Add WavExtractor for extracting samples from WAV files.

This version only supports 16-bit uncompressed PCM. A follow-up CL will
add support for other sample bit depths.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117809475

library/src/main/java/com/google/android/exoplayer/extractor/ExtractorSampleSource.java

@@ -57,9 +57,10 @@ import java.util.List;
  * <li>Ogg Vorbis ({@link com.google.android.exoplayer.extractor.ogg.OggVorbisExtractor}</li>
  * <li>MP3 ({@link com.google.android.exoplayer.extractor.mp3.Mp3Extractor})</li>
  * <li>AAC ({@link com.google.android.exoplayer.extractor.ts.AdtsExtractor})</li>
- * <li>MPEG TS ({@link com.google.android.exoplayer.extractor.ts.TsExtractor}</li>
- * <li>MPEG PS ({@link com.google.android.exoplayer.extractor.ts.PsExtractor}</li>
- * <li>FLV ({@link com.google.android.exoplayer.extractor.flv.FlvExtractor}</li>
+ * <li>MPEG TS ({@link com.google.android.exoplayer.extractor.ts.TsExtractor})</li>
+ * <li>MPEG PS ({@link com.google.android.exoplayer.extractor.ts.PsExtractor})</li>
+ * <li>FLV ({@link com.google.android.exoplayer.extractor.flv.FlvExtractor})</li>
+ * <li>WAV ({@link com.google.android.exoplayer.extractor.wav.WavExtractor})</li>
  * </ul>
  *
  * <p>Seeking in AAC, MPEG TS and FLV streams is not supported.
@@ -183,6 +184,13 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
     } catch (ClassNotFoundException e) {
       // Extractor not found.
     }
+    try {
+      DEFAULT_EXTRACTOR_CLASSES.add(
+          Class.forName("com.google.android.exoplayer.extractor.wav.WavExtractor")
+              .asSubclass(Extractor.class));
+    } catch (ClassNotFoundException e) {
+      // Extractor not found.
+    }
   }
 
   private final ExtractorHolder extractorHolder;

library/src/main/java/com/google/android/exoplayer/extractor/wav/WavExtractor.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer.extractor.wav;
+
+import com.google.android.exoplayer.C;
+import com.google.android.exoplayer.Format;
+import com.google.android.exoplayer.ParserException;
+import com.google.android.exoplayer.extractor.Extractor;
+import com.google.android.exoplayer.extractor.ExtractorInput;
+import com.google.android.exoplayer.extractor.ExtractorOutput;
+import com.google.android.exoplayer.extractor.PositionHolder;
+import com.google.android.exoplayer.extractor.SeekMap;
+import com.google.android.exoplayer.extractor.TrackOutput;
+import com.google.android.exoplayer.util.MimeTypes;
+
+import java.io.IOException;
+
+/** {@link Extractor} to extract samples from a WAV byte stream. */
+public final class WavExtractor implements Extractor, SeekMap {
+
+  /** Arbitrary maximum input size of 32KB, which is ~170ms of 16-bit stereo PCM audio at 48KHz. */
+  private static final int MAX_INPUT_SIZE = 32 * 1024;
+
+  private ExtractorOutput extractorOutput;
+  private TrackOutput trackOutput;
+  private WavHeader wavHeader;
+
+  @Override
+  public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
+    return WavHeaderReader.peek(input) != null;
+  }
+
+  @Override
+  public void init(ExtractorOutput output) {
+    extractorOutput = output;
+    trackOutput = output.track(0);
+    wavHeader = null;
+    output.endTracks();
+  }
+
+  @Override
+  public void seek() {
+    // Do nothing.
+  }
+
+  @Override
+  public int read(ExtractorInput input, PositionHolder seekPosition)
+      throws IOException, InterruptedException {
+    if (wavHeader == null) {
+      wavHeader = WavHeaderReader.peek(input);
+      if (wavHeader == null) {
+        // Should only happen if the media wasn't sniffed.
+        throw new ParserException("Unsupported or unrecognized wav header.");
+      }
+      Format format = Format.createAudioSampleFormat(null, MimeTypes.AUDIO_RAW,
+          wavHeader.getBitrate(), MAX_INPUT_SIZE, wavHeader.getNumChannels(),
+          wavHeader.getSampleRateHz(), null, null);
+      trackOutput.format(format);
+    }
+
+    if (!wavHeader.hasDataBounds()) {
+      WavHeaderReader.skipToData(input, wavHeader);
+      extractorOutput.seekMap(this);
+    }
+
+    long inputPosition = input.getPosition();
+    int bytesRead = trackOutput.sampleData(input, MAX_INPUT_SIZE, true);
+    if (bytesRead == RESULT_END_OF_INPUT) {
+      return RESULT_END_OF_INPUT;
+    }
+
+    trackOutput.sampleMetadata(
+        wavHeader.getTimeUs(inputPosition), C.SAMPLE_FLAG_SYNC, bytesRead, 0, null);
+    return RESULT_CONTINUE;
+  }
+
+  // SeekMap implementation.
+
+  @Override
+  public long getDurationUs() {
+    return wavHeader.getDurationUs();
+  }
+
+  @Override
+  public boolean isSeekable() {
+    return true;
+  }
+
+  @Override
+  public long getPosition(long timeUs) {
+    return wavHeader.getPosition(timeUs);
+  }
+}

