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;
  
  import com.google.android.exoplayer2.source.TrackGroup;
  import com.google.android.exoplayer2.source.TrackGroupArray;
  import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
  import com.google.android.exoplayer2.upstream.Allocator;
  
  /**
   * Controls buffering of media.
   */
  public interface LoadControl {
  
    /**
     * Called by the player when prepared with a new source.
     */
    void onPrepared();
  
    /**
     * Called by the player when a track selection occurs.
     *
     * @param renderers The renderers.
     * @param trackGroups The {@link TrackGroup}s from which the selection was made.
     * @param trackSelections The track selections that were made.
     */
    void onTracksSelected(Renderer[] renderers, TrackGroupArray trackGroups,
        TrackSelectionArray trackSelections);
  
    /**
     * Called by the player when stopped.
     */
    void onStopped();
  
    /**
     * Called by the player when released.
     */
    void onReleased();
  
    /**
     * Returns the {@link Allocator} that should be used to obtain media buffer allocations.
     */
    Allocator getAllocator();
  
    /**
     * Returns the duration of media to retain in the buffer prior to the current playback position,
     * for fast backward seeking.
     * <p>
     * Note: If {@link #retainBackBufferFromKeyframe()} is false then seeking in the back-buffer will
     * only be fast if the back-buffer contains a keyframe prior to the seek position.
     * <p>
     * Note: Implementations should return a single value. Dynamic changes to the back-buffer are not
     * currently supported.
     *
     * @return The duration of media to retain in the buffer prior to the current playback position,
     *     in microseconds.
     */
    long getBackBufferDurationUs();
  
    /**
     * Returns whether media should be retained from the keyframe before the current playback position
     * minus {@link #getBackBufferDurationUs()}, rather than any sample before or at that position.
     * <p>
     * Warning: Returning true will cause the back-buffer size to depend on the spacing of keyframes
     * in the media being played. Returning true is not recommended unless you control the media and
     * are comfortable with the back-buffer size exceeding {@link #getBackBufferDurationUs()} by as
     * much as the maximum duration between adjacent keyframes in the media.
     * <p>
     * Note: Implementations should return a single value. Dynamic changes to the back-buffer are not
     * currently supported.
     *
     * @return Whether media should be retained from the keyframe before the current playback position
     * minus {@link #getBackBufferDurationUs()}, rather than any sample before or at that position.
     */
    boolean retainBackBufferFromKeyframe();
  
    /**
     * Called by the player to determine whether it should continue to load the source.
     *
     * @param bufferedDurationUs The duration of media that's currently buffered.
     * @param playbackSpeed The current playback speed.
     * @return Whether the loading should continue.
     */
    boolean shouldContinueLoading(long bufferedDurationUs, float playbackSpeed);
  
    /**
     * Called repeatedly by the player when it's loading the source, has yet to start playback, and
     * has the minimum amount of data necessary for playback to be started. The value returned
     * determines whether playback is actually started. The load control may opt to return {@code
     * false} until some condition has been met (e.g. a certain amount of media is buffered).
     *
     * @param bufferedDurationUs The duration of media that's currently buffered.
     * @param playbackSpeed The current playback speed.
     * @param rebuffering Whether the player is rebuffering. A rebuffer is defined to be caused by
     *     buffer depletion rather than a user action. Hence this parameter is false during initial
     *     buffering and when buffering as a result of a seek operation.
     * @return Whether playback should be allowed to start or resume.
     */
    boolean shouldStartPlayback(long bufferedDurationUs, float playbackSpeed, boolean rebuffering);
  }
  