Some extractor fixes

- Fix Ogg extractor to work without sniffing.
- Fix extractors to handle seek() before init().
- Add tests for both issues.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=163992343

extensions/flac/src/androidTest/java/com/google/android/exoplayer2/ext/flac/FlacExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public class FlacExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new FlacExtractor();

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacExtractor.java

@@ -159,13 +159,17 @@ public final class FlacExtractor implements Extractor {
     if (position == 0) {
       metadataParsed = false;
     }
-    decoderJni.reset(position);
+    if (decoderJni != null) {
+      decoderJni.reset(position);
+    }
   }
 
   @Override
   public void release() {
-    decoderJni.release();
+    if (decoderJni != null) {
-    decoderJni = null;
+      decoderJni.release();
+      decoderJni = null;
+    }
   }
 
 }

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/flv/FlvExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class FlvExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new FlvExtractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class MatroskaExtractorTest extends InstrumentationTestCase {
 
   public void testMkvSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new MatroskaExtractor();
@@ -35,7 +35,7 @@ public final class MatroskaExtractorTest extends InstrumentationTestCase {
   }
 
   public void testWebmSubsampleEncryption() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new MatroskaExtractor();
@@ -44,7 +44,7 @@ public final class MatroskaExtractorTest extends InstrumentationTestCase {
   }
 
   public void testWebmSubsampleEncryptionWithAltrefFrames() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new MatroskaExtractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/mp3/Mp3ExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class Mp3ExtractorTest extends InstrumentationTestCase {
 
   public void testMp3Sample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new Mp3Extractor();
@@ -35,7 +35,7 @@ public final class Mp3ExtractorTest extends InstrumentationTestCase {
   }
 
   public void testTrimmedMp3Sample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new Mp3Extractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4ExtractorTest.java

@@ -27,13 +27,13 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class FragmentedMp4ExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts
+    ExtractorAsserts.assertBehavior(getExtractorFactory(), "mp4/sample_fragmented.mp4",
-        .assertOutput(getExtractorFactory(), "mp4/sample_fragmented.mp4", getInstrumentation());
+        getInstrumentation());
   }
 
   public void testSampleWithSeiPayloadParsing() throws Exception {
     // Enabling the CEA-608 track enables SEI payload parsing.
-    ExtractorAsserts.assertOutput(
+    ExtractorAsserts.assertBehavior(
         getExtractorFactory(FragmentedMp4Extractor.FLAG_ENABLE_CEA608_TRACK),
         "mp4/sample_fragmented_sei.mp4", getInstrumentation());
   }

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/mp4/Mp4ExtractorTest.java

@@ -28,7 +28,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class Mp4ExtractorTest extends InstrumentationTestCase {
 
   public void testMp4Sample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new Mp4Extractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ogg/OggExtractorTest.java

@@ -36,20 +36,21 @@ public final class OggExtractorTest extends InstrumentationTestCase {
   };
 
   public void testOpus() throws Exception {
-    ExtractorAsserts.assertOutput(OGG_EXTRACTOR_FACTORY, "ogg/bear.opus", getInstrumentation());
+    ExtractorAsserts.assertBehavior(OGG_EXTRACTOR_FACTORY, "ogg/bear.opus", getInstrumentation());
   }
 
   public void testFlac() throws Exception {
-    ExtractorAsserts.assertOutput(OGG_EXTRACTOR_FACTORY, "ogg/bear_flac.ogg", getInstrumentation());
+    ExtractorAsserts.assertBehavior(OGG_EXTRACTOR_FACTORY, "ogg/bear_flac.ogg",
+        getInstrumentation());
   }
 
   public void testFlacNoSeektable() throws Exception {
-    ExtractorAsserts.assertOutput(OGG_EXTRACTOR_FACTORY, "ogg/bear_flac_noseektable.ogg",
+    ExtractorAsserts.assertBehavior(OGG_EXTRACTOR_FACTORY, "ogg/bear_flac_noseektable.ogg",
         getInstrumentation());
   }
 
   public void testVorbis() throws Exception {
-    ExtractorAsserts.assertOutput(OGG_EXTRACTOR_FACTORY, "ogg/bear_vorbis.ogg",
+    ExtractorAsserts.assertBehavior(OGG_EXTRACTOR_FACTORY, "ogg/bear_vorbis.ogg",
         getInstrumentation());
   }
 

