And as we suspect, these proprietary extensions will require some (unknown :)) time to be updated to use media3.

media3 contains pretty much everything that exoplayer2 does - the only catch is that some classes have moved between packages. I suspect it wouldn't actually be that hard to migrate these extensions to work with media3 - it should basically just be a case of resolving compilation failures caused by classes moving around.

So far we decided to continue to use old com.google.android.ExoPlayer that works fine with our extensions and plug that into Media3 MediaSession by creating an adapter. That adapter would implement androidx.media3.common.Player, proxying calls to a wrapped com.google.android.ExoPlayer. However, this is going to be really cumbersome due to lots of conversions of objects.

Is there any chance that some compatibility tool will be provided or should we go with the described adapter?

We don't have any plans to create a tool to convert objects between exoplayer2 and media3 at runtime.

Or maybe there's even a better & recommended way to do this?

I think you're better off migrating everything to media3, rather than trying to use both exoplayer2 and media3 concurrently in the same project.

yep, that absolutely makes sense that migrating the extensions should be as simple as changing the package, but that should be done by our vendors. we'll try to push them, but anyway, it's our call now.

Thanks!