Permit duplicate Opus headers

This reinstates the permissive behaviour removed by
fe7e5b8

Test file created by opening bear.opus in a hex editor and naively
duplicating the two header packets, starting at (and including) the
first `OggS` in the file and ending just before the third `OggS`.

#minor-release

Issue: #10038
PiperOrigin-RevId: 452015662

Author: icbaker

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/ogg/OpusReader.java

@@ -15,7 +15,6 @@
  */
 package com.google.android.exoplayer2.extractor.ogg;
 
-import static com.google.android.exoplayer2.util.Assertions.checkState;
 import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull;
 
 import androidx.annotation.Nullable;
@@ -39,10 +38,20 @@
     'O', 'p', 'u', 's', 'T', 'a', 'g', 's'
   };
 
+  private boolean firstCommentHeaderSeen;
+
   public static boolean verifyBitstreamType(ParsableByteArray data) {
     return peekPacketStartsWith(data, OPUS_ID_HEADER_SIGNATURE);
   }
 
+  @Override
+  protected void reset(boolean headerData) {
+    super.reset(headerData);
+    if (headerData) {
+      firstCommentHeaderSeen = false;
+    }
+  }
+
   @Override
   protected long preparePayload(ParsableByteArray packet) {
     return convertTimeToGranule(getPacketDurationUs(packet.getData()));
@@ -57,9 +66,15 @@ protected boolean readHeaders(ParsableByteArray packet, long position, SetupData
       int channelCount = OpusUtil.getChannelCount(headerBytes);
       List<byte[]> initializationData = OpusUtil.buildInitializationData(headerBytes);
 
-      // The ID header must come at the start of the file:
-      // https://datatracker.ietf.org/doc/html/rfc7845#section-3
-      checkState(setupData.format == null);
+      if (setupData.format != null) {
+        // setupData.format being non-null indicates we've already seen an ID header. Multiple ID
+        // headers are not permitted by the Opus spec [1], but have been observed in real files [2],
+        // so we just ignore all subsequent ones.
+        // [1] https://datatracker.ietf.org/doc/html/rfc7845#section-3 and
+        //     https://datatracker.ietf.org/doc/html/rfc7845#section-5
+        // [2] https://github.com/google/ExoPlayer/issues/10038
+        return true;
+      }
       setupData.format =
           new Format.Builder()
               .setSampleMimeType(MimeTypes.AUDIO_OPUS)
@@ -72,6 +87,15 @@ protected boolean readHeaders(ParsableByteArray packet, long position, SetupData
       // The comment header must come immediately after the ID header, so the format will already
       // be populated: https://datatracker.ietf.org/doc/html/rfc7845#section-3
       checkStateNotNull(setupData.format);
+      if (firstCommentHeaderSeen) {
+        // Multiple comment headers are not permitted by the Opus spec [1], but have been observed
+        // in real files [2], so we just ignore all subsequent ones.
+        // [1] https://datatracker.ietf.org/doc/html/rfc7845#section-3 and
+        //     https://datatracker.ietf.org/doc/html/rfc7845#section-5
+        // [2] https://github.com/google/ExoPlayer/issues/10038
+        return true;
+      }
+      firstCommentHeaderSeen = true;
       packet.skipBytes(OPUS_COMMENT_HEADER_SIGNATURE.length);
       VorbisUtil.CommentHeader commentHeader =
           VorbisUtil.readVorbisCommentHeader(

library/extractor/src/test/java/com/google/android/exoplayer2/extractor/ogg/OggExtractorParameterizedTest.java

@@ -43,6 +43,13 @@ public void opus() throws Exception {
     ExtractorAsserts.assertBehavior(OggExtractor::new, "media/ogg/bear.opus", simulationConfig);
   }
 
+  // https://github.com/google/ExoPlayer/issues/10038
+  @Test
+  public void opus_duplicateHeader() throws Exception {
+    ExtractorAsserts.assertBehavior(
+        OggExtractor::new, "media/ogg/bear_duplicate_header.opus", simulationConfig);
+  }
+
   @Test
   public void flac() throws Exception {
     ExtractorAsserts.assertBehavior(OggExtractor::new, "media/ogg/bear_flac.ogg", simulationConfig);