library/src/main/java/com/google/android/exoplayer/extractor/wav/WavHeader.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer.extractor.wav;
+
+import com.google.android.exoplayer.C;
+
+/** Header for a WAV file. */
+/*package*/ final class WavHeader {
+
+  /** Number of audio chanels. */
+  private final int numChannels;
+  /** Sample rate in Hertz. */
+  private final int sampleRateHz;
+  /** Average bytes per second for the sample data. */
+  private final int averageBytesPerSecond;
+  /** Alignment for frames of audio data; should equal {@code numChannels * bitsPerSample / 8}. */
+  private final int blockAlignment;
+  /** Bits per sample for the audio data. */
+  private final int bitsPerSample;
+  /** Offset to the start of sample data. */
+  private long dataStartPosition;
+  /** Total size in bytes of the sample data. */
+  private long dataSize;
+
+  public WavHeader(
+      int numChannels,
+      int sampleRateHz,
+      int averageBytesPerSecond,
+      int blockAlignment,
+      int bitsPerSample) {
+    this.numChannels = numChannels;
+    this.sampleRateHz = sampleRateHz;
+    this.averageBytesPerSecond = averageBytesPerSecond;
+    this.blockAlignment = blockAlignment;
+    this.bitsPerSample = bitsPerSample;
+  }
+
+  /** Returns the duration in microseconds of this WAV. */
+  public long getDurationUs() {
+    return (getNumFrames() * C.MICROS_PER_SECOND) / sampleRateHz;
+  }
+
+  /** Returns the number of samples in this WAV. */
+  public long getNumSamples() {
+    return dataSize / getBytesPerSample();
+  }
+
+  /** Returns the number of frames in this WAV. */
+  public long getNumFrames() {
+    return getNumSamples() / getNumChannels();
+  }
+
+  /** Returns the bytes per sample of this WAV. */
+  public int getBytesPerSample() {
+    return blockAlignment / numChannels;
+  }
+
+  /** Returns the bitrate of this WAV. */
+  public int getBitrate() {
+    return sampleRateHz * bitsPerSample * numChannels;
+  }
+
+  /** Returns the sample rate in Hertz of this WAV. */
+  public int getSampleRateHz() {
+    return sampleRateHz;
+  }
+
+  /** Returns the number of audio channels in this WAV. */
+  public int getNumChannels() {
+    return numChannels;
+  }
+
+  /** Returns the position in bytes in this WAV for the given time in microseconds. */
+  public long getPosition(long timeUs) {
+    long unroundedPosition = (timeUs * averageBytesPerSecond) / C.MICROS_PER_SECOND;
+    // Round down to nearest frame.
+    return (unroundedPosition / numChannels) * numChannels + dataStartPosition;
+  }
+
+  /** Returns the time in microseconds for the given position in bytes in this WAV. */
+  public long getTimeUs(long position) {
+    return position * C.MICROS_PER_SECOND / averageBytesPerSecond;
+  }
+
+  /** Returns true if the data start position and size have been set. */
+  public boolean hasDataBounds() {
+    return dataStartPosition != 0 && dataSize != 0;
+  }
+
+  /** Sets the start position and size in bytes of sample data in this WAV. */
+  public void setDataBounds(long dataStartPosition, long dataSize) {
+    this.dataStartPosition = dataStartPosition;
+    this.dataSize = dataSize;
+  }
+}

library/src/main/java/com/google/android/exoplayer/extractor/wav/WavHeaderReader.java

