From ace97facf2c0fea5edc14858a36f0099724ce61f Mon Sep 17 00:00:00 2001
From: michaelkatz <michaelkatz@google.com>
Date: Fri, 27 Jan 2023 11:25:33 +0000
Subject: [PATCH] Match MergingMediaPeriod track selection by period index in
 id

MergingMediaPeriod creates its track groups with ids concatenating position in its periods array and the underlying child track group id. The ids can be used in selectTracks for matching to periods list.

Issue: google/ExoPlayer#10930
PiperOrigin-RevId: 505074653
(cherry picked from commit ee055ef004686ddb3844666f9506a95c6e16a59f)
---
 .../exoplayer2/source/MergingMediaPeriod.java | 14 +++-----
 .../source/MergingMediaPeriodTest.java        | 33 +++++++++++++++++++
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java b/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
index 09eec4815a..8f056fc094 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
@@ -117,17 +117,13 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     for (int i = 0; i < selections.length; i++) {
       Integer streamChildIndex = streams[i] == null ? null : streamPeriodIndices.get(streams[i]);
       streamChildIndices[i] = streamChildIndex == null ? C.INDEX_UNSET : streamChildIndex;
-      selectionChildIndices[i] = C.INDEX_UNSET;
       if (selections[i] != null) {
         TrackGroup mergedTrackGroup = selections[i].getTrackGroup();
-        TrackGroup childTrackGroup =
-            checkNotNull(childTrackGroupByMergedTrackGroup.get(mergedTrackGroup));
-        for (int j = 0; j < periods.length; j++) {
-          if (periods[j].getTrackGroups().indexOf(childTrackGroup) != C.INDEX_UNSET) {
-            selectionChildIndices[i] = j;
-            break;
-          }
-        }
+        // mergedTrackGroup.id is 'periods array index' + ":" + childTrackGroup.id
+        selectionChildIndices[i] =
+            Integer.parseInt(mergedTrackGroup.id.substring(0, mergedTrackGroup.id.indexOf(":")));
+      } else {
+        selectionChildIndices[i] = C.INDEX_UNSET;
       }
     }
     streamPeriodIndices.clear();
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/source/MergingMediaPeriodTest.java b/library/core/src/test/java/com/google/android/exoplayer2/source/MergingMediaPeriodTest.java
index ee5425c7b9..be0d8848d7 100644
--- a/library/core/src/test/java/com/google/android/exoplayer2/source/MergingMediaPeriodTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/source/MergingMediaPeriodTest.java
@@ -197,6 +197,39 @@ public final class MergingMediaPeriodTest {
     assertThat(firstSelectionChild2).isEqualTo(secondSelectionChild2);
   }
 
+  // https://github.com/google/ExoPlayer/issues/10930
+  @Test
+  public void selectTracks_withIdenticalFormats_selectsMatchingPeriod() throws Exception {
+    MergingMediaPeriod mergingMediaPeriod =
+        prepareMergingPeriod(
+            new MergingPeriodDefinition(
+                /* timeOffsetUs= */ 0, /* singleSampleTimeUs= */ 123_000, childFormat11),
+            new MergingPeriodDefinition(
+                /* timeOffsetUs= */ -3000, /* singleSampleTimeUs= */ 456_000, childFormat11));
+
+    ExoTrackSelection[] selectionArray = {
+      new FixedTrackSelection(mergingMediaPeriod.getTrackGroups().get(1), /* track= */ 0)
+    };
+
+    SampleStream[] streams = new SampleStream[1];
+    mergingMediaPeriod.selectTracks(
+        selectionArray,
+        /* mayRetainStreamFlags= */ new boolean[2],
+        streams,
+        /* streamResetFlags= */ new boolean[2],
+        /* positionUs= */ 0);
+    mergingMediaPeriod.continueLoading(/* positionUs= */ 0);
+
+    FormatHolder formatHolder = new FormatHolder();
+    DecoderInputBuffer inputBuffer =
+        new DecoderInputBuffer(DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_NORMAL);
+    streams[0].readData(formatHolder, inputBuffer, FLAG_REQUIRE_FORMAT);
+
+    assertThat(streams[0].readData(formatHolder, inputBuffer, /* readFlags= */ 0))
+        .isEqualTo(C.RESULT_BUFFER_READ);
+    assertThat(inputBuffer.timeUs).isEqualTo(456_000 - 3000);
+  }
+
   private MergingMediaPeriod prepareMergingPeriod(MergingPeriodDefinition... definitions)
       throws Exception {
     MediaPeriod[] mediaPeriods = new MediaPeriod[definitions.length];