Skip AnnexB to Avcc conversion for AV1 video format

The AV1 video stream does not contain NAL unit which is a concept
specific to H.264/H.265.
This was not caught before muxer does an in place replacement of
`NAL start code` with `NAL length`. In the absence of `NAL start code`
it was automatically a no-op.

PiperOrigin-RevId: 617193317

library/muxer/src/main/java/com/google/android/exoplayer2/muxer/AnnexBUtils.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.muxer;
 
+import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.common.collect.ImmutableList;
 import java.nio.ByteBuffer;
 
@@ -95,6 +96,15 @@ public static ByteBuffer stripEmulationPrevention(ByteBuffer input) {
     return output;
   }
 
+  /**
+   * Returns whether the sample of the given MIME type will contain NAL units in Annex-B format
+   * (ISO/IEC 14496-10 Annex B, which uses start codes to delineate NAL units).
+   */
+  public static boolean doesSampleContainAnnexBNalUnits(String sampleMimeType) {
+    return sampleMimeType.equals(MimeTypes.VIDEO_H264)
+        || sampleMimeType.equals(MimeTypes.VIDEO_H265);
+  }
+
   private static ByteBuffer getBytes(ByteBuffer buf, int offset, int length) {
     ByteBuffer result = buf.duplicate();
     result.position(offset);

library/muxer/src/main/java/com/google/android/exoplayer2/muxer/BasicMp4Writer.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.muxer;
 
+import static com.google.android.exoplayer2.muxer.AnnexBUtils.doesSampleContainAnnexBNalUnits;
 import static com.google.android.exoplayer2.util.Assertions.checkArgument;
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
 import static com.google.android.exoplayer2.util.Assertions.checkState;
@@ -24,7 +25,6 @@
 import android.media.MediaCodec.BufferInfo;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.muxer.Mp4Muxer.TrackToken;
-import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
 import com.google.common.collect.Range;
 import java.io.FileOutputStream;
@@ -303,7 +303,7 @@ private void flushPending(Track track) throws IOException {
 
       // Convert the H.264/H.265 samples from Annex-B format (output by MediaCodec) to
       // Avcc format (required by MP4 container).
-      if (MimeTypes.isVideo(track.format.sampleMimeType)) {
+      if (doesSampleContainAnnexBNalUnits(checkNotNull(track.format.sampleMimeType))) {
         annexBToAvccConverter.process(currentSampleByteBuffer);
       }
 

library/muxer/src/main/java/com/google/android/exoplayer2/muxer/FragmentedMp4Writer.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.muxer;
 
+import static com.google.android.exoplayer2.muxer.AnnexBUtils.doesSampleContainAnnexBNalUnits;
 import static com.google.android.exoplayer2.muxer.Boxes.BOX_HEADER_SIZE;
 import static com.google.android.exoplayer2.muxer.Boxes.MFHD_BOX_CONTENT_SIZE;
 import static com.google.android.exoplayer2.muxer.Boxes.TFHD_BOX_CONTENT_SIZE;
@@ -253,7 +254,7 @@ private void writeMdatBox() throws IOException {
 
         // Convert the H.264/H.265 samples from Annex-B format (output by MediaCodec) to
         // Avcc format (required by MP4 container).
-        if (MimeTypes.isVideo(currentTrack.format.sampleMimeType)) {
+        if (doesSampleContainAnnexBNalUnits(checkNotNull(currentTrack.format.sampleMimeType))) {
           annexBToAvccConverter.process(currentSampleByteBuffer);
         }
         bytesWritten += output.write(currentSampleByteBuffer);