Revert logic to decide whether meta atom is full

The previous logic was changed under the assumption that the first box
inside a meta box was not always an hdlr box, but this is not true.

#minor-release

PiperOrigin-RevId: 357200713

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -231,20 +231,22 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
    * <p>Atoms of type {@link Atom#TYPE_meta} are defined to be full atoms which have four additional
    * bytes for a version and a flags field (see 4.2 'Object Structure' in ISO/IEC 14496-12:2005).
    * QuickTime do not have such a full box structure. Since some of these files are encoded wrongly,
-   * we can't rely on the file type though. Instead we must check the 4 bytes after the common
+   * we can't rely on the file type though. Instead we must check the 8 bytes after the common
    * header bytes ourselves.
    *
-   * @param meta The 4 or more bytes following the meta atom size and type.
+   * @param meta The 8 or more bytes following the meta atom size and type.
    */
   public static void maybeSkipRemainingMetaAtomHeaderBytes(ParsableByteArray meta) {
-    int startPosition = meta.getPosition();
-    // The next 4 bytes can be either:
-    // (iso) 4 zero bytes (version + flags)
-    // (qt)  4 byte size of next atom
+    int endPosition = meta.getPosition();
+    // The next 8 bytes can be either:
+    // (iso) [1 byte version + 3 bytes flags][4 byte size of next atom]
+    // (qt)  [4 byte size of next atom      ][4 byte hdlr atom type   ]
     // In case of (iso) we need to skip the next 4 bytes.
-    if (meta.readInt() != 0) {
-      meta.setPosition(startPosition);
+    meta.skipBytes(4);
+    if (meta.readInt() != Atom.TYPE_hdlr) {
+      endPosition += 4;
     }
+    meta.setPosition(endPosition);
   }
 
   /**

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java

@@ -728,8 +728,8 @@ public final class Mp4Extractor implements Extractor, SeekMap {
   }
 
   private void maybeSkipRemainingMetaAtomHeaderBytes(ExtractorInput input) throws IOException {
-    scratch.reset(4);
-    input.peekFully(scratch.getData(), 0, 4);
+    scratch.reset(8);
+    input.peekFully(scratch.getData(), 0, 8);
     AtomParsers.maybeSkipRemainingMetaAtomHeaderBytes(scratch);
     input.skipFully(scratch.getPosition());
     input.resetPeekPosition();