Class AdaptiveTrackSelection

    • Field Detail

      • DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS

        public static final int DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS
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        Constant Field Values
      • DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS

        public static final int DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS
        See Also:
        Constant Field Values
      • DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS

        public static final int DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS
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        Constant Field Values
      • DEFAULT_BANDWIDTH_FRACTION

        public static final float DEFAULT_BANDWIDTH_FRACTION
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        Constant Field Values
      • DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE

        public static final float DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE
        See Also:
        Constant Field Values
    • Constructor Detail

      • AdaptiveTrackSelection

        public AdaptiveTrackSelection​(TrackGroup group,
                                      int[] tracks,
                                      BandwidthMeter bandwidthMeter)
        Parameters:
        group - The TrackGroup.
        tracks - The indices of the selected tracks within the TrackGroup. Must not be empty. May be in any order.
        bandwidthMeter - Provides an estimate of the currently available bandwidth.
      • AdaptiveTrackSelection

        protected AdaptiveTrackSelection​(TrackGroup group,
                                         int[] tracks,
                                         int type,
                                         BandwidthMeter bandwidthMeter,
                                         long minDurationForQualityIncreaseMs,
                                         long maxDurationForQualityDecreaseMs,
                                         long minDurationToRetainAfterDiscardMs,
                                         float bandwidthFraction,
                                         float bufferedFractionToLiveEdgeForQualityIncrease,
                                         List<AdaptiveTrackSelection.AdaptationCheckpoint> adaptationCheckpoints,
                                         Clock clock)
        Parameters:
        group - The TrackGroup.
        tracks - The indices of the selected tracks within the TrackGroup. Must not be empty. May be in any order.
        type - The type that will be returned from TrackSelection.getType().
        bandwidthMeter - Provides an estimate of the currently available bandwidth.
        minDurationForQualityIncreaseMs - The minimum duration of buffered data required for the selected track to switch to one of higher quality.
        maxDurationForQualityDecreaseMs - The maximum duration of buffered data required for the selected track to switch to one of lower quality.
        minDurationToRetainAfterDiscardMs - When switching to a track of significantly higher quality, the selection may indicate that media already buffered at the lower quality can be discarded to speed up the switch. This is the minimum duration of media that must be retained at the lower quality. It must be at least minDurationForQualityIncreaseMs.
        bandwidthFraction - The fraction of the available bandwidth that the selection should consider available for use. Setting to a value less than 1 is recommended to account for inaccuracies in the bandwidth estimator.
        bufferedFractionToLiveEdgeForQualityIncrease - For live streaming, the fraction of the duration from current playback position to the live edge that has to be buffered before the selected track can be switched to one of higher quality. This parameter is only applied when the playback position is closer to the live edge than minDurationForQualityIncreaseMs, which would otherwise prevent switching to a higher quality from happening.
        adaptationCheckpoints - The checkpoints that can be used to calculate available bandwidth for this selection.
        clock - The Clock.
    • Method Detail

      • onPlaybackSpeed

        public void onPlaybackSpeed​(float playbackSpeed)
        Description copied from interface: ExoTrackSelection
        Called to notify the selection of the current playback speed. The playback speed may affect adaptive track selection.
        Specified by:
        onPlaybackSpeed in interface ExoTrackSelection
        Overrides:
        onPlaybackSpeed in class BaseTrackSelection
        Parameters:
        playbackSpeed - The factor by which playback is sped up.
      • updateSelectedTrack

        public void updateSelectedTrack​(long playbackPositionUs,
                                        long bufferedDurationUs,
                                        long availableDurationUs,
                                        List<? extends MediaChunk> queue,
                                        MediaChunkIterator[] mediaChunkIterators)
        Description copied from interface: ExoTrackSelection
        Updates the selected track for sources that load media in discrete MediaChunks.

        This method will only be called when the selection is enabled.

