Parse the sequence number at discontinuities.

This is required to match up segments in one playlist (e.g. VTT)
to those in another (e.g. Audio/Video).

library/src/androidTest/java/com/google/android/exoplayer/hls/HlsMediaPlaylistParserTest.java

@@ -37,6 +37,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
         + "#EXT-X-VERSION:3\n"
         + "#EXT-X-TARGETDURATION:8\n"
         + "#EXT-X-MEDIA-SEQUENCE:2679\n"
+        + "#EXT-X-DISCONTINUITY-SEQUENCE:4\n"
         + "#EXT-X-ALLOW-CACHE:YES\n"
         + "\n"
         + "#EXTINF:7.975,\n"
@@ -79,7 +80,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
       assertNotNull(segments);
       assertEquals(5, segments.size());
 
-      assertEquals(false, segments.get(0).discontinuity);
+      assertEquals(4, segments.get(0).discontinuitySequenceNumber);
       assertEquals(7.975, segments.get(0).durationSecs);
       assertEquals(false, segments.get(0).isEncrypted);
       assertEquals(null, segments.get(0).encryptionKeyUri);
@@ -88,7 +89,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
       assertEquals(0, segments.get(0).byterangeOffset);
       assertEquals("https://priv.example.com/fileSequence2679.ts", segments.get(0).url);
 
-      assertEquals(false, segments.get(1).discontinuity);
+      assertEquals(4, segments.get(1).discontinuitySequenceNumber);
       assertEquals(7.975, segments.get(1).durationSecs);
       assertEquals(true, segments.get(1).isEncrypted);
       assertEquals("https://priv.example.com/key.php?r=2680", segments.get(1).encryptionKeyUri);
@@ -97,7 +98,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
       assertEquals(51370, segments.get(1).byterangeOffset);
       assertEquals("https://priv.example.com/fileSequence2680.ts", segments.get(1).url);
 
-      assertEquals(false, segments.get(2).discontinuity);
+      assertEquals(4, segments.get(2).discontinuitySequenceNumber);
       assertEquals(7.941, segments.get(2).durationSecs);
       assertEquals(false, segments.get(2).isEncrypted);
       assertEquals(null, segments.get(2).encryptionKeyUri);
@@ -106,7 +107,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
       assertEquals(102871, segments.get(2).byterangeOffset);
       assertEquals("https://priv.example.com/fileSequence2681.ts", segments.get(2).url);
 
-      assertEquals(true, segments.get(3).discontinuity);
+      assertEquals(5, segments.get(3).discontinuitySequenceNumber);
       assertEquals(7.975, segments.get(3).durationSecs);
       assertEquals(true, segments.get(3).isEncrypted);
       assertEquals("https://priv.example.com/key.php?r=2682", segments.get(3).encryptionKeyUri);
@@ -117,7 +118,7 @@ public class HlsMediaPlaylistParserTest extends TestCase {
       assertEquals(154372, segments.get(3).byterangeOffset);
       assertEquals("https://priv.example.com/fileSequence2682.ts", segments.get(3).url);
 
-      assertEquals(false, segments.get(4).discontinuity);
+      assertEquals(5, segments.get(4).discontinuitySequenceNumber);
       assertEquals(7.975, segments.get(4).durationSecs);
       assertEquals(true, segments.get(4).isEncrypted);
       assertEquals("https://priv.example.com/key.php?r=2682", segments.get(4).encryptionKeyUri);

