Weird behaviour when seek operation is performed while playing preroll ad.

[sravan1213]

Steps to Reproduce.

1. Play any video with preroll.
2. Seek when player is in ready state. Please add following code in PlayerListener of demo app

 @Override
    public void onPlaybackStateChanged(@Player.State int playbackState) {
      if (playbackState == Player.STATE_READY) {
        player.seekTo(20_000);
      }
}

Observe player goes into weird state. Ad gets skipped and play randomly along with content.

100% reproducible on latest version of exo-player.

I understand exoplayer doesn't support seek during ads, but there is already a warning for this. performing this operation should not cause this issue.

[krocard]

I have added the seek on STATE_READY in the demo app but the seek was ignored as expected:

D/EventLogger: state [eventTime=0.90, mediaPos=0.00, window=0, period=0, adGroup=0, ad=0, READY]
D/EventLogger: seekStarted [eventTime=0.90, mediaPos=0.00, window=0, period=0, adGroup=0, ad=0]
W/ExoPlayerImpl: seekTo ignored because an ad is playing

Please provide the media with the prerolled media so we can reproduce and a bug report.

If you're unable to share bug reports or test content publicly, please send them to dev.exoplayer@gmail.com using a subject in the format "Issue #1234" ("#1234" is replaced with your issue number). Please also update this issue to indicate you've done this.

[sravan1213]

Hi @krocard ,

Attached video and logs for reference. In the video you can observe first preroll is completed before second preroll started and video got stuck at 1st mid-roll.

Also attaching patch for seek logic.

Hope this helps
issue_8349.zip

[krocard]

Thank you, I managed to reproduce the issue.

The issue is due to pendingOperationAcks being incremented even if the seek is ignored. When the seek is ignored, an updatedPlaybcak info is sent with an operationAcks of 0.

ExoPlayer/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java

Lines 598 to 607 in be13805

	pendingOperationAcks++;
	if (isPlayingAd()) {
	// TODO: Investigate adding support for seeking during ads. This is complicated to do in
	// general because the midroll ad preceding the seek destination must be played before the
	// content position can be played, if a different ad is playing at the moment.
	Log.w(TAG, "seekTo ignored because an ad is playing");
	playbackInfoUpdateListener.onPlaybackInfoUpdate(
	new ExoPlayerImplInternal.PlaybackInfoUpdate(playbackInfo));
	return;
	}

This lead to ExoPlayer considering that an operation is still in flight, and playbackInfo is no longer updated.

We could call incrementPendingOperationAcks(1) on the sent PlaybackInfoUpdate, but I'm not sure it is the right thing to do because it also sets hasPendingChange, which is not true.

This regression was introduced by b1e9257 in 2.12.0.

@icbaker could you take a look.