The VideoLAN Forums

Right now, if a video file has two video tracks and you want to play both of them, the second tracks shows in a separate pop-up window. There seems to be no easy way to show both tracks side-by-side in the same window, at least not without fussing with the mosaic filter. I would like to simply have both tracks in the same window, as shown below:



It would be really cool if we could even play more than two tracks in the same window and drag them around to our preferred arrangement, but that would just be icing on the cake. I'm hoping that since we can play two tracks in two windows, it wouldn't be difficult to include an option to play two tracks in one window.

Maybe GridPlayer is what you're looking for:
https://github.com/vzhd1701/gridplayer

It is based on VLC.

I'm hoping that since we can play two tracks in two windows, it wouldn't be difficult to include an option to play two tracks in one window.

That's a bit of an overstatement unfortunately. Being able to play N track in N windows doesn't bring the "compositing" feature needed for this, nor the infrastructure to bring the stream together in a maintainable way.

As I wrote in your previous thread, this can be done with a custom module that you would have to write. But that module would have to be specific to your windowing system of choice...