@Override
    public long getCachedDuration() {
        return mFutureCache.size() * mRepresentation.segmentDurationUs;
    }
Tries to switch to the next segment and returns true if there is one, false if there is none
and thus the current is the last one.
MediaPlayer-DASH/src/main/java/net/protyposis/android/mediaplayer/dash/DashMediaExtractor.java