Expose ability to get adjusted seek position from MediaPeriod

Issue: #2882

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=178606133

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -660,11 +660,19 @@ import java.io.IOException;
       periodPositionUs = 0;
     }
     try {
-      if (periodId.equals(playbackInfo.periodId)
+      if (periodId.equals(playbackInfo.periodId)) {
-          && ((periodPositionUs / 1000) == (playbackInfo.positionUs / 1000))) {
+        long adjustedPeriodPositionUs = periodPositionUs;
-        // Seek position equals the current position. Do nothing.
+        if (playingPeriodHolder != null) {
+          adjustedPeriodPositionUs =
+              playingPeriodHolder.mediaPeriod.getAdjustedSeekPositionUs(
+                  adjustedPeriodPositionUs, SeekParameters.DEFAULT);
+        }
+        if ((adjustedPeriodPositionUs / 1000) == (playbackInfo.positionUs / 1000)) {
+          // Seek will be performed to the current position. Do nothing.
+          periodPositionUs = playbackInfo.positionUs;
           return;
         }
+      }
       long newPeriodPositionUs = seekToPeriodPosition(periodId, periodPositionUs);
       seekPositionAdjusted |= periodPositionUs != newPeriodPositionUs;
       periodPositionUs = newPeriodPositionUs;

library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaPeriod.java

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.source;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.util.Assertions;
@@ -170,6 +171,12 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     return seekUs - startUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return mediaPeriod.getAdjustedSeekPositionUs(
+        positionUs + startUs, adjustSeekParameters(positionUs + startUs, seekParameters));
+  }
+
   @Override
   public long getNextLoadPositionUs() {
     long nextLoadPositionUs = mediaPeriod.getNextLoadPositionUs();
@@ -202,6 +209,20 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     return pendingInitialDiscontinuityPositionUs != C.TIME_UNSET;
   }
 
+  private SeekParameters adjustSeekParameters(long positionUs, SeekParameters seekParameters) {
+    long toleranceBeforeMs = Math.min(positionUs - startUs, seekParameters.toleranceBeforeUs);
+    long toleranceAfterMs =
+        endUs == C.TIME_END_OF_SOURCE
+            ? seekParameters.toleranceAfterUs
+            : Math.min(endUs - positionUs, seekParameters.toleranceAfterUs);
+    if (toleranceBeforeMs == seekParameters.toleranceBeforeUs
+        && toleranceAfterMs == seekParameters.toleranceAfterUs) {
+      return seekParameters;
+    } else {
+      return new SeekParameters(toleranceBeforeMs, toleranceAfterMs);
+    }
+  }
+
   private static boolean shouldKeepInitialDiscontinuity(long startUs, TrackSelection[] selections) {
     // If the clipping start position is non-zero, the clipping sample streams will adjust
     // timestamps on buffers they read from the unclipped sample streams. These adjusted buffer

library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.source.MediaSource.MediaPeriodId;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
@@ -114,6 +115,11 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     return mediaPeriod.seekToUs(positionUs);
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return mediaPeriod.getAdjustedSeekPositionUs(positionUs, seekParameters);
+  }
+
   @Override
   public long getNextLoadPositionUs() {
     return mediaPeriod.getNextLoadPositionUs();

library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaPeriod.java

@@ -21,6 +21,7 @@ import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.extractor.DefaultExtractorInput;
 import com.google.android.exoplayer2.extractor.Extractor;
@@ -369,6 +370,12 @@ import java.util.Arrays;
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    // Treat all seeks into non-seekable media as being to t=0.
+    return seekMap.isSeekable() ? positionUs : 0;
+  }
+
   // SampleStream methods.
 
   /* package */ boolean isReady(int track) {

library/core/src/main/java/com/google/android/exoplayer2/source/MediaPeriod.java

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.source;
 
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayer;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import java.io.IOException;
@@ -149,6 +150,19 @@ public interface MediaPeriod extends SequenceableLoader {
    */
   long seekToUs(long positionUs);
 
+  /**
+   * Returns the position to which a seek will be performed, given the specified seek position and
+   * {@link SeekParameters}.
+   *
+   * <p>This method should only be called after the period has been prepared.
+   *
+   * @param positionUs The seek position in microseconds.
+   * @param seekParameters Parameters that control how the seek is performed. Implementations may
+   *     apply seek parameters on a best effort basis.
+   * @return The actual position to which a seek will be performed, in microseconds.
+   */
+  long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters);
+
   // SequenceableLoader interface. Overridden to provide more specific documentation.
 