@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer.extractor.wav;
+
+import com.google.android.exoplayer.ParserException;
+import com.google.android.exoplayer.extractor.ExtractorInput;
+import com.google.android.exoplayer.util.Assertions;
+import com.google.android.exoplayer.util.ParsableByteArray;
+import com.google.android.exoplayer.util.Util;
+
+import android.util.Log;
+
+import java.io.IOException;
+
+/** Reads a {@code WavHeader} from an input stream; supports resuming from input failures. */
+/*package*/ final class WavHeaderReader {
+
+  private static final String TAG = "WavHeaderReader";
+
+  /** Integer PCM audio data. */
+  private static final int TYPE_PCM = 0x0001;
+  /** Extended WAVE format. */
+  private static final int TYPE_WAVE_FORMAT_EXTENSIBLE = 0xFFFE;
+
+  /**
+   * Peeks and returns a {@code WavHeader}.
+   *
+   * @param input Input stream to peek the WAV header from.
+   * @throws IOException If peeking from the input fails.
+   * @throws InterruptedException If interrupted while peeking from input.
+   * @throws ParserException If the input file is an incorrect RIFF WAV.
+   * @return A new {@code WavHeader} peeked from {@code input}, or null if the input is not a
+   *     supported WAV format.
+   */
+  public static WavHeader peek(ExtractorInput input)
+      throws IOException, InterruptedException, ParserException {
+    Assertions.checkNotNull(input);
+
+    // Allocate a scratch buffer large enough to store the format chunk.
+    ParsableByteArray scratch = new ParsableByteArray(16);
+
+    // Attempt to read the RIFF chunk.
+    ChunkHeader riffChunkHeader = ChunkHeader.peek(input, scratch);
+    if (riffChunkHeader.id != Util.getIntegerCodeForString("RIFF")) {
+      return null;
+    }
+
+    input.peekFully(scratch.data, 0, 4);
+    scratch.setPosition(0);
+    int riffFormat = scratch.readInt();
+    if (riffFormat != Util.getIntegerCodeForString("WAVE")) {
+      Log.e(TAG, "Unsupported RIFF format: " + riffFormat);
+      return null;
+    }
+
+    // Attempt to read the format chunk.
+    ChunkHeader formatChunkHeader = ChunkHeader.peek(input, scratch);
+    if (formatChunkHeader.id != Util.getIntegerCodeForString("fmt ")) {
+      throw new ParserException(
+          "Second chunk in RIFF WAV should be format; got: " + formatChunkHeader.id);
+    }
+
+    input.peekFully(scratch.data, 0, 16);
+    scratch.setPosition(0);
+    int type = scratch.readLittleEndianUnsignedShort();
+    int numChannels = scratch.readLittleEndianUnsignedShort();
+    int sampleRateHz = scratch.readLittleEndianUnsignedIntToInt();
+    int averageBytesPerSecond = scratch.readLittleEndianUnsignedIntToInt();
+    int blockAlignment = scratch.readLittleEndianUnsignedShort();
+    int bitsPerSample = scratch.readLittleEndianUnsignedShort();
+
+    int expectedBlockAlignment = numChannels * bitsPerSample / 8;
+    if (blockAlignment != expectedBlockAlignment) {
+      throw new ParserException(
+          "Expected WAV block alignment of: "
+              + expectedBlockAlignment
+              + "; got: "
+              + blockAlignment);
+    }
+    if (bitsPerSample != 16) {
+      Log.e(TAG, "Only 16-bit WAVs are supported; got: " + bitsPerSample);
+      return null;
+    }
+
+    if (type == TYPE_PCM) {
+      Assertions.checkState(formatChunkHeader.size == 16);
+      // No more data to read.
+    } else if (type == TYPE_WAVE_FORMAT_EXTENSIBLE) {
+      Assertions.checkState(formatChunkHeader.size == 40);
+      // Skip extensionSize, validBitsPerSample, channelMask, subFormatGuid.
+      input.advancePeekPosition(2 + 2 + 4 + 16);
+    } else {
+      Log.e(TAG, "Unsupported WAV format type: " + type);
+      return null;
+    }
+
+    return new WavHeader(
+        numChannels, sampleRateHz, averageBytesPerSecond, blockAlignment, bitsPerSample);
+  }
+
+  /**
+   * Skips to the data in the given WAV input stream and returns its data size. After calling, the
+   * input stream's position will point to the start of sample data in the WAV.
+   * <p>
+   * If an exception is thrown, the input position will be left pointing to a chunk header.
+   *
+   * @param input Input stream to skip to the data chunk in. Its peek position must be pointing to
+   *     a valid chunk header that is not the RIFF chunk.
+   * @param wavHeader WAV header to populate with data bounds.
+   * @throws IOException If reading from the input fails.
+   * @throws InterruptedException If interrupted while reading from input.
+   * @throws ParserException If an error occurs parsing chunks.
+   */
+  public static void skipToData(ExtractorInput input, WavHeader wavHeader)
+      throws IOException, InterruptedException, ParserException {
+    Assertions.checkNotNull(input);
+    Assertions.checkNotNull(wavHeader);
+
+    ParsableByteArray scratch = new ParsableByteArray(ChunkHeader.SIZE_IN_BYTES);
+    // Skip all chunks until we hit the data header.
+    ChunkHeader chunkHeader = ChunkHeader.peek(input, scratch);
+    while (chunkHeader.id != Util.getIntegerCodeForString("data")) {
+      Log.w(TAG, "Ignoring unknown WAV chunk: " + chunkHeader.id);
+      long bytesToSkip = ChunkHeader.SIZE_IN_BYTES + chunkHeader.size;
+      if (bytesToSkip > Integer.MAX_VALUE) {
+        throw new ParserException("Chunk is too large (~2GB+) to skip; id: " + chunkHeader.id);
+      }
+      input.skipFully((int) bytesToSkip);
+      chunkHeader = ChunkHeader.peek(input, scratch);
+    }
+    // Skip past the "data" header.
+    input.skipFully(ChunkHeader.SIZE_IN_BYTES);
+
+    wavHeader.setDataBounds(input.getPosition(), chunkHeader.size);
+  }
+
+  /** Container for a WAV chunk header. */
+  private static final class ChunkHeader {
+
+    /** Size in bytes of a WAV chunk header. */
+    public static final int SIZE_IN_BYTES = 8;
+
+    /** 4-character identifier, stored as an integer, for this chunk. */
+    public final int id;
+    /** Size of this chunk in bytes. */
+    public final long size;
+
+    private ChunkHeader(int id, long size) {
+      this.id = id;
+      this.size = size;
+    }
+
+    /**
+     * Peeks and returns a {@link ChunkHeader}.
+     *
+     * @param input Input stream to peek the chunk header from.
+     * @param scratch Buffer for temporary use.
+     * @throws IOException If peeking from the input fails.
+     * @throws InterruptedException If interrupted while peeking from input.
+     * @return A new {@code ChunkHeader} peeked from {@code input}.
+     */
+    public static ChunkHeader peek(ExtractorInput input, ParsableByteArray scratch)
+        throws IOException, InterruptedException {
+      input.peekFully(scratch.data, 0, SIZE_IN_BYTES);
+      scratch.setPosition(0);
+
+      int id = scratch.readInt();
+      long size = scratch.readLittleEndianUnsignedInt();
+
+      return new ChunkHeader(id, size);
+    }
+  }
+}

