android-34/com/google/android/exoplayer2/extractor/mp3/ConstantBitrateSeeker.java

/*
 * 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.mp3;

import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.audio.MpegAudioUtil;
import com.google.android.exoplayer2.extractor.ConstantBitrateSeekMap;

/**
 * MP3 seeker that doesn't rely on metadata and seeks assuming the source has a constant bitrate.
 */
/* package */ final class ConstantBitrateSeeker extends ConstantBitrateSeekMap implements Seeker {

  /**
   * @param inputLength The length of the stream in bytes, or {@link C#LENGTH_UNSET} if unknown.
   * @param firstFramePosition The position of the first frame in the stream.
   * @param mpegAudioHeader The MPEG audio header associated with the first frame.
   * @param allowSeeksIfLengthUnknown Whether to allow seeking even if the length of the content is
   *     unknown.
   */
  public ConstantBitrateSeeker(
      long inputLength,
      long firstFramePosition,
      MpegAudioUtil.Header mpegAudioHeader,
      boolean allowSeeksIfLengthUnknown) {
    // Set the seeker frame size to the size of the first frame (even though some constant bitrate
    // streams have variable frame sizes) to avoid the need to re-synchronize for constant frame
    // size streams.
    super(
        inputLength,
        firstFramePosition,
        mpegAudioHeader.bitrate,
        mpegAudioHeader.frameSize,
        allowSeeksIfLengthUnknown);
  }

  @Override
  public long getTimeUs(long position) {
    return getTimeUsAtPosition(position);
  }

  @Override
  public long getDataEndPosition() {
    return C.POSITION_UNSET;
  }
}