SimpleBasePlayer & Reference Material in General

[AttonRisk]

I'll be direct in asking why there isn't more reference implementation of classes like SimpleBasePlayer. I entirely understand not wanting to do that for the entire Player class, given extending it would involve some 120 methods or so. But I am kind stuck, in where I am attempting to sort of replace ExoPlayer with a SimpleBasePlayer class that plays nice with MediaSession. Think a sort of ExoPlayer drop in replacement that allows actual playback to be implemented by other means. Is there any chance of reference implementations or is that a pipe dream on my part?

[marcbaechinger]

Thanks for your question.

I've added the 'documentation candidate` label to this issue.

Implementing a SimpleBasePlayer from scratch is probably more work than using ForwardingSimpleBasePlayer that we added with the last release.

As far as I can tell this provides you with an easy start as you can start with delegating everything to ExoPlayer with the app having the option to get in between easily. Please see the class level JavaDoc for how to leverage for instance the getState() method of ForwardingSimpleBasePlayer and build upon it.

I think this makes implementing a SimpleBasePlayer much easier. I also think that documentation should start from there. We simply don't have the capacity to document implementing a SimpleBasePlayer from scratch.

But I am kind stuck, in where I am attempting to sort of

Just OOI what are the difficulties you are having and what documentation would help you?

replace ExoPlayer with a SimpleBasePlayer class that plays nice with MediaSession.

OOI again: can you spell out in more details and use case where ExoPlayer does not play nicely? I'm asking because that's interesting for us to hear to see whether we can fill these gaps else where.

[marcbaechinger]

Think a sort of ExoPlayer drop in replacement that allows actual playback to be implemented by other means

I was being made aware of this sentence above. So my advise with ForwardingSimpleBasePlayer is not really helpful. Please accept my apologies for not being attentive enough.

What is available regarding documentation about creating a SimpleBasePlayer is the JavaDoc and [1].

We'd still be curious to get your input on the questions above on what exact documentation would be helpful for you.

[1] https://developer.android.com/media/media3/session/player#custom

[AttonRisk]

In this context since there isn't a huge amount of boiler plate, I think this might be a good case for a reference implementation or demo.

[AttonRisk]

notright.csv
A pretty good example is this, I have no idea why its not playing nice with MediaSession and I have nothing to reference to find out why.

[marcbaechinger]

Thanks for the example.

I think it's a pretty good example indeed, that shows that the system as a whole is complicated when leaving well paved roads (for instance using ExoPlayer) and, please accept my apologies for contradicting your request, documentation for SimpleBasePlayer would not help for this example I'm afraid.

The actual problem you bring up here looks rather trivial compared to what implementing a Player means if I'm not mistaken. It is not a problem with your SimpleBasePlayer implementation I think. Instead, play is called when the player is empty and has no media items in the playlist yet. In such a case playback resumption tries to fullfill the play request as a last resort and it fails because your MediaSession.Callback implementation didn't override the playback resumption method.

It's a bit unclear from the available information, who has triggered this play command. I looks like the documentation on playback resumption is not sufficient or wasn't consulted.

So in case this play command was triggered by your app, a fix is not in yourSimpleBasePlayer implementation but rather that some media items need to be added to the player before playing. This can be achieved in many ways. For instance a) by adding the items from the MediaController or b) by simply setting up the player with a playlist of items at start so that a MediaController doesn't need to check the state to learn that the playlist is empty and calling play doesn't make much sense. If the MediaController that causes this isn't owned by your app and you have to expect that some external user do call play at any moment, then c) implementing MediaSession.Callback.onPlaybackResumption() would be a further fix as suggested by the error message in the stack trace.

Summarizing the reported stack trace, I don't think documentation for SimpleBasePlayer would help in this case because the system to manage is larger than just the player.

