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.ExoTrackSelection;
  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, ExoTrackSelection[] 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 playbackPositionUs The current playback position in microseconds, relative to the start
     *     of the {@link Timeline.Period period} that will continue to be loaded if this method
     *     returns {@code true}. If playback of this period has not yet started, the value will be
     *     negative and equal in magnitude to the duration of any media in previous periods still to
     *     be played.
     * @param bufferedDurationUs The duration of media that's currently buffered.
     * @param playbackSpeed The current factor by which playback is sped up.
     * @return Whether the loading should continue.
     */
    boolean shouldContinueLoading(
        long playbackPositionUs, 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 factor by which playback is sped up.
     * @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.
     * @param targetLiveOffsetUs The desired playback position offset to the live edge in
     *     microseconds, or {@link C#TIME_UNSET} if the media is not a live stream or no offset is
     *     configured.
     * @return Whether playback should be allowed to start or resume.
     */
    boolean shouldStartPlayback(
        long bufferedDurationUs, float playbackSpeed, boolean rebuffering, long targetLiveOffsetUs);
  }
  