library/src/main/java/com/google/android/exoplayer/hls/HlsChunkSource.java

@@ -364,10 +364,12 @@ public class HlsChunkSource {
       Extractor extractor = new Mp3Extractor(startTimeUs);
       extractorWrapper = new HlsExtractorWrapper(trigger, format, startTimeUs, extractor,
           switchingVariantSpliced, adaptiveMaxWidth, adaptiveMaxHeight);
-    } else if (previousTsChunk == null || segment.discontinuity || liveDiscontinuity
+    } else if (previousTsChunk == null || liveDiscontinuity
+        || previousTsChunk.discontinuitySequenceNumber != segment.discontinuitySequenceNumber
         || !format.equals(previousTsChunk.format)) {
       // MPEG-2 TS segments, but we need a new extractor.
-      if (previousTsChunk == null || segment.discontinuity || liveDiscontinuity
+      if (previousTsChunk == null || liveDiscontinuity
+          || previousTsChunk.discontinuitySequenceNumber != segment.discontinuitySequenceNumber
           || ptsTimestampAdjuster == null) {
         // TODO: Use this for AAC as well, along with the ID3 PRIV priv tag values with owner
         // identifier com.apple.streaming.transportStreamTimestamp.
@@ -382,7 +384,8 @@ public class HlsChunkSource {
     }
 
     out.chunk = new TsChunk(dataSource, dataSpec, trigger, format, startTimeUs, endTimeUs,
-        chunkMediaSequence, extractorWrapper, encryptionKey, encryptionIv);
+        chunkMediaSequence, segment.discontinuitySequenceNumber, extractorWrapper, encryptionKey,
+        encryptionIv);
   }
 
   /**

library/src/main/java/com/google/android/exoplayer/hls/HlsMediaPlaylist.java

@@ -29,9 +29,9 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
    */
   public static final class Segment implements Comparable<Long> {
 
-    public final boolean discontinuity;
-    public final double durationSecs;
     public final String url;
+    public final double durationSecs;
+    public final int discontinuitySequenceNumber;
     public final long startTimeUs;
     public final boolean isEncrypted;
     public final String encryptionKeyUri;
@@ -39,12 +39,12 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
     public final int byterangeOffset;
     public final int byterangeLength;
 
-    public Segment(String uri, double durationSecs, boolean discontinuity, long startTimeUs,
+    public Segment(String uri, double durationSecs, int discontinuitySequenceNumber,
-        boolean isEncrypted, String encryptionKeyUri, String encryptionIV, int byterangeOffset,
+        long startTimeUs, boolean isEncrypted, String encryptionKeyUri, String encryptionIV,
-        int byterangeLength) {
+        int byterangeOffset, int byterangeLength) {
       this.url = uri;
       this.durationSecs = durationSecs;
-      this.discontinuity = discontinuity;
+      this.discontinuitySequenceNumber = discontinuitySequenceNumber;
       this.startTimeUs = startTimeUs;
       this.isEncrypted = isEncrypted;
       this.encryptionKeyUri = encryptionKeyUri;

library/src/main/java/com/google/android/exoplayer/hls/HlsPlaylistParser.java

@@ -40,6 +40,7 @@ public final class HlsPlaylistParser implements UriLoadable.Parser<HlsPlaylist>
   private static final String STREAM_INF_TAG = "#EXT-X-STREAM-INF";
   private static final String MEDIA_TAG = "#EXT-X-MEDIA";
   private static final String DISCONTINUITY_TAG = "#EXT-X-DISCONTINUITY";
+  private static final String DISCONTINUITY_SEQUENCE_TAG = "#EXT-X-DISCONTINUITY-SEQUENCE";
   private static final String MEDIA_DURATION_TAG = "#EXTINF";
   private static final String MEDIA_SEQUENCE_TAG = "#EXT-X-MEDIA-SEQUENCE";
   private static final String TARGET_DURATION_TAG = "#EXT-X-TARGETDURATION";
@@ -122,6 +123,7 @@ public final class HlsPlaylistParser implements UriLoadable.Parser<HlsPlaylist>
             || line.startsWith(KEY_TAG)
             || line.startsWith(BYTERANGE_TAG)
             || line.equals(DISCONTINUITY_TAG)
+            || line.equals(DISCONTINUITY_SEQUENCE_TAG)
             || line.equals(ENDLIST_TAG)) {
           extraLines.add(line);
           return parseMediaPlaylist(new LineIterator(extraLines, reader), connectionUrl);
@@ -208,7 +210,7 @@ public final class HlsPlaylistParser implements UriLoadable.Parser<HlsPlaylist>
     List<Segment> segments = new ArrayList<>();
 
