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

/*
 * 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.mp3;

import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.extractor.SeekMap;

/**
 * {@link SeekMap} that provides the end position of audio data and also allows mapping from
 * position (byte offset) back to time, which can be used to work out the new sample basis timestamp
 * after seeking and resynchronization.
 */
/* package */ interface Seeker extends SeekMap {

  /**
   * Maps a position (byte offset) to a corresponding sample timestamp.
   *
   * @param position A seek position (byte offset) relative to the start of the stream.
   * @return The corresponding timestamp of the next sample to be read, in microseconds.
   */
  long getTimeUs(long position);

  /**
   * Returns the position (byte offset) in the stream that is immediately after audio data, or
   * {@link C#POSITION_UNSET} if not known.
   */
  long getDataEndPosition();

  /** A {@link Seeker} that does not support seeking through audio data. */
  /* package */ class UnseekableSeeker extends SeekMap.Unseekable implements Seeker {

    public UnseekableSeeker() {
      super(/* durationUs= */ C.TIME_UNSET);
    }

    @Override
    public long getTimeUs(long position) {
      return 0;
    }

    @Override
    public long getDataEndPosition() {
      // Position unset as we do not know the data end position. Note that returning 0 doesn't work.
      return C.POSITION_UNSET;
    }
  }
}