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/rawcc/RawCcExtractorTest.java

@@ -30,7 +30,7 @@ import com.google.android.exoplayer2.util.MimeTypes;
 public final class RawCcExtractorTest extends InstrumentationTestCase {
 
   public void testRawCcSample() throws Exception {
-    ExtractorAsserts.assertOutput(
+    ExtractorAsserts.assertBehavior(
         new ExtractorFactory() {
           @Override
           public Extractor create() {

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ts/Ac3ExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class Ac3ExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new Ac3Extractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class AdtsExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new AdtsExtractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ts/PsExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class PsExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new PsExtractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ts/TsExtractorTest.java

@@ -45,7 +45,7 @@ public final class TsExtractorTest extends InstrumentationTestCase {
   private static final int TS_SYNC_BYTE = 0x47; // First byte of each TS packet.
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new TsExtractor();

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/wav/WavExtractorTest.java

@@ -26,7 +26,7 @@ import com.google.android.exoplayer2.testutil.ExtractorAsserts.ExtractorFactory;
 public final class WavExtractorTest extends InstrumentationTestCase {
 
   public void testSample() throws Exception {
-    ExtractorAsserts.assertOutput(new ExtractorFactory() {
+    ExtractorAsserts.assertBehavior(new ExtractorFactory() {
       @Override
       public Extractor create() {
         return new WavExtractor();

library/core/src/main/java/com/google/android/exoplayer2/extractor/Extractor.java

@@ -63,7 +63,8 @@ public interface Extractor {
   void init(ExtractorOutput output);
 
   /**
-   * Extracts data read from a provided {@link ExtractorInput}.
+   * Extracts data read from a provided {@link ExtractorInput}. Must not be called before
+   * {@link #init(ExtractorOutput)}.
    * <p>
    * A single call to this method will block until some progress has been made, but will not block
    * for longer than this. Hence each call will consume only a small amount of input data.

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

@@ -45,30 +45,14 @@ public class OggExtractor implements Extractor {
 
   private static final int MAX_VERIFICATION_BYTES = 8;
 
+  private ExtractorOutput output;
   private StreamReader streamReader;
+  private boolean streamReaderInitialized;
 
   @Override
   public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
     try {
-      OggPageHeader header = new OggPageHeader();
+      return sniffInternal(input);
-      if (!header.populate(input, true) || (header.type & 0x02) != 0x02) {
-        return false;
-      }
-
-      int length = Math.min(header.bodySize, MAX_VERIFICATION_BYTES);
-      ParsableByteArray scratch = new ParsableByteArray(length);
-      input.peekFully(scratch.data, 0, length);
-
-      if (FlacReader.verifyBitstreamType(resetPosition(scratch))) {
-        streamReader = new FlacReader();
-      } else if (VorbisReader.verifyBitstreamType(resetPosition(scratch))) {
-        streamReader = new VorbisReader();
-      } else if (OpusReader.verifyBitstreamType(resetPosition(scratch))) {
-        streamReader = new OpusReader();
-      } else {
-        return false;
-      }
-      return true;
     } catch (ParserException e) {
       return false;
     }
@@ -76,15 +60,14 @@ public class OggExtractor implements Extractor {
 
   @Override
   public void init(ExtractorOutput output) {
-    TrackOutput trackOutput = output.track(0, C.TRACK_TYPE_AUDIO);
+    this.output = output;
-    output.endTracks();
-    // TODO: fix the case if sniff() isn't called
-    streamReader.init(output, trackOutput);
   }
 
   @Override
   public void seek(long position, long timeUs) {
-    streamReader.seek(position, timeUs);
+    if (streamReader != null) {
+      streamReader.seek(position, timeUs);
+    }
   }
 
   @Override
@@ -95,12 +78,41 @@ public class OggExtractor implements Extractor {
   @Override
   public int read(ExtractorInput input, PositionHolder seekPosition)
       throws IOException, InterruptedException {
+    if (streamReader == null) {
+      if (!sniffInternal(input)) {
+        throw new ParserException("Failed to determine bitstream type");
+      }
+      input.resetPeekPosition();
+    }
+    if (!streamReaderInitialized) {
+      TrackOutput trackOutput = output.track(0, C.TRACK_TYPE_AUDIO);
+      output.endTracks();
+      streamReader.init(output, trackOutput);
+      streamReaderInitialized = true;
+    }
     return streamReader.read(input, seekPosition);
   }
 
