We are currently using ExoPlayer for one of our applications, which is very similar to the HQ Trivia app, and we use HLS as the streaming protocol.
Due to the nature of the game, we are trying to keep all the viewers of this stream to have the same latency, basically to keep them in sync.
We noticed that with the current backend configuration the latency is somewhere between 6 and 10 seconds. Based on this fact, we assumed that it would be safe to “force” the player to play at a bigger delay (15 seconds, further off the live edge), this way achieving the same (constant) delay across all the devices.
We’re using EXT-X-PROGRAM-DATE-TIME tag to get the server time of the currently playing content and we also have a master clock with the current time (NTP). We’re constantly comparing the 2 clocks to check the current latency. We’re pausing the player until it reaches the desired delay, then we’re resuming the playback.
The problem with this solution is that the latency might get worse (accumulating delay) over time and we don’t have other choice than restarting the playback and redo the steps described above if the delay gets too big (steps over a specified threshold). Before restarting the player we’re also trying to slightly increase the playback speed until it reaches the specified delay.
The exoPlayer instance is setup with a DefaultLoadControl, DefaultRenderersFactory, DefaultTrackSelector and the media source uses a DefaultDataSourceFactory.
The server-side configuration is as follows: cupertinoChunkDurationTarget: 2000 (default: 10000) cupertinoMaxChunkCount: 31 (default: 10) cupertinoPlaylistChunkCount: 15 (default: 3)
My first question would be if this is even achievable with a protocol like HLS? Why is the player drifting away accumulating more and more delay? Is there a better setup for the exoPlayer instance considering our specific use case? Is there a better way to achieve a constant playback delay across all the playing devices? How important are the parameters on the server side in trying to achieve such a behaviour?
I would really appreciate any kind of help because I have reached a dead-end. :)
Thanks!
