTrack.getPlayState() == PLAYSTATE_PLAYING;
+  }
+
+  /**
+   * Checks the state of the audio track and returns whether the caller can write data to the track.
+   * Notifies {@link Listener#onUnderrun(int, long)} if the track has underrun.
+   *
+   * @param writtenFrames The number of frames that have been written.
+   * @return Whether the caller can write data to the track.
+   */
+  public boolean mayHandleBuffer(long writtenFrames) {
+    @PlayState int playState = audioTrack.getPlayState();
+    if (needsPassthroughWorkarounds) {
+      // An AC-3 audio track continues to play data written while it is paused. Stop writing so its
+      // buffer empties. See [Internal: b/18899620].
+      if (playState == PLAYSTATE_PAUSED) {
+        // We force an underrun to pause the track, so don't notify the listener in this case.
+        hasData = false;
+        return false;
+      }
+
+      // A new AC-3 audio track's playback position continues to increase from the old track's
+      // position for a short time after is has been released. Avoid writing data until the playback
+      // head position actually returns to zero.
+      if (playState == PLAYSTATE_STOPPED && getPlaybackHeadPosition() == 0) {
+        return false;
+      }
+    }
+
+    boolean hadData = hasData;
+    hasData = hasPendingData(writtenFrames);
+    if (hadData && !hasData && playState != PLAYSTATE_STOPPED && listener != null) {
+      listener.onUnderrun(bufferSize, C.usToMs(bufferSizeUs));
+    }
+
+    return true;
+  }
+
+  /**
+   * Returns an estimate of the number of additional bytes that can be written to the audio track's
+   * buffer without running out of space.
+   *
+   * <p>May only be called if the output encoding is one of the PCM encodings.
+   *
+   * @param writtenBytes The number of bytes written to the audio track so far.
+   * @return An estimate of the number of bytes that can be written.
+   */
+  public int getAvailableBufferSize(long writtenBytes) {
+    int bytesPending = (int) (writtenBytes - (getPlaybackHeadPosition() * outputPcmFrameSize));
+    return bufferSize - bytesPending;
+  }
+
+  /** Returns whether the track is in an invalid state and must be recreated. */
+  public boolean isStalled(long writtenFrames) {
+    return forceResetWorkaroundTimeMs != C.TIME_UNSET
+        && writtenFrames > 0
+        && SystemClock.elapsedRealtime() - forceResetWorkaroundTimeMs
+            >= FORCE_RESET_WORKAROUND_TIMEOUT_MS;
+  }
+
+  /**
+   * Records the writing position at which the stream ended, so that the reported position can
+   * continue to increment while remaining data is played out.
+   *
+   * @param writtenFrames The number of frames that have been written.
+   */
+  public void handleEndOfStream(long writtenFrames) {
+    stopPlaybackHeadPosition = getPlaybackHeadPosition();
+    stopTimestampUs = SystemClock.elapsedRealtime() * 1000;
+    endPlaybackHeadPosition = writtenFrames;
+  }
+
+  /**
+   * Returns whether the audio track has any pending data to play out at its current position.
+   *
+   * @param writtenFrames The number of frames written to the audio track.
+   * @return Whether the audio track has any pending data to play out.
+   */
+  public boolean hasPendingData(long writtenFrames) {
+    return writtenFrames > getPlaybackHeadPosition()
+        || forceHasPendingData();
+  }
+
+  /**
+   * Pauses the audio track position tracker, returning whether the audio track needs to be paused
+   * to cause playback to pause. If {@code false} is returned the audio track will pause without
+   * further interaction, as the end of stream has been handled.
+   */
+  public boolean pause() {
+    resetSyncParams();
+    return stopTimestampUs == C.TIME_UNSET;
+  }
+
+  /**
+   * Resets the position tracker. Should be called when the audio track previous passed to {@link
+   * #setAudioTrack(AudioTrack, int, int, int)} is no longer in use.
+   */
+  public void reset() {
+    resetSyncParams();
+    audioTrack = null;
+    audioTimestamp = null;
+  }
+
+  private void maybeSampleSyncParams() {
+    long playbackPositionUs = getPlaybackHeadPositionUs();
+    if (playbackPositionUs == 0) {
+      // The AudioTrack hasn't output anything yet.
+      return;
+    }
+    long systemTimeUs = System.nanoTime() / 1000;
+    if (systemTimeUs - lastPlayheadSampleTimeUs >= MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US) {
+      // Take a new sample and update the smoothed offset between the system clock and the playhead.
+      playheadOffsets[nextPlayheadOffsetIndex] = playbackPositionUs - systemTimeUs;
+      nextPlayheadOffsetIndex = (nextPlayheadOffsetIndex + 1) % MAX_PLAYHEAD_OFFSET_COUNT;
+      if (playheadOffsetCount < MAX_PLAYHEAD_OFFSET_COUNT) {
+        playheadOffsetCount++;
+      }
+      lastPlayheadSampleTimeUs = systemTimeUs;
+      smoothedPlayheadOffsetUs = 0;
+      for (int i = 0; i < playheadOffsetCount; i++) {
+        smoothedPlayheadOffsetUs += playheadOffsets[i] / playheadOffsetCount;
+      }
+    }
+
+    if (needsPassthroughWorkarounds) {
+      // Don't sample the timestamp and latency if this is an AC-3 passthrough AudioTrack on
+      // platform API versions 21/22, as incorrect values are returned. See [Internal: b/21145353].
+      return;
+    }
+    maybeUpdateAudioTimestamp(systemTimeUs, playbackPositionUs);
+    maybeUpdateLatency(systemTimeUs);
+  }
+
+  private void maybeUpdateAudioTimestamp(long systemTimeUs, long playbackPositionUs) {
+    if (audioTimestamp != null
+        && systemTimeUs - lastTimestampSampleTimeUs >= MIN_TIMESTAMP_SAMPLE_INTERVAL_US) {
+      audioTimestampSet = audioTimestamp.maybeUpdateTimestamp();
+      if (audioTimestampSet) {
+        // Perform sanity checks on the timestamp.
+        long audioTimestampSystemTimeUs = audioTimestamp.getTimestampSystemTimeUs();
+        long audioTimestampPositionFrames = audioTimestamp.getTimestampPositionFrames();
+        if (audioTimestampSystemTimeUs < resumeSystemTimeUs) {
+          // The timestamp corresponds to a time before the track was most recently resumed.
+          audioTimestampSet = false;
+        } else if (Math.abs(audioTimestampSystemTimeUs - systemTimeUs)
+            > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
+          listener.onSystemTimeUsMismatch(
+              audioTimestampPositionFrames,
+              audioTimestampSystemTimeUs,
+              systemTimeUs,
+              playbackPositionUs);
+          audioTimestampSet = false;
+        } else if (Math.abs(framesToDurationUs(audioTimestampPositionFrames) - playbackPositionUs)
+            > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
+          listener.onPositionFramesMismatch(
+              audioTimestampPositionFrames,
+              audioTimestampSystemTimeUs,
+              systemTimeUs,
+              playbackPositionUs);
+          audioTimestampSet = false;
+        }
+      }
+      lastTimestampSampleTimeUs = systemTimeUs;
+    }
+  }
+
+  private void maybeUpdateLatency(long systemTimeUs) {
+    if (shouldSampleLatency
+        && systemTimeUs - lastLatencySampleTimeUs >= MIN_LATENCY_SAMPLE_INTERVAL_US) {
+      try {
+        // Compute the audio track latency, excluding the latency due to the buffer (leaving
+        // latency due to the mixer and audio hardware driver).
+        latencyUs =
