Use peak rather than average bitrate for HLS

This is a minor change ahead of merging a full variant of
https://github.com/google/ExoPlayer/pull/6706, to make
re-buffers less likely.

Also remove variable substitution when parsing
AVERAGE-BANDWIDTH (it's not required for integer attributes)

PiperOrigin-RevId: 283554106

RELEASENOTES.md

@@ -126,9 +126,11 @@
     fragment) ([#6470](https://github.com/google/ExoPlayer/issues/6470)).
 * DASH: Support negative @r values in segment timelines
   ([#1787](https://github.com/google/ExoPlayer/issues/1787)).
-* HLS: Fix issue where streams could get stuck in an infinite buffering state
+* HLS:
-  after a postroll ad
+  * Use peak bitrate rather than average bitrate for adaptive track selection.
-  ([#6314](https://github.com/google/ExoPlayer/issues/6314)).
+  * Fix issue where streams could get stuck in an infinite buffering state
+    after a postroll ad
+    ([#6314](https://github.com/google/ExoPlayer/issues/6314)).
 * AV1 extension:
   * New in this release. The AV1 extension allows use of the
     [libgav1 software decoder](https://chromium.googlesource.com/codecs/libgav1/)

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

@@ -304,12 +304,8 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
       } else if (line.startsWith(TAG_STREAM_INF)) {
         noClosedCaptions |= line.contains(ATTR_CLOSED_CAPTIONS_NONE);
         int bitrate = parseIntAttr(line, REGEX_BANDWIDTH);
-        String averageBandwidthString =
+        // TODO: Plumb this into Format.
-            parseOptionalStringAttr(line, REGEX_AVERAGE_BANDWIDTH, variableDefinitions);
+        int averageBitrate = parseOptionalIntAttr(line, REGEX_AVERAGE_BANDWIDTH, -1);
-        if (averageBandwidthString != null) {
-          // If available, the average bandwidth attribute is used as the variant's bitrate.
-          bitrate = Integer.parseInt(averageBandwidthString);
-        }
         String codecs = parseOptionalStringAttr(line, REGEX_CODECS, variableDefinitions);
         String resolutionString =
             parseOptionalStringAttr(line, REGEX_RESOLUTION, variableDefinitions);
@@ -869,6 +865,14 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     return Integer.parseInt(parseStringAttr(line, pattern, Collections.emptyMap()));
   }
 
+  private static int parseOptionalIntAttr(String line, Pattern pattern, int defaultValue) {
+    Matcher matcher = pattern.matcher(line);
+    if (matcher.find()) {
+      return Integer.parseInt(matcher.group(1));
+    }
+    return defaultValue;
+  }
+
   private static long parseLongAttr(String line, Pattern pattern) throws ParserException {
     return Long.parseLong(parseStringAttr(line, pattern, Collections.emptyMap()));
   }

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

@@ -243,7 +243,7 @@ public class HlsMasterPlaylistParserTest {
     List<HlsMasterPlaylist.Variant> variants = masterPlaylist.variants;
 
     assertThat(variants.get(0).format.bitrate).isEqualTo(1280000);
-    assertThat(variants.get(1).format.bitrate).isEqualTo(1270000);
+    assertThat(variants.get(1).format.bitrate).isEqualTo(1280000);
   }
 
   @Test