WavExtractor: split read stages into states

This refactoring is the basis to support RF64 (see
Issue: google/ExoPlayer#9543).

#minor-release

PiperOrigin-RevId: 406377924

libraries/extractor/src/main/java/androidx/media3/extractor/wav/WavExtractor.java

@@ -19,6 +19,7 @@ import static java.lang.Math.max;
 import static java.lang.Math.min;
 
 import android.util.Pair;
+import androidx.annotation.IntDef;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
@@ -35,8 +36,14 @@ import androidx.media3.extractor.PositionHolder;
 import androidx.media3.extractor.TrackOutput;
 import androidx.media3.extractor.WavUtil;
 import java.io.IOException;
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
 /** Extracts data from WAV byte streams. */
 @UnstableApi
@@ -52,13 +59,26 @@ public final class WavExtractor implements Extractor {
   /** Factory for {@link WavExtractor} instances. */
   public static final ExtractorsFactory FACTORY = () -> new Extractor[] {new WavExtractor()};
 
+  /** Parser state. */
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @Target({ElementType.TYPE_USE})
+  @IntDef({STATE_READING_HEADER, STATE_SKIPPING_TO_SAMPLE_DATA, STATE_READING_SAMPLE_DATA})
+  private @interface State {}
+
+  private static final int STATE_READING_HEADER = 0;
+  private static final int STATE_SKIPPING_TO_SAMPLE_DATA = 1;
+  private static final int STATE_READING_SAMPLE_DATA = 2;
+
   private @MonotonicNonNull ExtractorOutput extractorOutput;
   private @MonotonicNonNull TrackOutput trackOutput;
+  private @State int state;
   private @MonotonicNonNull OutputWriter outputWriter;
   private int dataStartPosition;
   private long dataEndPosition;
 
   public WavExtractor() {
+    state = STATE_READING_HEADER;
     dataStartPosition = C.POSITION_UNSET;
     dataEndPosition = C.POSITION_UNSET;
   }
@@ -77,6 +97,7 @@ public final class WavExtractor implements Extractor {
 
   @Override
   public void seek(long position, long timeUs) {
+    state = position == 0 ? STATE_READING_HEADER : STATE_READING_SAMPLE_DATA;
     if (outputWriter != null) {
       outputWriter.reset(timeUs);
     }
@@ -88,15 +109,44 @@ public final class WavExtractor implements Extractor {
   }
 
   @Override
+  @ReadResult
   public int read(ExtractorInput input, PositionHolder seekPosition) throws IOException {
     assertInitialized();
-    if (outputWriter == null) {
+    switch (state) {
+      case STATE_READING_HEADER:
+        readHeader(input);
+        return Extractor.RESULT_CONTINUE;
+      case STATE_SKIPPING_TO_SAMPLE_DATA:
+        skipToSampleData(input);
+        return Extractor.RESULT_CONTINUE;
+      case STATE_READING_SAMPLE_DATA:
+        return readSampleData(input);
+      default:
+        throw new IllegalStateException();
+    }
+  }
+
+  @EnsuresNonNull({"extractorOutput", "trackOutput"})
+  private void assertInitialized() {
+    Assertions.checkStateNotNull(trackOutput);
+    Util.castNonNull(extractorOutput);
+  }
+
+  @RequiresNonNull({"extractorOutput", "trackOutput"})
+  private void readHeader(ExtractorInput input) throws IOException {
+    Assertions.checkState(input.getPosition() == 0);
+    if (dataStartPosition != C.POSITION_UNSET) {
+      input.skipFully(dataStartPosition);
+      state = STATE_READING_SAMPLE_DATA;
+      return;
+    }
     WavHeader header = WavHeaderReader.peek(input);
     if (header == null) {
       // Should only happen if the media wasn't sniffed.
       throw ParserException.createForMalformedContainer(
           "Unsupported or unrecognized wav header.", /* cause= */ null);
     }
+    input.skipFully((int) (input.getPeekPosition() - input.getPosition()));
 
     if (header.formatType == WavUtil.TYPE_IMA_ADPCM) {
       outputWriter = new ImaAdPcmOutputWriter(extractorOutput, trackOutput, header);
@@ -127,26 +177,24 @@ public final class WavExtractor implements Extractor {
           new PassthroughOutputWriter(
               extractorOutput, trackOutput, header, MimeTypes.AUDIO_RAW, pcmEncoding);
     }
+    state = STATE_SKIPPING_TO_SAMPLE_DATA;
   }
 
-    if (dataStartPosition == C.POSITION_UNSET) {
+  private void skipToSampleData(ExtractorInput input) throws IOException {
-      Pair<Long, Long> dataBounds = WavHeaderReader.skipToData(input);
+    Pair<Long, Long> dataBounds = WavHeaderReader.skipToSampleData(input);
     dataStartPosition = dataBounds.first.intValue();
     dataEndPosition = dataBounds.second;
-      outputWriter.init(dataStartPosition, dataEndPosition);
+    Assertions.checkNotNull(outputWriter).init(dataStartPosition, dataEndPosition);
-    } else if (input.getPosition() == 0) {
+    state = STATE_READING_SAMPLE_DATA;
-      input.skipFully(dataStartPosition);
   }
 
+  @ReadResult
+  private int readSampleData(ExtractorInput input) throws IOException {
     Assertions.checkState(dataEndPosition != C.POSITION_UNSET);
     long bytesLeft = dataEndPosition - input.getPosition();
-    return outputWriter.sampleData(input, bytesLeft) ? RESULT_END_OF_INPUT : RESULT_CONTINUE;
+    return Assertions.checkNotNull(outputWriter).sampleData(input, bytesLeft)
-  }
+        ? RESULT_END_OF_INPUT
-
+        : RESULT_CONTINUE;
-  @EnsuresNonNull({"extractorOutput", "trackOutput"})
-  private void assertInitialized() {
-    Assertions.checkStateNotNull(trackOutput);
-    Util.castNonNull(extractorOutput);
   }
 
   /** Writes to the extractor's output. */

libraries/extractor/src/main/java/androidx/media3/extractor/wav/WavHeaderReader.java

@@ -108,7 +108,7 @@ import java.io.IOException;
    * @throws ParserException If an error occurs parsing chunks.
    * @throws IOException If reading from the input fails.
    */
-  public static Pair<Long, Long> skipToData(ExtractorInput input) throws IOException {
+  public static Pair<Long, Long> skipToSampleData(ExtractorInput input) throws IOException {
     Assertions.checkNotNull(input);
 
     // Make sure the peek position is set to the read position before we peek the first header.
@@ -118,14 +118,8 @@ import java.io.IOException;
     // Skip all chunks until we find the data header.
     ChunkHeader chunkHeader = ChunkHeader.peek(input, scratch);
     while (chunkHeader.id != WavUtil.DATA_FOURCC) {
-      if (chunkHeader.id != WavUtil.RIFF_FOURCC && chunkHeader.id != WavUtil.FMT_FOURCC) {
       Log.w(TAG, "Ignoring unknown WAV chunk: " + chunkHeader.id);
-      }
       long bytesToSkip = ChunkHeader.SIZE_IN_BYTES + chunkHeader.size;
-      // Override size of RIFF chunk, since it describes its size as the entire file.
-      if (chunkHeader.id == WavUtil.RIFF_FOURCC) {
-        bytesToSkip = ChunkHeader.SIZE_IN_BYTES + 4;
-      }
       if (bytesToSkip > Integer.MAX_VALUE) {
         throw ParserException.createForUnsupportedContainerFeature(
             "Chunk is too large (~2GB+) to skip; id: " + chunkHeader.id);