+            (Integer) getLatencyMethod.invoke(audioTrack, (Object[]) null) * 1000L - bufferSizeUs;
+        // Sanity check that the latency is non-negative.
+        latencyUs = Math.max(latencyUs, 0);
+        // Sanity check that the latency isn't too large.
+        if (latencyUs > MAX_LATENCY_US) {
+          listener.onInvalidLatency(latencyUs);
+          latencyUs = 0;
+        }
+      } catch (Exception e) {
+        // The method existed, but doesn't work. Don't try again.
+        getLatencyMethod = null;
+      }
+      lastLatencySampleTimeUs = systemTimeUs;
+    }
+  }
+
+  private long framesToDurationUs(long frameCount) {
+    return (frameCount * C.MICROS_PER_SECOND) / outputSampleRate;
+  }
+
+  private long durationUsToFrames(long durationUs) {
+    return (durationUs * outputSampleRate) / C.MICROS_PER_SECOND;
+  }
+
+  private void resetSyncParams() {
+    smoothedPlayheadOffsetUs = 0;
+    playheadOffsetCount = 0;
+    nextPlayheadOffsetIndex = 0;
+    lastPlayheadSampleTimeUs = 0;
+    audioTimestampSet = false;
+    lastTimestampSampleTimeUs = 0;
+  }
+
+  /**
+   * If passthrough workarounds are enabled, pausing is implemented by forcing the AudioTrack to
+   * underrun. In this case, still behave as if we have pending data, otherwise writing won't
+   * resume.
+   */
+  private boolean forceHasPendingData() {
+    return needsPassthroughWorkarounds
+        && audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PAUSED
+        && getPlaybackHeadPosition() == 0;
+  }
+
+  /**
+   * Returns whether to work around problems with passthrough audio tracks. See [Internal:
+   * b/18899620, b/19187573, b/21145353].
+   */
+  private static boolean needsPassthroughWorkarounds(@C.Encoding int outputEncoding) {
+    return Util.SDK_INT < 23
+        && (outputEncoding == C.ENCODING_AC3 || outputEncoding == C.ENCODING_E_AC3);
+  }
+
+  private long getPlaybackHeadPositionUs() {
+    return framesToDurationUs(getPlaybackHeadPosition());
+  }
+
+  /**
+   * {@link AudioTrack#getPlaybackHeadPosition()} returns a value intended to be interpreted as an
+   * unsigned 32 bit integer, which also wraps around periodically. This method returns the playback
+   * head position as a long that will only wrap around if the value exceeds {@link Long#MAX_VALUE}
+   * (which in practice will never happen).
+   *
+   * @return The playback head position, in frames.
+   */
+  private long getPlaybackHeadPosition() {
+    if (stopTimestampUs != C.TIME_UNSET) {
+      // Simulate the playback head position up to the total number of frames submitted.
+      long elapsedTimeSinceStopUs = (SystemClock.elapsedRealtime() * 1000) - stopTimestampUs;
+      long framesSinceStop = (elapsedTimeSinceStopUs * outputSampleRate) / C.MICROS_PER_SECOND;
+      return Math.min(endPlaybackHeadPosition, stopPlaybackHeadPosition + framesSinceStop);
+    }
+
+    int state = audioTrack.getPlayState();
+    if (state == PLAYSTATE_STOPPED) {
+      // The audio track hasn't been started.
+      return 0;
+    }
+
+    long rawPlaybackHeadPosition = 0xFFFFFFFFL & audioTrack.getPlaybackHeadPosition();
+    if (needsPassthroughWorkarounds) {
+      // Work around an issue with passthrough/direct AudioTracks on platform API versions 21/22
+      // where the playback head position jumps back to zero on paused passthrough/direct audio
+      // tracks. See [Internal: b/19187573].
+      if (state == PLAYSTATE_PAUSED && rawPlaybackHeadPosition == 0) {
+        passthroughWorkaroundPauseOffset = lastRawPlaybackHeadPosition;
+      }
+      rawPlaybackHeadPosition += passthroughWorkaroundPauseOffset;
+    }
+
+    if (Util.SDK_INT <= 28) {
+      if (rawPlaybackHeadPosition == 0
+          && lastRawPlaybackHeadPosition > 0
+          && state == PLAYSTATE_PLAYING) {
+        // If connecting a Bluetooth audio device fails, the AudioTrack may be left in a state
+        // where its Java API is in the playing state, but the native track is stopped. When this
+        // happens the playback head position gets stuck at zero. In this case, return the old
+        // playback head position and force the track to be reset after
+        // {@link #FORCE_RESET_WORKAROUND_TIMEOUT_MS} has elapsed.
+        if (forceResetWorkaroundTimeMs == C.TIME_UNSET) {
+          forceResetWorkaroundTimeMs = SystemClock.elapsedRealtime();
+        }
+        return lastRawPlaybackHeadPosition;
+      } else {
+        forceResetWorkaroundTimeMs = C.TIME_UNSET;
+      }
+    }
+
+    if (lastRawPlaybackHeadPosition > rawPlaybackHeadPosition) {
+      // The value must have wrapped around.
+      rawPlaybackHeadWrapCount++;
+    }
+    lastRawPlaybackHeadPosition = rawPlaybackHeadPosition;
+    return rawPlaybackHeadPosition + (rawPlaybackHeadWrapCount << 32);
+  }
+
+  @TargetApi(19)
+  private static final class AudioTimestampV19 {
+
+    private final AudioTrack audioTrack;
+    private final AudioTimestamp audioTimestamp;
+
+    private long rawTimestampFramePositionWrapCount;
+    private long lastTimestampRawPositionFrames;
+    private long lastTimestampPositionFrames;
+
+    /**
+     * Creates a new {@link AudioTimestamp} wrapper.
+     *
+     * @param audioTrack The audio track that will provide timestamps.
+     */
+    public AudioTimestampV19(AudioTrack audioTrack) {
+      this.audioTrack = audioTrack;
+      audioTimestamp = new AudioTimestamp();
+    }
+
+    /**
+     * Attempts to update the audio track timestamp. Returns {@code true} if the timestamp was
+     * updated, in which case the updated timestamp system time and position can be accessed with
+     * {@link #getTimestampSystemTimeUs()} and {@link #getTimestampPositionFrames()}. Returns {@code
+     * false} if no timestamp is available, in which case those methods should not be called.
+     */
+    public boolean maybeUpdateTimestamp() {
+      boolean updated = audioTrack.getTimestamp(audioTimestamp);
+      if (updated) {
+        long rawPositionFrames = audioTimestamp.framePosition;
+        if (lastTimestampRawPositionFrames > rawPositionFrames) {
+          // The value must have wrapped around.
+          rawTimestampFramePositionWrapCount++;
+        }
+        lastTimestampRawPositionFrames = rawPositionFrames;
+        lastTimestampPositionFrames =
+            rawPositionFrames + (rawTimestampFramePositionWrapCount << 32);
+      }
+      return updated;
+    }
+
+    /**
+     * Returns the {@link android.media.AudioTimestamp#nanoTime} obtained during the most recent
+     * call to {@link #maybeUpdateTimestamp()} that returned true.
+     *
+     * @return The nanoTime obtained during the most recent call to {@link #maybeUpdateTimestamp()}
+     *     that returned true.
+     */
+    public long getTimestampSystemTimeUs() {
+      return audioTimestamp.nanoTime / 1000;
+    }
+
+    /**
+     * Returns the {@link android.media.AudioTimestamp#framePosition} obtained during the most
+     * recent call to {@link #maybeUpdateTimestamp()} that returned true. The value is adjusted so
+     * that wrap around only occurs if the value exceeds {@link Long#MAX_VALUE} (which in practice
+     * will never happen).
+     *
+     * @return The framePosition obtained during the most recent call to {@link
+     *     #maybeUpdateTimestamp()} that returned true.
+     */
+    public long getTimestampPositionFrames() {
+      return lastTimestampPositionFrames;
+    }
+  }
+}