   /**

library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.source;
 
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.IOException;
@@ -192,6 +193,11 @@ import java.util.IdentityHashMap;
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return enabledPeriods[0].getAdjustedSeekPositionUs(positionUs, seekParameters);
+  }
+
   // MediaPeriod.Callback implementation
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaPeriod.java

@@ -20,6 +20,7 @@ import android.os.Handler;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.source.SingleSampleMediaSource.EventListener;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
@@ -153,11 +154,16 @@ import java.util.Arrays;
   @Override
   public long seekToUs(long positionUs) {
     for (int i = 0; i < sampleStreams.size(); i++) {
-      sampleStreams.get(i).seekToUs(positionUs);
+      sampleStreams.get(i).reset();
     }
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return positionUs;
+  }
+
   // Loader.Callback implementation.
 
   @Override
@@ -208,7 +214,7 @@ import java.util.Arrays;
 
     private int streamState;
 
-    public void seekToUs(long positionUs) {
+    public void reset() {
       if (streamState == STREAM_STATE_END_OF_STREAM) {
         streamState = STREAM_STATE_SEND_SAMPLE;
       }

library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaPeriod.java

@@ -20,6 +20,7 @@ import android.util.Pair;
 import android.util.SparseIntArray;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.source.CompositeSequenceableLoaderFactory;
 import com.google.android.exoplayer2.source.EmptySampleStream;
 import com.google.android.exoplayer2.source.MediaPeriod;
@@ -306,6 +307,11 @@ import java.util.Map;
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return positionUs;
+  }
+
   // SequenceableLoader.Callback implementation.
 
   @Override

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaPeriod.java

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.source.hls;
 import android.os.Handler;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.source.CompositeSequenceableLoaderFactory;
 import com.google.android.exoplayer2.source.MediaPeriod;
 import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
@@ -244,6 +245,11 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return positionUs;
+  }
+
   // HlsSampleStreamWrapper.Callback implementation.
 
   @Override

library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaPeriod.java

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.source.smoothstreaming;
 
 import android.util.Base64;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.extractor.mp4.TrackEncryptionBox;
 import com.google.android.exoplayer2.source.CompositeSequenceableLoaderFactory;
 import com.google.android.exoplayer2.source.MediaPeriod;
@@ -182,6 +183,11 @@ import java.util.ArrayList;
     return positionUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return positionUs;
+  }
+
   // SequenceableLoader.Callback implementation
 
   @Override

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaPeriod.java

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.testutil;
 import android.os.Handler;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.source.MediaPeriod;
 import com.google.android.exoplayer2.source.SampleStream;
 import com.google.android.exoplayer2.source.TrackGroup;
@@ -176,6 +177,11 @@ public class FakeMediaPeriod implements MediaPeriod {
     return positionUs + seekOffsetUs;
   }
 
+  @Override
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return positionUs;
+  }
+
   @Override
   public long getNextLoadPositionUs() {
     Assert.assertTrue(prepared);

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeSimpleExoPlayer.java

@@ -422,8 +422,12 @@ public class FakeSimpleExoPlayer extends SimpleExoPlayer {
       SampleStream[] sampleStreams = new SampleStream[renderers.length];
       boolean[] mayRetainStreamFlags = new boolean[renderers.length];
       Arrays.fill(mayRetainStreamFlags, true);
-      mediaPeriod.selectTracks(selectorResult.selections.getAll(), mayRetainStreamFlags,
+      mediaPeriod.selectTracks(
-          sampleStreams, new boolean[renderers.length], 0);
+          selectorResult.selections.getAll(),
+          mayRetainStreamFlags,
+          sampleStreams,
+          new boolean[renderers.length],
+          /* positionUs = */ 0);
       eventListenerHandler.post(new Runnable() {
         @Override
         public void run() {