SimplePool for Exoplayer

[yoobi]

Describe your question in detail:

Hello, my application use extensively Exoplayer and I wanted to make some improvement for my users ( ~440 000 users with phone from API 21 to API 26).

For context my app is just like Youtube, so users browse between pages which result in an ever-ending cycle of:

1. creating Exoplayer
2. setting mediaSource + listeners
3. playing/pausing
4. removing listener + releasing Exoplayer

I was wondering if creating/releasing player is more resource-consuming than creating a Pool with 2 instances of Exoplayer? What's your opinion about using a SimplePool<Exoplayer>(2) ?

[marcbaechinger]

Using a pool of player can make sense for some use cases. I wouldn't think about performance in the sense opf resources required to create the players. It is certainly needs a bit more resources to recreate new instances, but I would focus on performance only in the sense of user experience. That is, if you want to play two videos in a RecyclerView or a ViewPager and the surfaces on which the video is rendered are visible at the same time, then you possibly need two players to be able to have at least one frame rendered on each of the surfaces. In general, if your app needs to decode two videos at the same time, you need multiple instances.

However, if you do that you need to take care of some low-level devices possibly do not support multiple instances of the video codec being used at the same time. So it gets a bit more complicated.

In general I would say if there is no need in terms of user experience I would stick with a single instance for simplicity. But I think in your case it can make sense to use a pool.

This is an advanced problem to solve properly and people asked question around this quite a lot. So it also makes sense to search the existing issues a bit to learn how other users solved this problem. An example issue about how to use the player in a RecyclerView is #867.

[yoobi]

Thank you for your detailed answer ! My issue is not really caused by a RecyclerView or ViewPager albeit it can relate in a sense.

Let's say we have VideoPageFragment which creates a new Exoplayer instance in fun onStart() and destroy the instance in onStop(). Therefore there is only one instance of Exoplayer at a time.

1. User browse toVideoPageFragment to watch a video called: "Building Exoplayer Part 1"
2. User clicks on button "Next", hence destroying the last VideoPageFragment and creating a new VideoPageFragment with data of the next video.
3. User close the app

With this simple 3-step example, the user has created and destroyed 2 instance of Exoplayer. Would using a Pool make sense for such a case ?

[yoobi]

Do you have some advice ?

[marcbaechinger]

I understand there is only one fragment active and only one instance playing at a time that can be shared by these fragments. I think in this case I would just have a single instance that is created in the activity, that you can use from the fragment by using ((ExoPlayerHostingActivity)getActivity()).getPlayer(). The fragments lifecycle methods can then be used to set media sources, prepare the player and start playback. Afterwards the player is pause, stopped and released. For such a use case without overlapping playback a single instance sounds sufficient.

[yoobi]

I'm ashamed to say I didn't think of that because this is simple and brilliant. I'll go with that instead of doing a pool.

Thanks