library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java

@@ -19,7 +19,6 @@ import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.media.AudioFormat;
 import android.media.AudioManager;
-import android.media.AudioTimestamp;
 import android.media.AudioTrack;
 import android.os.ConditionVariable;
 import android.os.SystemClock;
@@ -32,7 +31,6 @@ import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
-import java.lang.reflect.Method;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.ArrayDeque;
@@ -50,8 +48,8 @@ import java.util.ArrayList;
 public final class DefaultAudioSink implements AudioSink {
 
   /**
-   * Thrown when {@link AudioTrack#getTimestamp} returns a spurious timestamp, if
+   * Thrown when the audio track has provided a spurious timestamp, if {@link
-   * {@link #failOnSpuriousAudioTimestamp} is set.
+   * #failOnSpuriousAudioTimestamp} is set.
    */
   public static final class InvalidAudioTrackTimestampException extends RuntimeException {
 
@@ -84,22 +82,6 @@ public final class DefaultAudioSink implements AudioSink {
    */
   private static final int BUFFER_MULTIPLICATION_FACTOR = 4;
 
-  /** {@link AudioTrack} playback states. */
-  @Retention(RetentionPolicy.SOURCE)
-  @IntDef({PLAYSTATE_STOPPED, PLAYSTATE_PAUSED, PLAYSTATE_PLAYING})
-  private @interface PlayState {}
-  /**
-   * @see AudioTrack#PLAYSTATE_STOPPED
-   */
-  private static final int PLAYSTATE_STOPPED = AudioTrack.PLAYSTATE_STOPPED;
-  /**
-   * @see AudioTrack#PLAYSTATE_PAUSED
-   */
-  private static final int PLAYSTATE_PAUSED = AudioTrack.PLAYSTATE_PAUSED;
-  /**
-   * @see AudioTrack#PLAYSTATE_PLAYING
-   */
-  private static final int PLAYSTATE_PLAYING = AudioTrack.PLAYSTATE_PLAYING;
   /**
    * @see AudioTrack#ERROR_BAD_VALUE
    */
@@ -124,21 +106,6 @@ public final class DefaultAudioSink implements AudioSink {
 
   private static final String TAG = "AudioTrack";
 
-  /**
-   * AudioTrack timestamps are deemed spurious if they are offset from the system clock by more
-   * than this amount.
-   * <p>
-   * This is a fail safe that should not be required on correctly functioning devices.
-   */
-  private static final long MAX_AUDIO_TIMESTAMP_OFFSET_US = 5 * C.MICROS_PER_SECOND;
-
-  /**
-   * AudioTrack latencies are deemed impossibly large if they are greater than this amount.
-   * <p>
-   * This is a fail safe that should not be required on correctly functioning devices.
-   */
-  private static final long MAX_LATENCY_US = 5 * C.MICROS_PER_SECOND;
-
   /**
    * Represents states of the {@link #startMediaTimeUs} value.
    */
@@ -149,10 +116,6 @@ public final class DefaultAudioSink implements AudioSink {
   private static final int START_IN_SYNC = 1;
   private static final int START_NEED_SYNC = 2;
 