library/src/main/java/com/google/android/exoplayer/util/ParsableByteArray.java

@@ -194,6 +194,13 @@ public final class ParsableByteArray {
         | (data[position++] & 0xFF);
   }
 
+  /** Reads the next three bytes as a signed value in little endian order. */
+  public int readLittleEndianInt24() {
+    return (data[position++] & 0xFF)
+        | (data[position++] & 0xFF) << 8
+        | (data[position++] & 0xFF) << 16;
+  }
+
   /**  Reads the next three bytes as an unsigned value in little endian order. */
   public int readLittleEndianUnsignedInt24() {
     return (data[position++] & 0xFF)
@@ -294,6 +301,20 @@ public final class ParsableByteArray {
     return result;
   }
 
+  /**
+   * Reads the next four bytes as a little endian unsigned integer into an integer, if the top bit
+   * is a zero.
+   *
+   * @throws IllegalStateException Thrown if the top bit of the input data is set.
+   */
+  public int readLittleEndianUnsignedIntToInt() {
+    int result = readLittleEndianInt();
+    if (result < 0) {
+      throw new IllegalStateException("Top bit not zero: " + result);
+    }
+    return result;
+  }
+
   /**
    * Reads the next eight bytes as an unsigned long into a long, if the top bit is a zero.
    *