Parse CHANNELS attribute from EXT-X-MEDIA

PiperOrigin-RevId: 230743198

RELEASENOTES.md

@@ -2,7 +2,8 @@
 
 ### dev-v2 (not yet released) ###
 
-* Increase `minSdkVersion` to 16 (Jellybean).
+* HLS:
+  * Parse CHANNELS attribute from EXT-X-MEDIA.
 * Support for playing spherical videos on Daydream.
 * Improve decoder re-use between playbacks. TODO: Write and link a blog post
   here ([#2826](https://github.com/google/ExoPlayer/issues/2826)).

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

@@ -101,6 +101,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
       Pattern.compile("AVERAGE-BANDWIDTH=(\\d+)\\b");
   private static final Pattern REGEX_AUDIO = Pattern.compile("AUDIO=\"(.+?)\"");
   private static final Pattern REGEX_BANDWIDTH = Pattern.compile("[^-]BANDWIDTH=(\\d+)\\b");
+  private static final Pattern REGEX_CHANNELS = Pattern.compile("CHANNELS=\"(.+?)\"");
   private static final Pattern REGEX_CODECS = Pattern.compile("CODECS=\"(.+?)\"");
   private static final Pattern REGEX_RESOLUTION = Pattern.compile("RESOLUTION=(\\d+x\\d+)");
   private static final Pattern REGEX_FRAME_RATE = Pattern.compile("FRAME-RATE=([\\d\\.]+)\\b");
@@ -346,6 +347,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
       switch (parseStringAttr(line, REGEX_TYPE, variableDefinitions)) {
         case TYPE_AUDIO:
           String codecs = audioGroupIdToCodecs.get(groupId);
+          int channelCount = parseChannelsAttribute(line, variableDefinitions);
           String sampleMimeType = codecs != null ? MimeTypes.getMediaMimeType(codecs) : null;
           format =
               Format.createAudioContainerFormat(
@@ -355,7 +357,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
                   sampleMimeType,
                   codecs,
                   /* bitrate= */ Format.NO_VALUE,
-                  /* channelCount= */ Format.NO_VALUE,
+                  channelCount,
                   /* sampleRate= */ Format.NO_VALUE,
                   /* initializationData= */ null,
                   selectionFlags,
@@ -661,6 +663,13 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     return flags;
   }
 
+  private static int parseChannelsAttribute(String line, Map<String, String> variableDefinitions) {
+    String channelsString = parseOptionalStringAttr(line, REGEX_CHANNELS, variableDefinitions);
+    return channelsString != null
+        ? Integer.parseInt(Util.splitAtFirst(channelsString, "/")[0])
+        : Format.NO_VALUE;
+  }
+
   private static @Nullable SchemeData parsePlayReadySchemeData(
       String line, Map<String, String> variableDefinitions) throws ParserException {
     String keyFormatVersions =

library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMasterPlaylistParserTest.java

@@ -81,6 +81,18 @@ public class HlsMasterPlaylistParserTest {
           + "CODECS=\"mp4a.40.2,avc1.66.30\",RESOLUTION=304x128\n"
           + "http://example.com/low.m3u8\n";
 
+  private static final String PLAYLIST_WITH_CHANNELS_ATTRIBUTE =
+      " #EXTM3U \n"
+          + "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audio\",CHANNELS=\"6\",NAME=\"Eng6\","
+          + "URI=\"something.m3u8\"\n"
+          + "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audio\",CHANNELS=\"2/6\",NAME=\"Eng26\","
+          + "URI=\"something2.m3u8\"\n"
+          + "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audio\",NAME=\"Eng\","
+          + "URI=\"something3.m3u8\"\n"
+          + "#EXT-X-STREAM-INF:BANDWIDTH=1280000,"
+          + "CODECS=\"mp4a.40.2,avc1.66.30\",AUDIO=\"audio\",RESOLUTION=304x128\n"
+          + "http://example.com/low.m3u8\n";
+
   private static final String PLAYLIST_WITHOUT_CC =
       " #EXTM3U \n"
           + "#EXT-X-MEDIA:TYPE=CLOSED-CAPTIONS,"
@@ -216,6 +228,17 @@ public class HlsMasterPlaylistParserTest {
     assertThat(closedCaptionFormat.language).isEqualTo("es");
   }
 
+  @Test
+  public void testPlaylistWithChannelsAttribute() throws IOException {
+    HlsMasterPlaylist playlist =
+        parseMasterPlaylist(PLAYLIST_URI, PLAYLIST_WITH_CHANNELS_ATTRIBUTE);
+    List<HlsMasterPlaylist.HlsUrl> audios = playlist.audios;
+    assertThat(audios).hasSize(3);
+    assertThat(audios.get(0).format.channelCount).isEqualTo(6);
+    assertThat(audios.get(1).format.channelCount).isEqualTo(2);
+    assertThat(audios.get(2).format.channelCount).isEqualTo(Format.NO_VALUE);
+  }
+
   @Test
   public void testPlaylistWithoutClosedCaptions() throws IOException {
     HlsMasterPlaylist playlist = parseMasterPlaylist(PLAYLIST_URI, PLAYLIST_WITHOUT_CC);