-  private static final int MAX_PLAYHEAD_OFFSET_COUNT = 10;
-  private static final int MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US = 30000;
-  private static final int MIN_TIMESTAMP_SAMPLE_INTERVAL_US = 500000;
-
   /**
    * Whether to enable a workaround for an issue where an audio effect does not keep its session
    * active across releasing/initializing a new audio track, on platform builds where
@@ -179,9 +142,7 @@ public final class DefaultAudioSink implements AudioSink {
   private final AudioProcessor[] toIntPcmAvailableAudioProcessors;
   private final AudioProcessor[] toFloatPcmAvailableAudioProcessors;
   private final ConditionVariable releasingConditionVariable;
-  private final long[] playheadOffsets;
+  private final AudioTrackPositionTracker audioTrackPositionTracker;
-  private final AudioTrackUtil audioTrackUtil;
-  private final AudioTrackPositionErrorListener audioTrackPositionErrorListener;
   private final ArrayDeque<PlaybackParametersCheckpoint> playbackParametersCheckpoints;
 
   @Nullable private Listener listener;
@@ -200,7 +161,6 @@ public final class DefaultAudioSink implements AudioSink {
   private boolean processingEnabled;
   private boolean canApplyPlaybackParameters;
   private int bufferSize;
-  private long bufferSizeUs;
 
   private PlaybackParameters drainingPlaybackParameters;
   private PlaybackParameters playbackParameters;
@@ -210,14 +170,6 @@ public final class DefaultAudioSink implements AudioSink {
   private ByteBuffer avSyncHeader;
   private int bytesUntilNextAvSync;
 
-  private int nextPlayheadOffsetIndex;
-  private int playheadOffsetCount;
-  private long smoothedPlayheadOffsetUs;
-  private long lastPlayheadSampleTimeUs;
-  private boolean audioTimestampSet;
-  private long lastTimestampSampleTimeUs;
-
-  private Method getLatencyMethod;
   private int pcmFrameSize;
   private long submittedPcmBytes;
   private long submittedEncodedFrames;
@@ -227,8 +179,6 @@ public final class DefaultAudioSink implements AudioSink {
   private int framesPerEncodedSample;
   private @StartMediaTimeState int startMediaTimeState;
   private long startMediaTimeUs;
-  private long resumeSystemTimeUs;
-  private long latencyUs;
   private float volume;
 
   private AudioProcessor[] audioProcessors;
@@ -243,7 +193,6 @@ public final class DefaultAudioSink implements AudioSink {
   private boolean playing;
   private int audioSessionId;
   private boolean tunneling;
-  private boolean hasData;
   private long lastFeedElapsedRealtimeMs;
 
   /**
@@ -274,19 +223,7 @@ public final class DefaultAudioSink implements AudioSink {
     this.audioCapabilities = audioCapabilities;
     this.enableConvertHighResIntPcmToFloat = enableConvertHighResIntPcmToFloat;
     releasingConditionVariable = new ConditionVariable(true);
-    if (Util.SDK_INT >= 18) {
+    audioTrackPositionTracker = new AudioTrackPositionTracker(new PositionTrackerListener());
-      try {
-        getLatencyMethod = AudioTrack.class.getMethod("getLatency", (Class<?>[]) null);
-      } catch (NoSuchMethodException e) {
-        // There's no guarantee this method exists. Do nothing.
-      }
-    }
-    if (Util.SDK_INT >= 19) {
-      audioTrackUtil = new AudioTrackUtilV19();
-    } else {
-      audioTrackUtil = new AudioTrackUtil();
-    }
-    audioTrackPositionErrorListener = new DefaultAudioTrackPositionErrorListener();
     channelMappingAudioProcessor = new ChannelMappingAudioProcessor();
     trimmingAudioProcessor = new TrimmingAudioProcessor();
     sonicAudioProcessor = new SonicAudioProcessor();
@@ -298,7 +235,6 @@ public final class DefaultAudioSink implements AudioSink {
         audioProcessors, 0, toIntPcmAvailableAudioProcessors, 3, audioProcessors.length);
     toIntPcmAvailableAudioProcessors[3 + audioProcessors.length] = sonicAudioProcessor;
     toFloatPcmAvailableAudioProcessors = new AudioProcessor[] {new FloatResamplingAudioProcessor()};
-    playheadOffsets = new long[MAX_PLAYHEAD_OFFSET_COUNT];
     volume = 1.0f;
     startMediaTimeState = START_NOT_SET;
     audioAttributes = AudioAttributes.DEFAULT;
@@ -331,40 +267,10 @@ public final class DefaultAudioSink implements AudioSink {
 
   @Override
   public long getCurrentPositionUs(boolean sourceEnded) {
-    if (!hasCurrentPositionUs()) {
+    if (!isInitialized() || startMediaTimeState == START_NOT_SET) {
       return CURRENT_POSITION_NOT_SET;
     }
-
+    long positionUs = audioTrackPositionTracker.getCurrentPositionUs(sourceEnded);
-    if (audioTrack.getPlayState() == PLAYSTATE_PLAYING) {
-      maybeSampleSyncParams();
-    }
-
-    // If the device supports it, use the playback timestamp from AudioTrack.getTimestamp.
-    // Otherwise, derive a smoothed position by sampling the track's frame position.
-    long systemClockUs = System.nanoTime() / 1000;
-    long positionUs;
-    if (audioTimestampSet) {
-      // Calculate the speed-adjusted position using the timestamp (which may be in the future).
-      long elapsedSinceTimestampUs = systemClockUs - audioTrackUtil.getTimestampSystemTimeUs();
-      long elapsedSinceTimestampFrames = durationUsToFrames(elapsedSinceTimestampUs);
-      long elapsedFrames =
-          audioTrackUtil.getTimestampPositionFrames() + elapsedSinceTimestampFrames;
-      positionUs = framesToDurationUs(elapsedFrames);
-    } else {
-      if (playheadOffsetCount == 0) {
-        // The AudioTrack has started, but we don't have any samples to compute a smoothed position.
-        positionUs = audioTrackUtil.getPositionUs();
-      } else {
-        // getPlayheadPositionUs() only has a granularity of ~20 ms, so we base the position off the
-        // system clock (and a smoothed offset between it and the playhead position) so as to
-        // prevent jitter in the reported positions.
-        positionUs = systemClockUs + smoothedPlayheadOffsetUs;
-      }
-      if (!sourceEnded) {
-        positionUs -= latencyUs;
-      }
-    }
-
     positionUs = Math.min(positionUs, framesToDurationUs(getWrittenFrames()));
     return startMediaTimeUs + applySpeedup(positionUs);
   }
@@ -497,8 +403,6 @@ public final class DefaultAudioSink implements AudioSink {
         bufferSize = (int) (PASSTHROUGH_BUFFER_DURATION_US * 192 * 6 * 1024 / C.MICROS_PER_SECOND);
       }
     }
-    bufferSizeUs =
-        isInputPcm ? framesToDurationUs(bufferSize / outputPcmFrameSize) : C.TIME_UNSET;
   }
 
   private void resetAudioProcessors() {
@@ -557,17 +461,16 @@ public final class DefaultAudioSink implements AudioSink {
       }
     }
 
