Decoder reuse in MediaSessionConnector

[AndrazP]

[REQUIRED] Searched documentation and issues

Recent Improved decoder reuse in ExoPlayer blog post explains how to make sure your app benefits from decoder reuse:

When re-preparing the player with a different video, call prepare() with the new MediaSource without calling stop() first. This is because by default, ExoPlayer will still release decoders when stop() is called.

I noticed MediaSessionConnector.java calls stopPlayerForPrepare(boolean playWhenReady) before preparing new source.

[REQUIRED] Question

Is there a reason why MediaSessionConnector calls player.stop() before preparing new source? Is this not against best practices for decoder reuse?

[ojw28]

Good question ;). I doubt there's a good reason... @marcbaechinger - Think we can safely remove the stop() call, and rename stopPlayerForPrepare to setPlayWhenReady? Or is there a reason those calls are there?

[tonihei]

Just to document the potential change in behavior after this change: A PlaybackPreparer which tries to start from a non-default start position may now fail if does not call player.stop() itself:

public void onPrepare() {
  player.seekTo(startPosition);
  player.prepare(newMediaSource, /* resetPosition */ false, /* resetState */ true);
}

That is because this seek will be treated as a seek in the old media due to the missing stop operation. This may (or may not) cause unexpected effects for the start position in the new media even if we keep the position. If that problem occurs, it can be fixed by calling player.stop(true) first in PlaybackPreparer methods.

[ojw28]

As discussed, we need a slightly bigger change to correctly handle all cases. Reopening.