From ee0c6224af554bd076fcc91bc7d7b7d1cf7853d5 Mon Sep 17 00:00:00 2001
From: ibaker <ibaker@google.com>
Date: Fri, 5 Jun 2020 14:42:47 +0100
Subject: [PATCH] Respect 33-bit wraparound when calculating WebVTT timestamps
 in HLS

Issue: #7462
PiperOrigin-RevId: 314919210
---
 RELEASENOTES.md                               |  2 ++
 .../exoplayer2/util/TimestampAdjuster.java    | 19 ++++++++++++++++---
 .../scte35/SpliceInfoDecoderTest.java         |  3 ++-
 .../source/hls/WebvttExtractor.java           |  5 +++--
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index fc0eacab2e..ce8541ed1e 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -157,6 +157,8 @@
 *   HLS:
     *   Add support for upstream discard including cancelation of ongoing load
         ([#6322](https://github.com/google/ExoPlayer/issues/6322)).
+    *   Respect 33-bit PTS wrapping when applying `X-TIMESTAMP-MAP` to WebVTT
+        timestamps ([#7464](https://github.com/google/ExoPlayer/issues/7464)).
 *   Ogg: Allow non-contiguous pages
     ([#7230](https://github.com/google/ExoPlayer/issues/7230)).
 *   Extractors:
diff --git a/library/common/src/main/java/com/google/android/exoplayer2/util/TimestampAdjuster.java b/library/common/src/main/java/com/google/android/exoplayer2/util/TimestampAdjuster.java
index 439374a086..65f88b1983 100644
--- a/library/common/src/main/java/com/google/android/exoplayer2/util/TimestampAdjuster.java
+++ b/library/common/src/main/java/com/google/android/exoplayer2/util/TimestampAdjuster.java
@@ -113,7 +113,7 @@ public final class TimestampAdjuster {
     if (lastSampleTimestampUs != C.TIME_UNSET) {
       // The wrap count for the current PTS may be closestWrapCount or (closestWrapCount - 1),
       // and we need to snap to the one closest to lastSampleTimestampUs.
-      long lastPts = usToPts(lastSampleTimestampUs);
+      long lastPts = usToNonWrappedPts(lastSampleTimestampUs);
       long closestWrapCount = (lastPts + (MAX_PTS_PLUS_ONE / 2)) / MAX_PTS_PLUS_ONE;
       long ptsWrapBelow = pts90Khz + (MAX_PTS_PLUS_ONE * (closestWrapCount - 1));
       long ptsWrapAbove = pts90Khz + (MAX_PTS_PLUS_ONE * closestWrapCount);
@@ -173,14 +173,27 @@ public final class TimestampAdjuster {
     return (pts * C.MICROS_PER_SECOND) / 90000;
   }
 
+  /**
+   * Converts a timestamp in microseconds to a 90 kHz clock timestamp, performing wraparound to keep
+   * the result within 33-bits.
+   *
+   * @param us A value in microseconds.
+   * @return The corresponding value as a 90 kHz clock timestamp, wrapped to 33 bits.
+   */
+  public static long usToWrappedPts(long us) {
+    return usToNonWrappedPts(us) % MAX_PTS_PLUS_ONE;
+  }
+
   /**
    * Converts a timestamp in microseconds to a 90 kHz clock timestamp.
    *
+   * <p>Does not perform any wraparound. To get a 90 kHz timestamp suitable for use with MPEG-TS,
+   * use {@link #usToWrappedPts(long)}.
+   *
    * @param us A value in microseconds.
    * @return The corresponding value as a 90 kHz clock timestamp.
    */
-  public static long usToPts(long us) {
+  public static long usToNonWrappedPts(long us) {
     return (us * 90000) / C.MICROS_PER_SECOND;
   }
-
 }
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/metadata/scte35/SpliceInfoDecoderTest.java b/library/core/src/test/java/com/google/android/exoplayer2/metadata/scte35/SpliceInfoDecoderTest.java
index 90c2e7d386..dcb1f634c9 100644
--- a/library/core/src/test/java/com/google/android/exoplayer2/metadata/scte35/SpliceInfoDecoderTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/metadata/scte35/SpliceInfoDecoderTest.java
@@ -200,7 +200,8 @@ public final class SpliceInfoDecoderTest {
   }
 
   private static long removePtsConversionPrecisionError(long timeUs, long offsetUs) {
-    return TimestampAdjuster.ptsToUs(TimestampAdjuster.usToPts(timeUs - offsetUs)) + offsetUs;
+    return TimestampAdjuster.ptsToUs(TimestampAdjuster.usToNonWrappedPts(timeUs - offsetUs))
+        + offsetUs;
   }
 
 }
diff --git a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/WebvttExtractor.java b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/WebvttExtractor.java
index 6a390001d2..832de00cf9 100644
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/WebvttExtractor.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/WebvttExtractor.java
@@ -176,8 +176,9 @@ public final class WebvttExtractor implements Extractor {
 
     long firstCueTimeUs =
         WebvttParserUtil.parseTimestampUs(Assertions.checkNotNull(cueHeaderMatcher.group(1)));
-    long sampleTimeUs = timestampAdjuster.adjustTsTimestamp(
-        TimestampAdjuster.usToPts(firstCueTimeUs + tsTimestampUs - vttTimestampUs));
+    long sampleTimeUs =
+        timestampAdjuster.adjustTsTimestamp(
+            TimestampAdjuster.usToWrappedPts(firstCueTimeUs + tsTimestampUs - vttTimestampUs));
     long subsampleOffsetUs = sampleTimeUs - firstCueTimeUs;
     // Output the track.
     TrackOutput trackOutput = buildTrackOutput(subsampleOffsetUs);