-  //@VisibleForTesting
+  private boolean sniffInternal(ExtractorInput input) throws IOException, InterruptedException {
-  /* package */ StreamReader getStreamReader() {
+    OggPageHeader header = new OggPageHeader();
-    return streamReader;
+    if (!header.populate(input, true) || (header.type & 0x02) != 0x02) {
+      return false;
+    }
+
+    int length = Math.min(header.bodySize, MAX_VERIFICATION_BYTES);
+    ParsableByteArray scratch = new ParsableByteArray(length);
+    input.peekFully(scratch.data, 0, length);
+
+    if (FlacReader.verifyBitstreamType(resetPosition(scratch))) {
+      streamReader = new FlacReader();
+    } else if (VorbisReader.verifyBitstreamType(resetPosition(scratch))) {
+      streamReader = new VorbisReader();
+    } else if (OpusReader.verifyBitstreamType(resetPosition(scratch))) {
+      streamReader = new OpusReader();
+    } else {
+      return false;
+    }
+    return true;
   }
 
   private static ParsableByteArray resetPosition(ParsableByteArray scratch) {

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

@@ -41,7 +41,8 @@ import java.io.IOException;
     OggSeeker oggSeeker;
   }
 
-  private OggPacket oggPacket;
+  private final OggPacket oggPacket;
+
   private TrackOutput trackOutput;
   private ExtractorOutput extractorOutput;
   private OggSeeker oggSeeker;
@@ -55,11 +56,13 @@ import java.io.IOException;
   private boolean seekMapSet;
   private boolean formatSet;
 
+  public StreamReader() {
+    oggPacket = new OggPacket();
+  }
+
   void init(ExtractorOutput output, TrackOutput trackOutput) {
     this.extractorOutput = output;
     this.trackOutput = trackOutput;
-    this.oggPacket = new OggPacket();
-
     reset(true);
   }
 

library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac3Extractor.java

@@ -56,9 +56,9 @@ public final class Ac3Extractor implements Extractor {
   private static final int ID3_TAG = Util.getIntegerCodeForString("ID3");
 
   private final long firstSampleTimestampUs;
+  private final Ac3Reader reader;
   private final ParsableByteArray sampleData;
 
-  private Ac3Reader reader;
   private boolean startedPacket;
 
   public Ac3Extractor() {
@@ -67,6 +67,7 @@ public final class Ac3Extractor implements Extractor {
 
   public Ac3Extractor(long firstSampleTimestampUs) {
     this.firstSampleTimestampUs = firstSampleTimestampUs;
+    reader = new Ac3Reader();
     sampleData = new ParsableByteArray(MAX_SYNC_FRAME_SIZE);
   }
 
@@ -117,7 +118,6 @@ public final class Ac3Extractor implements Extractor {
 
   @Override
   public void init(ExtractorOutput output) {
-    reader = new Ac3Reader(); // TODO: Add support for embedded ID3.
     reader.createTracks(output, new TrackIdGenerator(0, 1));
     output.endTracks();
     output.seekMap(new SeekMap.Unseekable(C.TIME_UNSET));

library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractor.java

@@ -55,10 +55,9 @@ public final class AdtsExtractor implements Extractor {
   private static final int MAX_SNIFF_BYTES = 8 * 1024;
 
   private final long firstSampleTimestampUs;
+  private final AdtsReader reader;
   private final ParsableByteArray packetBuffer;
 
-  // Accessed only by the loading thread.
-  private AdtsReader reader;
   private boolean startedPacket;
 
   public AdtsExtractor() {
@@ -67,6 +66,7 @@ public final class AdtsExtractor implements Extractor {
 
   public AdtsExtractor(long firstSampleTimestampUs) {
     this.firstSampleTimestampUs = firstSampleTimestampUs;
+    reader = new AdtsReader(true);
     packetBuffer = new ParsableByteArray(MAX_PACKET_SIZE);
   }
 
