content: /*
   * Copyright (C) 2019 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;
  
  /* package */ final class WavSeekMap implements SeekMap {
  
    private final WavFormat wavFormat;
    private final int framesPerBlock;
    private final long firstBlockPosition;
    private final long blockCount;
    private final long durationUs;
  
    public WavSeekMap(
        WavFormat wavFormat, int framesPerBlock, long dataStartPosition, long dataEndPosition) {
      this.wavFormat = wavFormat;
      this.framesPerBlock = framesPerBlock;
      this.firstBlockPosition = dataStartPosition;
      this.blockCount = (dataEndPosition - dataStartPosition) / wavFormat.blockSize;
      durationUs = blockIndexToTimeUs(blockCount);
    }
  
    @Override
    public boolean isSeekable() {
      return true;
    }
  
    @Override
    public long getDurationUs() {
      return durationUs;
    }
  
    @Override
    public SeekPoints getSeekPoints(long timeUs) {
      // Calculate the containing block index, constraining to valid indices.
      long blockIndex = (timeUs * wavFormat.frameRateHz) / (C.MICROS_PER_SECOND * framesPerBlock);
      blockIndex = Util.constrainValue(blockIndex, 0, blockCount - 1);
  
      long seekPosition = firstBlockPosition + (blockIndex * wavFormat.blockSize);
      long seekTimeUs = blockIndexToTimeUs(blockIndex);
      SeekPoint seekPoint = new SeekPoint(seekTimeUs, seekPosition);
      if (seekTimeUs >= timeUs || blockIndex == blockCount - 1) {
        return new SeekPoints(seekPoint);
      } else {
        long secondBlockIndex = blockIndex + 1;
        long secondSeekPosition = firstBlockPosition + (secondBlockIndex * wavFormat.blockSize);
        long secondSeekTimeUs = blockIndexToTimeUs(secondBlockIndex);
        SeekPoint secondSeekPoint = new SeekPoint(secondSeekTimeUs, secondSeekPosition);
        return new SeekPoints(seekPoint, secondSeekPoint);
      }
    }
  
    private long blockIndexToTimeUs(long blockIndex) {
      return Util.scaleLargeTimestamp(
          blockIndex * framesPerBlock, C.MICROS_PER_SECOND, wavFormat.frameRateHz);
    }
  }
  