        Parameters:
        playbackPositionUs - The current playback position in microseconds. If playback of the period to which this track selection belongs has not yet started, the value will be the starting position in the period minus the duration of any media in previous periods still to be played.
        bufferedDurationUs - The duration of media currently buffered from the current playback position, in microseconds. Note that the next load position can be calculated as (playbackPositionUs + bufferedDurationUs).
        availableDurationUs - The duration of media available for buffering from the current playback position, in microseconds, or C.TIME_UNSET if media can be buffered to the end of the current period. Note that if not set to C.TIME_UNSET, the position up to which media is available for buffering can be calculated as (playbackPositionUs + availableDurationUs).
        queue - The queue of already buffered MediaChunks. Must not be modified.
        mediaChunkIterators - An array of MediaChunkIterators providing information about the sequence of upcoming media chunks for each track in the selection. All iterators start from the media chunk which will be loaded next if the respective track is selected. Note that this information may not be available for all tracks, and so some iterators may be empty.
      • getSelectedIndex

        public int getSelectedIndex()
        Description copied from interface: ExoTrackSelection
        Returns the index of the selected track.
      • getSelectionReason

        public int getSelectionReason()
        Description copied from interface: ExoTrackSelection
        Returns the reason for the current track selection.
      • getSelectionData

        @Nullable
        public Object getSelectionData()
        Description copied from interface: ExoTrackSelection
        Returns optional data associated with the current track selection.
      • evaluateQueueSize

        public int evaluateQueueSize​(long playbackPositionUs,
                                     List<? extends MediaChunk> queue)
        Description copied from interface: ExoTrackSelection
        Returns the number of chunks that should be retained in the queue.

        May be called by sources that load media in discrete MediaChunks and support discarding of buffered chunks.

        To avoid excessive re-buffering, implementations should normally return the size of the queue. An example of a case where a smaller value may be returned is if network conditions have improved dramatically, allowing chunks to be discarded and re-buffered in a track of significantly higher quality. Discarding chunks may allow faster switching to a higher quality track in this case.

        Note that even if the source supports discarding of buffered chunks, the actual number of discarded chunks is not guaranteed. The source will call ExoTrackSelection.updateSelectedTrack(long, long, long, List, MediaChunkIterator[]) with the updated queue of chunks before loading a new chunk to allow switching to another quality.

        This method will only be called when the selection is enabled and none of the MediaChunks in the queue are currently loading.

        Specified by:
        evaluateQueueSize in interface ExoTrackSelection
        Overrides:
        evaluateQueueSize in class BaseTrackSelection
        Parameters:
        playbackPositionUs - The current playback position in microseconds. If playback of the period to which this track selection belongs has not yet started, the value will be the starting position in the period minus the duration of any media in previous periods still to be played.
        queue - The queue of buffered MediaChunks. Must not be modified.
        Returns:
        The number of chunks to retain in the queue.
      • canSelectFormat

        protected boolean canSelectFormat​(Format format,
                                          int trackBitrate,
                                          long effectiveBitrate)
        Called when updating the selected track to determine whether a candidate track can be selected.
        Parameters:
        format - The Format of the candidate track.
        trackBitrate - The estimated bitrate of the track. May differ from Format.bitrate if a more accurate estimate of the current track bitrate is available.
        effectiveBitrate - The bitrate available to this selection.
        Returns:
        Whether this Format can be selected.
      • shouldEvaluateQueueSize

        protected boolean shouldEvaluateQueueSize​(long nowMs,
                                                  List<? extends MediaChunk> queue)
        Called from evaluateQueueSize(long, List) to determine whether an evaluation should be performed.
        Parameters:
        nowMs - The current value of Clock.elapsedRealtime().
        queue - The queue of buffered MediaChunks. Must not be modified.
        Returns:
        Whether an evaluation should be performed.
      • getMinDurationToRetainAfterDiscardUs

        protected long getMinDurationToRetainAfterDiscardUs()
        Called from evaluateQueueSize(long, List) to determine the minimum duration of buffer to retain after discarding chunks.
        Returns:
        The minimum duration of buffer to retain after discarding chunks, in microseconds.