@@ -127,7 +127,6 @@ public final class AdtsExtractor implements Extractor {
 
   @Override
   public void init(ExtractorOutput output) {
-    reader = new AdtsReader(true);
     reader.createTracks(output, new TrackIdGenerator(0, 1));
     output.endTracks();
     output.seekMap(new SeekMap.Unseekable(C.TIME_UNSET));

testutils/src/main/java/com/google/android/exoplayer2/testutil/ExtractorAsserts.java

@@ -18,6 +18,8 @@ package com.google.android.exoplayer2.testutil;
 import android.app.Instrumentation;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.extractor.Extractor;
+import com.google.android.exoplayer2.extractor.ExtractorInput;
+import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.PositionHolder;
 import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.testutil.FakeExtractorInput.SimulatedIOException;
@@ -42,46 +44,57 @@ public final class ExtractorAsserts {
   private static final String UNKNOWN_LENGTH_EXTENSION = ".unklen" + DUMP_EXTENSION;
 
   /**
-   * Calls {@link #assertOutput(Extractor, String, byte[], Instrumentation, boolean, boolean,
+   * Asserts that an extractor behaves correctly given valid input data:
-   * boolean)} with all possible combinations of "simulate" parameters.
+   * <ul>
+   *   <li>Calls {@link Extractor#seek(long, long)} and {@link Extractor#release()} without calling
+   *   {@link Extractor#init(ExtractorOutput)} to check these calls do not fail.</li>
+   *   <li>Calls {@link #assertOutput(Extractor, String, byte[], Instrumentation, boolean, boolean,
+   *   boolean, boolean)} with all possible combinations of "simulate" parameters.</li>
+   * </ul>
    *
    * @param factory An {@link ExtractorFactory} which creates instances of the {@link Extractor}
    *     class which is to be tested.
-   * @param sampleFile The path to the input sample.
+   * @param file The path to the input sample.
    * @param instrumentation To be used to load the sample file.
    * @throws IOException If reading from the input fails.
    * @throws InterruptedException If interrupted while reading from the input.
-   * @see #assertOutput(Extractor, String, byte[], Instrumentation, boolean, boolean, boolean)
    */
-  public static void assertOutput(ExtractorFactory factory, String sampleFile,
+  public static void assertBehavior(ExtractorFactory factory, String file,
       Instrumentation instrumentation) throws IOException, InterruptedException {
-    byte[] fileData = TestUtil.getByteArray(instrumentation, sampleFile);
+    // Check behavior prior to initialization.
-    assertOutput(factory, sampleFile, fileData, instrumentation);
+    Extractor extractor = factory.create();
+    extractor.seek(0, 0);
+    extractor.release();
+    // Assert output.
+    byte[] fileData = TestUtil.getByteArray(instrumentation, file);
+    assertOutput(factory, file, fileData, instrumentation);
   }
 
   /**
    * Calls {@link #assertOutput(Extractor, String, byte[], Instrumentation, boolean, boolean,
-   * boolean)} with all possible combinations of "simulate" parameters.
+   * boolean, boolean)} with all possible combinations of "simulate" parameters with
+   * {@code sniffFirst} set to true, and makes one additional call with the "simulate" and
+   * {@code sniffFirst} parameters all set to false.
    *
    * @param factory An {@link ExtractorFactory} which creates instances of the {@link Extractor}
    *     class which is to be tested.
-   * @param sampleFile The path to the input sample.
+   * @param file The path to the input sample.
-   * @param fileData Content of the input file.
+   * @param data Content of the input file.
    * @param instrumentation To be used to load the sample file.
    * @throws IOException If reading from the input fails.
    * @throws InterruptedException If interrupted while reading from the input.
-   * @see #assertOutput(Extractor, String, byte[], Instrumentation, boolean, boolean, boolean)
    */
-  public static void assertOutput(ExtractorFactory factory, String sampleFile, byte[] fileData,
+  public static void assertOutput(ExtractorFactory factory, String file, byte[] data,
       Instrumentation instrumentation) throws IOException, InterruptedException {
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation, false, false, false);
+    assertOutput(factory.create(), file, data, instrumentation,  true, false, false, false);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation,  true, false, false);
+    assertOutput(factory.create(), file, data, instrumentation,  true, false, false,  true);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation, false,  true, false);
+    assertOutput(factory.create(), file, data, instrumentation,  true, false,  true, false);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation,  true,  true, false);
+    assertOutput(factory.create(), file, data, instrumentation,  true, false,  true,  true);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation, false, false,  true);
+    assertOutput(factory.create(), file, data, instrumentation,  true,  true, false, false);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation,  true, false,  true);
+    assertOutput(factory.create(), file, data, instrumentation,  true,  true, false,  true);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation, false,  true,  true);
+    assertOutput(factory.create(), file, data, instrumentation,  true,  true,  true, false);
-    assertOutput(factory.create(), sampleFile, fileData, instrumentation,  true,  true,  true);
+    assertOutput(factory.create(), file, data, instrumentation,  true,  true,  true,  true);
+    assertOutput(factory.create(), file, data, instrumentation, false, false, false, false);
   }
 