-    audioTrackUtil.reconfigure(audioTrack, needsPassthroughWorkarounds());
+    audioTrackPositionTracker.setAudioTrack(
+        audioTrack, outputEncoding, outputPcmFrameSize, bufferSize);
     setVolumeInternal();
-    hasData = false;
-    latencyUs = 0;
   }
 
   @Override
   public void play() {
     playing = true;
     if (isInitialized()) {
-      resumeSystemTimeUs = System.nanoTime() / 1000;
+      audioTrackPositionTracker.start();
       audioTrack.play();
     }
   }
@@ -592,30 +495,10 @@ public final class DefaultAudioSink implements AudioSink {
       }
     }
 
-    if (needsPassthroughWorkarounds()) {
+    if (!audioTrackPositionTracker.mayHandleBuffer(getWrittenFrames())) {
-      // An AC-3 audio track continues to play data written while it is paused. Stop writing so its
-      // buffer empties. See [Internal: b/18899620].
-      if (audioTrack.getPlayState() == PLAYSTATE_PAUSED) {
-        // We force an underrun to pause the track, so don't notify the listener in this case.
-        hasData = false;
       return false;
     }
 
-      // A new AC-3 audio track's playback position continues to increase from the old track's
-      // position for a short time after is has been released. Avoid writing data until the playback
-      // head position actually returns to zero.
-      if (audioTrack.getPlayState() == PLAYSTATE_STOPPED
-          && audioTrack.getPlaybackHeadPosition() != 0) {
-        return false;
-      }
-    }
-
-    boolean hadData = hasData;
-    hasData = hasPendingData();
-    if (hadData && !hasData && audioTrack.getPlayState() != PLAYSTATE_STOPPED && listener != null) {
-      audioTrackPositionErrorListener.onUnderrun(bufferSize, C.usToMs(bufferSizeUs));
-    }
-
     if (inputBuffer == null) {
       // We are seeing this buffer for the first time.
       if (!buffer.hasRemaining()) {
@@ -694,7 +577,7 @@ public final class DefaultAudioSink implements AudioSink {
       return true;
     }
 
-    if (audioTrackUtil.needsReset(getWrittenFrames())) {
+    if (audioTrackPositionTracker.isStalled(getWrittenFrames())) {
       Log.w(TAG, "Resetting stalled audio track");
       reset();
       return true;
@@ -757,9 +640,7 @@ public final class DefaultAudioSink implements AudioSink {
     int bytesWritten = 0;
     if (Util.SDK_INT < 21) { // isInputPcm == true
       // Work out how many bytes we can write without the risk of blocking.
-      int bytesPending =
+      int bytesToWrite = audioTrackPositionTracker.getAvailableBufferSize(writtenPcmBytes);
-          (int) (writtenPcmBytes - (audioTrackUtil.getPlaybackHeadPosition() * outputPcmFrameSize));
-      int bytesToWrite = bufferSize - bytesPending;
       if (bytesToWrite > 0) {
         bytesToWrite = Math.min(bytesRemaining, bytesToWrite);
         bytesWritten = audioTrack.write(preV21OutputBuffer, preV21OutputBufferOffset, bytesToWrite);
@@ -801,7 +682,8 @@ public final class DefaultAudioSink implements AudioSink {
 
     if (drainAudioProcessorsToEndOfStream()) {
       // The audio processors have drained, so drain the underlying audio track.
-      audioTrackUtil.handleEndOfStream(getWrittenFrames());
+      audioTrackPositionTracker.handleEndOfStream(getWrittenFrames());
+      audioTrack.stop();
       bytesUntilNextAvSync = 0;
       handledEndOfStream = true;
     }
@@ -844,9 +726,7 @@ public final class DefaultAudioSink implements AudioSink {
 
   @Override
   public boolean hasPendingData() {
-    return isInitialized()
+    return isInitialized() && audioTrackPositionTracker.hasPendingData(getWrittenFrames());
-        && (getWrittenFrames() > audioTrackUtil.getPlaybackHeadPosition()
-        || overrideHasPendingData());
   }
 
   @Override
@@ -942,9 +822,8 @@ public final class DefaultAudioSink implements AudioSink {
   @Override
   public void pause() {
     playing = false;
-    if (isInitialized()) {
+    if (isInitialized() && audioTrackPositionTracker.pause()) {
-      resetSyncParams();
+      audioTrack.pause();
-      audioTrackUtil.pause();
     }
   }
 
@@ -977,14 +856,13 @@ public final class DefaultAudioSink implements AudioSink {
       avSyncHeader = null;
       bytesUntilNextAvSync = 0;
       startMediaTimeState = START_NOT_SET;
-      resetSyncParams();
+      if (audioTrackPositionTracker.isPlaying()) {
-      if (audioTrack.getPlayState() == PLAYSTATE_PLAYING) {
         audioTrack.pause();
       }
       // AudioTrack.release can take some time, so we call it on a background thread.
       final AudioTrack toRelease = audioTrack;
       audioTrack = null;
-      audioTrackUtil.reconfigure(null, false);
+      audioTrackPositionTracker.reset();
       releasingConditionVariable.close();
       new Thread() {
         @Override
@@ -1033,13 +911,6 @@ public final class DefaultAudioSink implements AudioSink {
     }.start();
   }
 
