content: /*
   * 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.exoplayer2.extractor.wav;
  
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.extractor.SeekMap;
  import com.google.android.exoplayer2.extractor.SeekPoint;
  import com.google.android.exoplayer2.util.Util;
  
  /** Header for a WAV file. */
  /* package */ final class WavHeader implements SeekMap {
  
    /** 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;
    /** The PCM encoding */
    @C.PcmEncoding
    private final int encoding;
  
    /** 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, @C.PcmEncoding int encoding) {
      this.numChannels = numChannels;
      this.sampleRateHz = sampleRateHz;
      this.averageBytesPerSecond = averageBytesPerSecond;
      this.blockAlignment = blockAlignment;
      this.bitsPerSample = bitsPerSample;
      this.encoding = encoding;
    }
  
    // Setting bounds.
  
    /**
     * Sets the data start position and size in bytes of sample data in this WAV.
     *
     * @param dataStartPosition The data start position in bytes.
     * @param dataSize The data size in bytes.
     */
    public void setDataBounds(long dataStartPosition, long dataSize) {
      this.dataStartPosition = dataStartPosition;
      this.dataSize = dataSize;
    }
  
    /** Returns whether the data start position and size have been set. */
    public boolean hasDataBounds() {
      return dataStartPosition != 0 && dataSize != 0;
    }
  
    // SeekMap implementation.
  
    @Override
    public boolean isSeekable() {
      return true;
    }
  
    @Override
    public long getDurationUs() {
      long numFrames = dataSize / blockAlignment;
      return (numFrames * C.MICROS_PER_SECOND) / sampleRateHz;
    }
  
    @Override
    public SeekPoints getSeekPoints(long timeUs) {
      long positionOffset = (timeUs * averageBytesPerSecond) / C.MICROS_PER_SECOND;
      // Constrain to nearest preceding frame offset.
      positionOffset = (positionOffset / blockAlignment) * blockAlignment;
      positionOffset = Util.constrainValue(positionOffset, 0, dataSize - blockAlignment);
      long seekPosition = dataStartPosition + positionOffset;
      long seekTimeUs = getTimeUs(seekPosition);
      SeekPoint seekPoint = new SeekPoint(seekTimeUs, seekPosition);
      if (seekTimeUs >= timeUs || positionOffset == dataSize - blockAlignment) {
        return new SeekPoints(seekPoint);
      } else {
        long secondSeekPosition = seekPosition + blockAlignment;
        long secondSeekTimeUs = getTimeUs(secondSeekPosition);
        SeekPoint secondSeekPoint = new SeekPoint(secondSeekTimeUs, secondSeekPosition);
        return new SeekPoints(seekPoint, secondSeekPoint);
      }
    }
  
    // Misc getters.
  
    /**
     * Returns the time in microseconds for the given position in bytes.
     *
     * @param position The position in bytes.
     */
    public long getTimeUs(long position) {
      long positionOffset = Math.max(0, position - dataStartPosition);
      return (positionOffset * C.MICROS_PER_SECOND) / averageBytesPerSecond;
    }
  
    /** Returns the bytes per frame of this WAV. */
    public int getBytesPerFrame() {
      return blockAlignment;
    }
  
    /** 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 PCM encoding. **/
    public @C.PcmEncoding int getEncoding() {
      return encoding;
    }
  
  }
  