   /**
@@ -91,34 +104,38 @@ public final class ExtractorAsserts {
    * #UNKNOWN_LENGTH_EXTENSION}" exists, it's preferred.
    *
    * @param extractor The {@link Extractor} to be tested.
-   * @param sampleFile The path to the input sample.
+   * @param file The path to the input sample.
-   * @param fileData Content of the input file.
+   * @param data Content of the input file.
    * @param instrumentation To be used to load the sample file.
-   * @param simulateIOErrors If true simulates IOErrors.
+   * @param sniffFirst Whether to sniff the data by calling {@link Extractor#sniff(ExtractorInput)}
-   * @param simulateUnknownLength If true simulates unknown input length.
+   *     prior to consuming it.
-   * @param simulatePartialReads If true simulates partial reads.
+   * @param simulateIOErrors Whether to simulate IO errors.
+   * @param simulateUnknownLength Whether to simulate unknown input length.
+   * @param simulatePartialReads Whether to simulate partial reads.
    * @return The {@link FakeExtractorOutput} used in the test.
    * @throws IOException If reading from the input fails.
    * @throws InterruptedException If interrupted while reading from the input.
    */
-  public static FakeExtractorOutput assertOutput(Extractor extractor, String sampleFile,
+  public static FakeExtractorOutput assertOutput(Extractor extractor, String file, byte[] data,
-      byte[] fileData, Instrumentation instrumentation, boolean simulateIOErrors,
+      Instrumentation instrumentation, boolean sniffFirst, boolean simulateIOErrors,
       boolean simulateUnknownLength, boolean simulatePartialReads) throws IOException,
       InterruptedException {
-    FakeExtractorInput input = new FakeExtractorInput.Builder().setData(fileData)
+    FakeExtractorInput input = new FakeExtractorInput.Builder().setData(data)
         .setSimulateIOErrors(simulateIOErrors)
         .setSimulateUnknownLength(simulateUnknownLength)
         .setSimulatePartialReads(simulatePartialReads).build();
 
-    Assert.assertTrue(TestUtil.sniffTestData(extractor, input));
+    if (sniffFirst) {
-    input.resetPeekPosition();
+      Assert.assertTrue(TestUtil.sniffTestData(extractor, input));
-    FakeExtractorOutput extractorOutput = consumeTestData(extractor, input, 0, true);
+      input.resetPeekPosition();
+    }
 
+    FakeExtractorOutput extractorOutput = consumeTestData(extractor, input, 0, true);
     if (simulateUnknownLength
-        && assetExists(instrumentation, sampleFile + UNKNOWN_LENGTH_EXTENSION)) {
+        && assetExists(instrumentation, file + UNKNOWN_LENGTH_EXTENSION)) {
-      extractorOutput.assertOutput(instrumentation, sampleFile + UNKNOWN_LENGTH_EXTENSION);
+      extractorOutput.assertOutput(instrumentation, file + UNKNOWN_LENGTH_EXTENSION);
     } else {
-      extractorOutput.assertOutput(instrumentation, sampleFile + ".0" + DUMP_EXTENSION);
+      extractorOutput.assertOutput(instrumentation, file + ".0" + DUMP_EXTENSION);
     }
 
     SeekMap seekMap = extractorOutput.seekMap;
@@ -133,7 +150,7 @@ public final class ExtractorAsserts {
         }
 
         consumeTestData(extractor, input, timeUs, extractorOutput, false);
-        extractorOutput.assertOutput(instrumentation, sampleFile + '.' + j + DUMP_EXTENSION);
+        extractorOutput.assertOutput(instrumentation, file + '.' + j + DUMP_EXTENSION);
       }
     }