-  /**
-   * Returns whether {@link #getCurrentPositionUs} can return the current playback position.
-   */
-  private boolean hasCurrentPositionUs() {
-    return isInitialized() && startMediaTimeState != START_NOT_SET;
-  }
-
   /**
    * Returns the underlying audio track {@code positionUs} with any applicable speedup applied.
    */
@@ -1067,85 +938,6 @@ public final class DefaultAudioSink implements AudioSink {
             positionUs - playbackParametersPositionUs, playbackParameters.speed);
   }
 
-  /**
-   * Updates the audio track latency and playback position parameters.
-   */
-  private void maybeSampleSyncParams() {
-    long playbackPositionUs = audioTrackUtil.getPositionUs();
-    if (playbackPositionUs == 0) {
-      // The AudioTrack hasn't output anything yet.
-      return;
-    }
-    long systemTimeUs = System.nanoTime() / 1000;
-    if (systemTimeUs - lastPlayheadSampleTimeUs >= MIN_PLAYHEAD_OFFSET_SAMPLE_INTERVAL_US) {
-      // Take a new sample and update the smoothed offset between the system clock and the playhead.
-      playheadOffsets[nextPlayheadOffsetIndex] = playbackPositionUs - systemTimeUs;
-      nextPlayheadOffsetIndex = (nextPlayheadOffsetIndex + 1) % MAX_PLAYHEAD_OFFSET_COUNT;
-      if (playheadOffsetCount < MAX_PLAYHEAD_OFFSET_COUNT) {
-        playheadOffsetCount++;
-      }
-      lastPlayheadSampleTimeUs = systemTimeUs;
-      smoothedPlayheadOffsetUs = 0;
-      for (int i = 0; i < playheadOffsetCount; i++) {
-        smoothedPlayheadOffsetUs += playheadOffsets[i] / playheadOffsetCount;
-      }
-    }
-
-    if (needsPassthroughWorkarounds()) {
-      // Don't sample the timestamp and latency if this is an AC-3 passthrough AudioTrack on
-      // platform API versions 21/22, as incorrect values are returned. See [Internal: b/21145353].
-      return;
-    }
-
-    if (systemTimeUs - lastTimestampSampleTimeUs >= MIN_TIMESTAMP_SAMPLE_INTERVAL_US) {
-      audioTimestampSet = audioTrackUtil.updateTimestamp();
-      if (audioTimestampSet) {
-        // Perform sanity checks on the timestamp.
-        long audioTimestampSystemTimeUs = audioTrackUtil.getTimestampSystemTimeUs();
-        long audioTimestampPositionFrames = audioTrackUtil.getTimestampPositionFrames();
-        if (audioTimestampSystemTimeUs < resumeSystemTimeUs) {
-          // The timestamp corresponds to a time before the track was most recently resumed.
-          audioTimestampSet = false;
-        } else if (Math.abs(audioTimestampSystemTimeUs - systemTimeUs)
-            > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
-          audioTrackPositionErrorListener.onSystemTimeUsMismatch(
-              audioTimestampPositionFrames,
-              audioTimestampSystemTimeUs,
-              systemTimeUs,
-              playbackPositionUs);
-          audioTimestampSet = false;
-        } else if (Math.abs(framesToDurationUs(audioTimestampPositionFrames) - playbackPositionUs)
-            > MAX_AUDIO_TIMESTAMP_OFFSET_US) {
-          audioTrackPositionErrorListener.onPositionFramesMismatch(
-              audioTimestampPositionFrames,
-              audioTimestampSystemTimeUs,
-              systemTimeUs,
-              playbackPositionUs);
-          audioTimestampSet = false;
-        }
-      }
-      if (getLatencyMethod != null && isInputPcm) {
-        try {
-          // Compute the audio track latency, excluding the latency due to the buffer (leaving
-          // latency due to the mixer and audio hardware driver).
-          latencyUs = (Integer) getLatencyMethod.invoke(audioTrack, (Object[]) null) * 1000L
-              - bufferSizeUs;
-          // Sanity check that the latency is non-negative.
-          latencyUs = Math.max(latencyUs, 0);
-          // Sanity check that the latency isn't too large.
-          if (latencyUs > MAX_LATENCY_US) {
-            audioTrackPositionErrorListener.onInvalidLatency(latencyUs);
-            latencyUs = 0;
-          }
-        } catch (Exception e) {
-          // The method existed, but doesn't work. Don't try again.
-          getLatencyMethod = null;
-        }
-      }
-      lastTimestampSampleTimeUs = systemTimeUs;
-    }
-  }
-
   private boolean isInitialized() {
     return audioTrack != null;
   }
@@ -1170,36 +962,6 @@ public final class DefaultAudioSink implements AudioSink {
     return isInputPcm ? (writtenPcmBytes / outputPcmFrameSize) : writtenEncodedFrames;
   }
 
-  private void resetSyncParams() {
-    smoothedPlayheadOffsetUs = 0;
-    playheadOffsetCount = 0;
-    nextPlayheadOffsetIndex = 0;
-    lastPlayheadSampleTimeUs = 0;
-    audioTimestampSet = false;
-    lastTimestampSampleTimeUs = 0;
-  }
-
-  /**
-   * Returns whether to work around problems with passthrough audio tracks.
-   * See [Internal: b/18899620, b/19187573, b/21145353].
-   */
-  private boolean needsPassthroughWorkarounds() {
-    return Util.SDK_INT < 23
-        && (outputEncoding == C.ENCODING_AC3 || outputEncoding == C.ENCODING_E_AC3);
-  }
-
-  /**
-   * Returns whether the audio track should behave as though it has pending data. This is to work
-   * around an issue on platform API versions 21/22 where AC-3 audio tracks can't be paused, so we
-   * empty their buffers when paused. In this case, they should still behave as if they have
-   * pending data, otherwise writing will never resume.
-   */
-  private boolean overrideHasPendingData() {
-    return needsPassthroughWorkarounds()
-        && audioTrack.getPlayState() == PLAYSTATE_PAUSED
-        && audioTrack.getPlaybackHeadPosition() == 0;
-  }
-
   private AudioTrack initializeAudioTrack() throws InitializationException {
     AudioTrack audioTrack;
     if (Util.SDK_INT >= 21) {
@@ -1349,239 +1111,6 @@ public final class DefaultAudioSink implements AudioSink {
     audioTrack.setStereoVolume(volume, volume);
   }
 
