Add container format sniffing in HLS

Issue:#2025

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=211977802

RELEASENOTES.md

@@ -32,6 +32,8 @@
     [VR180](https://github.com/google/spatial-media/blob/master/docs/vr180.md).
 * HLS:
   * Support PlayReady.
+  * Add container format sniffing
+    ([#2025](https://github.com/google/ExoPlayer/issues/2025)).
   * Support alternative `EXT-X-KEY` tags.
   * Support `EXT-X-INDEPENDENT-SEGMENTS` in the master playlist.
   * Support variable substitution

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

@@ -20,7 +20,10 @@ import android.util.Pair;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.extractor.Extractor;
+import com.google.android.exoplayer2.extractor.ExtractorInput;
+import com.google.android.exoplayer2.extractor.PositionHolder;
 import com.google.android.exoplayer2.util.TimestampAdjuster;
+import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 
@@ -45,9 +48,14 @@ public interface HlsExtractorFactory {
    * @param timestampAdjuster Adjuster corresponding to the provided discontinuity sequence number.
    * @param responseHeaders The HTTP response headers associated with the media segment or
    *     initialization section to extract.
+   * @param sniffingExtractorInput The first extractor input that will be passed to the returned
+   *     extractor's {@link Extractor#read(ExtractorInput, PositionHolder)}. Must only be used to
+   *     call {@link Extractor#sniff(ExtractorInput)}.
    * @return A pair containing the {@link Extractor} and a boolean that indicates whether it is a
    *     packed audio extractor. The first element may be {@code previousExtractor} if the factory
    *     has determined it can be re-used.
+   * @throws InterruptedException If the thread is interrupted while sniffing.
+   * @throws IOException If an I/O error is encountered while sniffing.
    */
   Pair<Extractor, Boolean> createExtractor(
       Extractor previousExtractor,
@@ -56,5 +64,7 @@ public interface HlsExtractorFactory {
       List<Format> muxedCaptionFormats,
       DrmInitData drmInitData,
       TimestampAdjuster timestampAdjuster,
-      Map<String, List<String>> responseHeaders);
+      Map<String, List<String>> responseHeaders,
+      ExtractorInput sniffingExtractorInput)
+      throws InterruptedException, IOException;
 }

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

@@ -73,15 +73,13 @@ import java.util.concurrent.atomic.AtomicInteger;
   private final List<Format> muxedCaptionFormats;
   private final DrmInitData drmInitData;
   private final Extractor previousExtractor;
+  private final Id3Decoder id3Decoder;
+  private final ParsableByteArray id3Data;
 
   private Extractor extractor;
-  private boolean isPackedAudioExtractor;
-  private Id3Decoder id3Decoder;
-  private ParsableByteArray id3Data;
   private HlsSampleStreamWrapper output;
   private int initSegmentBytesLoaded;
   private int nextLoadPosition;
-  private boolean id3TimestampPeeked;
   private boolean initLoadCompleted;
   private volatile boolean loadCanceled;
   private boolean loadCompleted;
@@ -158,6 +156,8 @@ import java.util.concurrent.atomic.AtomicInteger;
       previousExtractor = previousChunk.discontinuitySequenceNumber != discontinuitySequenceNumber
           || shouldSpliceIn ? null : previousChunk.extractor;
     } else {
+      id3Decoder = new Id3Decoder();
+      id3Data = new ParsableByteArray(Id3Decoder.ID3_HEADER_LENGTH);
       shouldSpliceIn = false;
     }
     this.previousExtractor = previousExtractor;
@@ -244,12 +244,6 @@ import java.util.concurrent.atomic.AtomicInteger;
     }
     try {
       ExtractorInput input = prepareExtraction(dataSource, loadDataSpec);
-      if (isPackedAudioExtractor && !id3TimestampPeeked) {
-        long id3Timestamp = peekId3PrivTimestamp(input);
-        id3TimestampPeeked = true;
-        output.setSampleOffsetUs(id3Timestamp != C.TIME_UNSET
-            ? timestampAdjuster.adjustTsTimestamp(id3Timestamp) : startTimeUs);
-      }
       if (skipLoadedBytes) {
         input.skipFully(nextLoadPosition);
       }
@@ -267,10 +261,16 @@ import java.util.concurrent.atomic.AtomicInteger;
   }
 
   private DefaultExtractorInput prepareExtraction(DataSource dataSource, DataSpec dataSpec)
-      throws IOException {
+      throws IOException, InterruptedException {
     long bytesToRead = dataSource.open(dataSpec);
 
+    DefaultExtractorInput extractorInput =
+        new DefaultExtractorInput(dataSource, dataSpec.absoluteStreamPosition, bytesToRead);
+
     if (extractor == null) {
+      long id3Timestamp = peekId3PrivTimestamp(extractorInput);
+      extractorInput.resetPeekPosition();
+
       Pair<Extractor, Boolean> extractorData =
           extractorFactory.createExtractor(
               previousExtractor,
@@ -279,22 +279,26 @@ import java.util.concurrent.atomic.AtomicInteger;
               muxedCaptionFormats,
               drmInitData,
               timestampAdjuster,
-              dataSource.getResponseHeaders());
+              dataSource.getResponseHeaders(),
+              extractorInput);
       extractor = extractorData.first;
-      isPackedAudioExtractor = extractorData.second;
       boolean reusingExtractor = extractor == previousExtractor;
-      initLoadCompleted = reusingExtractor && initDataSpec != null;
-      if (isPackedAudioExtractor && id3Data == null) {
-        id3Decoder = new Id3Decoder();
-        id3Data = new ParsableByteArray(Id3Decoder.ID3_HEADER_LENGTH);
+      boolean isPackedAudioExtractor = extractorData.second;
+      if (isPackedAudioExtractor) {
+        output.setSampleOffsetUs(
+            id3Timestamp != C.TIME_UNSET
+                ? timestampAdjuster.adjustTsTimestamp(id3Timestamp)
+                : startTimeUs);
       }
+      initLoadCompleted = reusingExtractor && initDataSpec != null;
+
       output.init(uid, shouldSpliceIn, reusingExtractor);
       if (!reusingExtractor) {
         extractor.init(output);
       }
     }
 
-    return new DefaultExtractorInput(dataSource, dataSpec.absoluteStreamPosition, bytesToRead);
+    return extractorInput;
   }
 
   /**
@@ -309,7 +313,8 @@ import java.util.concurrent.atomic.AtomicInteger;
    */
   private long peekId3PrivTimestamp(ExtractorInput input) throws IOException, InterruptedException {
     input.resetPeekPosition();
-    if (!input.peekFully(id3Data.data, 0, Id3Decoder.ID3_HEADER_LENGTH, true)) {
+    if (input.getLength() < Id3Decoder.ID3_HEADER_LENGTH
+        || !input.peekFully(id3Data.data, 0, Id3Decoder.ID3_HEADER_LENGTH, true)) {
       return C.TIME_UNSET;
     }
     id3Data.reset(Id3Decoder.ID3_HEADER_LENGTH);