UnsupportedOperationException: Make sure to implement MediaSession.Callback.onPlaybackResumption() if you add a media button receiver to your manifest or if you implement the recent media item contract with your MediaLibraryService.
java.lang.UnsupportedOperationException
at androidx.media3.session.MediaSession$Callback.onPlaybackResumption(MediaSession.java:1751)
at androidx.media3.session.MediaSessionImpl.handleMediaControllerPlayRequest(MediaSessionImpl.java:992)
at androidx.media3.session.MediaSessionStub.lambda$playForControllerInfo$19$androidx-media3-session-MediaSessionStub(MediaSessionStub.java:740)
at androidx.media3.session.MediaSessionStub$$ExternalSyntheticLambda34.accept(D8$$SyntheticClass:0)
at androidx.media3.session.MediaSessionStub.lambda$sendSessionResultSuccess$0(MediaSessionStub.java:164)
at androidx.media3.session.MediaSessionStub$$ExternalSyntheticLambda68.run(D8$$SyntheticClass:0)
at androidx.media3.session.MediaSessionStub.lambda$sendSessionResultSuccess$1(MediaSessionStub.java:173)
at androidx.media3.session.MediaSessionStub$$ExternalSyntheticLambda84.run(D8$$SyntheticClass:0)
at androidx.media3.session.MediaSessionStub.lambda$queueSessionTaskWithPlayerCommandForControllerInfo$13(MediaSessionStub.java:343)
at androidx.media3.session.MediaSessionStub$$ExternalSyntheticLambda40.run(D8$$SyntheticClass:0)
at androidx.media3.session.ConnectedControllersManager.lambda$flushCommandQueue$3$androidx-media3-session-ConnectedControllersManager(ConnectedControllersManager.java:295)
at androidx.media3.session.ConnectedControllersManager$$ExternalSyntheticLambda0.run(D8$$SyntheticClass:0)
at androidx.media3.session.MediaSessionImpl.lambda$callWithControllerForCurrentRequestSet$3$androidx-media3-session-MediaSessionImpl(MediaSessionImpl.java:356)
at androidx.media3.session.MediaSessionImpl$$ExternalSyntheticLambda21.run(D8$$SyntheticClass:0)
at androidx.media3.common.util.Util.postOrRun(Util.java:798)
at androidx.media3.session.ConnectedControllersManager.flushCommandQueue(ConnectedControllersManager.java:289)
at androidx.media3.session.ConnectedControllersManager.flushCommandQueue(ConnectedControllersManager.java:270)
at androidx.media3.session.MediaSessionStub.lambda$flushCommandQueue$64$androidx-media3-session-MediaSessionStub(MediaSessionStub.java:1691)
at androidx.media3.session.MediaSessionStub$$ExternalSyntheticLambda37.run(D8$$SyntheticClass:0)
at androidx.media3.common.util.Util.postOrRun(Util.java:798)
at androidx.media3.session.MediaSessionStub.flushCommandQueue(MediaSessionStub.java:1689)
at androidx.media3.session.MediaControllerImplBase$FlushCommandQueueHandler.flushCommandQueue(MediaControllerImplBase.java:3521)
at androidx.media3.session.MediaControllerImplBase$FlushCommandQueueHandler.handleMessage(MediaControllerImplBase.java:3514)
at androidx.media3.session.MediaControllerImplBase$FlushCommandQueueHandler.$r8$lambda$TVKiXTCmsW2hn-6HNXqbaigkfJc(Unknown Source:0)
at androidx.media3.session.MediaControllerImplBase$FlushCommandQueueHandler$$ExternalSyntheticLambda0.handleMessage(D8$$SyntheticClass:0)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loopOnce(Looper.java:232)
at android.os.Looper.loop(Looper.java:317)
at android.app.ActivityThread.main(ActivityThread.java:8705)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:580)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:886)

Without further context I'd guess this happens when play is called from a MediaController without items in the playlist.

[AttonRisk]

It is more or less an attempt at a sort of drop in emulator in place of ExoPlayer basically designed to log the execution of commands like play and pause and seek. The code that connects to this extension of the Player class works fine as established in ExoPlayer but breaks entirely with SimpleBasePlayer. In principal I see nearly no examples in the wild of anything other than ExoPlayer being used, despite digging through github. VLC and I am pretty sure firefox remain on media2 and I imagine this might be in part why.