-  /**
-   * Wraps an {@link AudioTrack} to expose useful utility methods.
-   */
-  private static class AudioTrackUtil {
-
-    private static final long FORCE_RESET_WORKAROUND_TIMEOUT_MS = 200;
-
-    protected AudioTrack audioTrack;
-    private boolean needsPassthroughWorkaround;
-    private int sampleRate;
-    private long lastRawPlaybackHeadPosition;
-    private long rawPlaybackHeadWrapCount;
-    private long passthroughWorkaroundPauseOffset;
-
-    private long stopTimestampUs;
-    private long forceResetWorkaroundTimeMs;
-    private long stopPlaybackHeadPosition;
-    private long endPlaybackHeadPosition;
-
-    /**
-     * Reconfigures the audio track utility helper to use the specified {@code audioTrack}.
-     *
-     * @param audioTrack The audio track to wrap.
-     * @param needsPassthroughWorkaround Whether to workaround issues with pausing AC-3 passthrough
-     *     audio tracks on platform API version 21/22.
-     */
-    public void reconfigure(AudioTrack audioTrack, boolean needsPassthroughWorkaround) {
-      this.audioTrack = audioTrack;
-      this.needsPassthroughWorkaround = needsPassthroughWorkaround;
-      stopTimestampUs = C.TIME_UNSET;
-      forceResetWorkaroundTimeMs = C.TIME_UNSET;
-      lastRawPlaybackHeadPosition = 0;
-      rawPlaybackHeadWrapCount = 0;
-      passthroughWorkaroundPauseOffset = 0;
-      if (audioTrack != null) {
-        sampleRate = audioTrack.getSampleRate();
-      }
-    }
-
-    /**
-     * Stops the audio track in a way that ensures media written to it is played out in full, and
-     * that {@link #getPlaybackHeadPosition()} and {@link #getPositionUs()} continue to increment as
-     * the remaining media is played out.
-     *
-     * @param writtenFrames The total number of frames that have been written.
-     */
-    public void handleEndOfStream(long writtenFrames) {
-      stopPlaybackHeadPosition = getPlaybackHeadPosition();
-      stopTimestampUs = SystemClock.elapsedRealtime() * 1000;
-      endPlaybackHeadPosition = writtenFrames;
-      audioTrack.stop();
-    }
-
-    /**
-     * Pauses the audio track unless the end of the stream has been handled, in which case calling
-     * this method does nothing.
-     */
-    public void pause() {
-      if (stopTimestampUs != C.TIME_UNSET) {
-        // We don't want to knock the audio track back into the paused state.
-        return;
-      }
-      audioTrack.pause();
-    }
-
-    /**
-     * Returns whether the track is in an invalid state and must be reset.
-     *
-     * @see #getPlaybackHeadPosition()
-     */
-    public boolean needsReset(long writtenFrames) {
-      return forceResetWorkaroundTimeMs != C.TIME_UNSET && writtenFrames > 0
-          && SystemClock.elapsedRealtime() - forceResetWorkaroundTimeMs
-              >= FORCE_RESET_WORKAROUND_TIMEOUT_MS;
-    }
-
-    /**
-     * {@link AudioTrack#getPlaybackHeadPosition()} returns a value intended to be interpreted as an
-     * unsigned 32 bit integer, which also wraps around periodically. This method returns the
-     * playback head position as a long that will only wrap around if the value exceeds
-     * {@link Long#MAX_VALUE} (which in practice will never happen).
-     *
-     * @return The playback head position, in frames.
-     */
-    public long getPlaybackHeadPosition() {
-      if (stopTimestampUs != C.TIME_UNSET) {
-        // Simulate the playback head position up to the total number of frames submitted.
-        long elapsedTimeSinceStopUs = (SystemClock.elapsedRealtime() * 1000) - stopTimestampUs;
-        long framesSinceStop = (elapsedTimeSinceStopUs * sampleRate) / C.MICROS_PER_SECOND;
-        return Math.min(endPlaybackHeadPosition, stopPlaybackHeadPosition + framesSinceStop);
-      }
-
-      @PlayState int playState = audioTrack.getPlayState();
-      if (playState == PLAYSTATE_STOPPED) {
-        // The audio track hasn't been started.
-        return 0;
-      }
-
-      long rawPlaybackHeadPosition = 0xFFFFFFFFL & audioTrack.getPlaybackHeadPosition();
-      if (needsPassthroughWorkaround) {
-        // Work around an issue with passthrough/direct AudioTracks on platform API versions 21/22
-        // where the playback head position jumps back to zero on paused passthrough/direct audio
-        // tracks. See [Internal: b/19187573].
-        if (playState == PLAYSTATE_PAUSED && rawPlaybackHeadPosition == 0) {
-          passthroughWorkaroundPauseOffset = lastRawPlaybackHeadPosition;
-        }
-        rawPlaybackHeadPosition += passthroughWorkaroundPauseOffset;
-      }
-
-      if (Util.SDK_INT <= 28) {
-        if (rawPlaybackHeadPosition == 0
-            && lastRawPlaybackHeadPosition > 0
-            && playState == PLAYSTATE_PLAYING) {
-          // If connecting a Bluetooth audio device fails, the AudioTrack may be left in a state
-          // where its Java API is in the playing state, but the native track is stopped. When this
-          // happens the playback head position gets stuck at zero. In this case, return the old
-          // playback head position and force the track to be reset after
-          // {@link #FORCE_RESET_WORKAROUND_TIMEOUT_MS} has elapsed.
-          if (forceResetWorkaroundTimeMs == C.TIME_UNSET) {
-            forceResetWorkaroundTimeMs = SystemClock.elapsedRealtime();
-          }
-          return lastRawPlaybackHeadPosition;
-        } else {
-          forceResetWorkaroundTimeMs = C.TIME_UNSET;
-        }
-      }
-
-      if (lastRawPlaybackHeadPosition > rawPlaybackHeadPosition) {
-        // The value must have wrapped around.
-        rawPlaybackHeadWrapCount++;
-      }
-      lastRawPlaybackHeadPosition = rawPlaybackHeadPosition;
-      return rawPlaybackHeadPosition + (rawPlaybackHeadWrapCount << 32);
-    }
-
-    /**
-     * Returns the duration of played media since reconfiguration, in microseconds.
-     */
-    public long getPositionUs() {
-      return (getPlaybackHeadPosition() * C.MICROS_PER_SECOND) / sampleRate;
-    }
-
-    /**
-     * Updates the values returned by {@link #getTimestampSystemTimeUs()} and {@link
-     * #getTimestampPositionFrames()}.
-     *
-     * @return Whether the timestamp values were updated.
-     */
-    public boolean updateTimestamp() {
-      return false;
-    }
-
-    /**
-     * Returns the system time in microseconds of the last {@link AudioTimestamp}, obtained during
-     * the most recent call to {@link #updateTimestamp()} that returned true.
-     *
-     * @return The system time in microseconds of the last {@link AudioTimestamp}, obtained during
-     *     the most recent call to {@link #updateTimestamp()} that returned true.
-     * @throws UnsupportedOperationException If the implementation does not support audio timestamp
-     *     queries. {@link #updateTimestamp()} will always return false in this case.
-     */
-    public long getTimestampSystemTimeUs() {
-      // Should never be called if updateTimestamp() returned false.
-      throw new UnsupportedOperationException();
-    }
-
-    /**
-     * Returns the position in frames of the last {@link AudioTimestamp}, obtained during the most
-     * recent call to {@link #updateTimestamp()} that returned true. The value is adjusted so that
-     * wrap around only occurs if the value exceeds {@link Long#MAX_VALUE} (which in practice will
-     * never happen).
-     *
-     * @return The position in frames of the last {@link AudioTimestamp}, obtained during the most
-     *     recent call to {@link #updateTimestamp()} that returned true.
-     * @throws UnsupportedOperationException If the implementation does not support audio timestamp
-     *     queries. {@link #updateTimestamp()} will always return false in this case.
-     */
-    public long getTimestampPositionFrames() {
-      // Should never be called if updateTimestamp() returned false.
-      throw new UnsupportedOperationException();
-    }
-
-  }
-
-  @TargetApi(19)
-  private static class AudioTrackUtilV19 extends AudioTrackUtil {
-
-    private final AudioTimestamp audioTimestamp;
-
-    private long rawTimestampPositionFramesWrapCount;
-    private long lastRawTimestampPositionFrames;
-    private long lastTimestampPositionFrames;
-
-    public AudioTrackUtilV19() {
-      audioTimestamp = new AudioTimestamp();
-    }
-
-    @Override
-    public void reconfigure(AudioTrack audioTrack, boolean needsPassthroughWorkaround) {
-      super.reconfigure(audioTrack, needsPassthroughWorkaround);
-      rawTimestampPositionFramesWrapCount = 0;
-      lastRawTimestampPositionFrames = 0;
-      lastTimestampPositionFrames = 0;
-    }
-
-    @Override
-    public boolean updateTimestamp() {
-      boolean updated = audioTrack.getTimestamp(audioTimestamp);
-      if (updated) {
-        long rawPositionFrames = audioTimestamp.framePosition;
-        if (lastRawTimestampPositionFrames > rawPositionFrames) {
-          // The value must have wrapped around.
-          rawTimestampPositionFramesWrapCount++;
-        }
-        lastRawTimestampPositionFrames = rawPositionFrames;
-        lastTimestampPositionFrames =
-            rawPositionFrames + (rawTimestampPositionFramesWrapCount << 32);
-      }
-      return updated;
-    }
-
-    @Override
-    public long getTimestampSystemTimeUs() {
-      return audioTimestamp.nanoTime / 1000;
-    }
-
-    @Override
-    public long getTimestampPositionFrames() {
-      return lastTimestampPositionFrames;
-    }
-
-  }
-
   /**
    * Stores playback parameters with the position and media time at which they apply.
    */
@@ -1600,64 +1129,7 @@ public final class DefaultAudioSink implements AudioSink {
 
