From 68add98c239e23d1fb05fc2c70ee3624f5b1004f Mon Sep 17 00:00:00 2001
From: andrewlewis <andrewlewis@google.com>
Date: Mon, 30 Jul 2018 07:01:18 -0700
Subject: [PATCH] Fix detection of TrueHD syncframe in MatroskaExtractor

MatroskaExtractor was checking for INDEX_UNSET as the sample count for buffers
not containing syncframes, but actually 0 was returned for these. Theoretically
this could prevent us starting to play a TrueHD stream as we wait until we can
read the sample count from a syncframe before accepting the audio in
DefaultAudioSink, but it seems that rechunking avoided this issue arising in
practice.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=206575462
---
 .../extractor/mkv/MatroskaExtractor.java      |  2 +-
 .../android/exoplayer2/audio/Ac3UtilTest.java | 46 +++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 library/core/src/test/java/com/google/android/exoplayer2/audio/Ac3UtilTest.java

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java
index 5ff52a39d1..32d906e535 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java
@@ -1551,7 +1551,7 @@ public final class MatroskaExtractor implements Extractor {
       if (!foundSyncframe) {
         input.peekFully(syncframePrefix, 0, Ac3Util.TRUEHD_SYNCFRAME_PREFIX_LENGTH);
         input.resetPeekPosition();
-        if ((Ac3Util.parseTrueHdSyncframeAudioSampleCount(syncframePrefix) == C.INDEX_UNSET)) {
+        if ((Ac3Util.parseTrueHdSyncframeAudioSampleCount(syncframePrefix) == 0)) {
           return;
         }
         foundSyncframe = true;
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/audio/Ac3UtilTest.java b/library/core/src/test/java/com/google/android/exoplayer2/audio/Ac3UtilTest.java
new file mode 100644
index 0000000000..e41e270966
--- /dev/null
+++ b/library/core/src/test/java/com/google/android/exoplayer2/audio/Ac3UtilTest.java
@@ -0,0 +1,46 @@
+/*
+ * 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 static com.google.common.truth.Truth.assertThat;
+
+import com.google.android.exoplayer2.util.Util;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+/** Unit tests for {@link Ac3Util}. */
+@RunWith(RobolectricTestRunner.class)
+public final class Ac3UtilTest {
+
+  private static final int TRUEHD_SYNCFRAME_SAMPLE_COUNT = 40;
+  private static final byte[] TRUEHD_SYNCFRAME_HEADER =
+      Util.getBytesFromHexString("C07504D8F8726FBA0097C00FB7520000");
+  private static final byte[] TRUEHD_NON_SYNCFRAME_HEADER =
+      Util.getBytesFromHexString("A025048860224E6F6DEDB6D5B6DBAFE6");
+
+  @Test
+  public void testParseTrueHdSyncframeAudioSampleCount_nonSyncframe() {
+    assertThat(Ac3Util.parseTrueHdSyncframeAudioSampleCount(TRUEHD_NON_SYNCFRAME_HEADER))
+        .isEqualTo(0);
+  }
+
+  @Test
+  public void testParseTrueHdSyncframeAudioSampleCount_syncframe() {
+    assertThat(Ac3Util.parseTrueHdSyncframeAudioSampleCount(TRUEHD_SYNCFRAME_HEADER))
+        .isEqualTo(TRUEHD_SYNCFRAME_SAMPLE_COUNT);
+  }
+}