     double segmentDurationSecs = 0.0;
-    boolean segmentDiscontinuity = false;
+    int discontinuitySequenceNumber = 0;
     long segmentStartTimeUs = 0;
     int segmentByterangeOffset = 0;
     int segmentByterangeLength = C.LENGTH_UNBOUNDED;
@@ -249,8 +251,10 @@ public final class HlsPlaylistParser implements UriLoadable.Parser<HlsPlaylist>
         if (splitByteRange.length > 1) {
           segmentByterangeOffset = Integer.parseInt(splitByteRange[1]);
         }
+      } else if (line.startsWith(DISCONTINUITY_SEQUENCE_TAG)) {
+        discontinuitySequenceNumber = Integer.parseInt(line.substring(line.indexOf(':') + 1));
       } else if (line.equals(DISCONTINUITY_TAG)) {
-        segmentDiscontinuity = true;
+        discontinuitySequenceNumber++;
       } else if (!line.startsWith("#")) {
         String segmentEncryptionIV;
         if (!isEncrypted) {
@@ -264,11 +268,10 @@ public final class HlsPlaylistParser implements UriLoadable.Parser<HlsPlaylist>
         if (segmentByterangeLength == C.LENGTH_UNBOUNDED) {
           segmentByterangeOffset = 0;
         }
-        segments.add(new Segment(line, segmentDurationSecs, segmentDiscontinuity,
+        segments.add(new Segment(line, segmentDurationSecs, discontinuitySequenceNumber,
             segmentStartTimeUs, isEncrypted, encryptionKeyUri, segmentEncryptionIV,
             segmentByterangeOffset, segmentByterangeLength));
         segmentStartTimeUs += (long) (segmentDurationSecs * C.MICROS_PER_SECOND);
-        segmentDiscontinuity = false;
         segmentDurationSecs = 0.0;
         if (segmentByterangeLength != C.LENGTH_UNBOUNDED) {
           segmentByterangeOffset += segmentByterangeLength;

library/src/main/java/com/google/android/exoplayer/hls/TsChunk.java

@@ -31,6 +31,11 @@ import java.io.IOException;
  */
 public final class TsChunk extends MediaChunk {
 
+  /**
+   * The discontinuity sequence number of the chunk.
+   */
+  public final int discontinuitySequenceNumber;
+
   /**
    * The wrapped extractor into which this chunk is being consumed.
    */
@@ -48,16 +53,18 @@ public final class TsChunk extends MediaChunk {
    * @param format The format of the stream to which this chunk belongs.
    * @param startTimeUs The start time of the media contained by the chunk, in microseconds.
    * @param endTimeUs The end time of the media contained by the chunk, in microseconds.
+   * @param discontinuitySequenceNumber The discontinuity sequence number of the chunk.
    * @param chunkIndex The index of the chunk.
    * @param extractorWrapper A wrapped extractor to parse samples from the data.
    * @param encryptionKey For AES encryption chunks, the encryption key.
    * @param encryptionIv For AES encryption chunks, the encryption initialization vector.
    */
   public TsChunk(DataSource dataSource, DataSpec dataSpec, int trigger, Format format,
-      long startTimeUs, long endTimeUs, int chunkIndex, HlsExtractorWrapper extractorWrapper,
+      long startTimeUs, long endTimeUs, int chunkIndex, int discontinuitySequenceNumber,
-      byte[] encryptionKey, byte[] encryptionIv) {
+      HlsExtractorWrapper extractorWrapper, byte[] encryptionKey, byte[] encryptionIv) {
     super(buildDataSource(dataSource, encryptionKey, encryptionIv), dataSpec, trigger, format,
         startTimeUs, endTimeUs, chunkIndex);
+    this.discontinuitySequenceNumber = discontinuitySequenceNumber;
     this.extractorWrapper = extractorWrapper;
     // Note: this.dataSource and dataSource may be different.
     this.isEncrypted = this.dataSource instanceof Aes128DataSource;