   }
 
-  // TODO(b/74325207): Factor out position tracking functionality into a separate class.
+  private final class PositionTrackerListener implements AudioTrackPositionTracker.Listener {
-
-  /** Interface for errors relating to the audio track position. */
-  private interface AudioTrackPositionErrorListener {
-
-    /**
-     * Called when the frame position is too far from the expected frame position.
-     *
-     * @param audioTimestampPositionFrames The frame position of the last known audio track
-     *     timestamp.
-     * @param audioTimestampSystemTimeUs The system time associated with the last known audio track
-     *     timestamp, in microseconds.
-     * @param systemTimeUs The current time.
-     * @param playbackPositionUs The current playback head position in microseconds.
-     */
-    void onPositionFramesMismatch(
-        long audioTimestampPositionFrames,
-        long audioTimestampSystemTimeUs,
-        long systemTimeUs,
-        long playbackPositionUs);
-
-    /**
-     * Called when the system time associated with the last known audio track timestamp is
-     * unexpectedly far from the current time.
-     *
-     * @param audioTimestampPositionFrames The frame position of the last known audio track
-     *     timestamp.
-     * @param audioTimestampSystemTimeUs The system time associated with the last known audio track
-     *     timestamp, in microseconds.
-     * @param systemTimeUs The current time.
-     * @param playbackPositionUs The current playback head position in microseconds.
-     */
-    void onSystemTimeUsMismatch(
-        long audioTimestampPositionFrames,
-        long audioTimestampSystemTimeUs,
-        long systemTimeUs,
-        long playbackPositionUs);
-
-    /**
-     * Called when the audio track has provided an invalid latency.
-     *
-     * @param latencyUs The reported latency in microseconds.
-     */
-    void onInvalidLatency(long latencyUs);
-
-    /**
-     * Called if the audio track runs out of data to play.
-     *
-     * @param bufferSize The size of the sink's buffer, in bytes.
-     * @param bufferSizeMs The size of the sink's buffer, in milliseconds, if it is configured for
-     *     PCM output. {@link C#TIME_UNSET} if it is configured for encoded audio output, as the
-     *     buffered media can have a variable bitrate so the duration may be unknown.
-     */
-    void onUnderrun(int bufferSize, long bufferSizeMs);
-  }
-
-  private final class DefaultAudioTrackPositionErrorListener
-      implements AudioTrackPositionErrorListener {
 
     @Override
     public void onPositionFramesMismatch(