Play and split video on a wall of screens

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I am working on an Android TV app project. I need to split one video into 2, 3 or X screens in equal parts. Each screen has an Android TV stick plugged on it with my app on it. For example: If we have 2 screens each one will show 50% of the video played. If we have 3 screens each one will show 33,33% of the video played. If we have 4 screens each one will show 25% of the video played.

Here is one image to have a better understanding of my expectations:

screen walls

The video is played simultaneously in each screens of the wall and about this point I have already think about it : one screen will be the NTP (network time protocol) master and the other screen(s) will be the slave(s). To synchronize the players.

My first idea is to have on each app the complete video, playing it and having visible only the part that I need. How can I achieve that ? Is it possible ?

In advance thank you for your help.

android-tv kotlin android-layout logic android
1 Answers

I'm not clear how you'll handle the height (e.g., if you have a 1080p video but span it across four screens, you're going to have to cut off 3/4 of the pixels to "zoom in" on it across the screens), but some thoughts:

If you don't have to worry about HDCP, an HDMI splitter might work. If not, but it's for a one-off event (e.g., setting up a kiosk for a trade show), then it's probably least risky and easiest to create separate video files with them actually split how you'd want. If this has to be more flexible/robust, then it's going to be a bit of a journey with some options.

Simplest

You should be able to set up a SurfaceView as large as you need with the offsets adjusted for each device. For example, screen 2 might have a SurfaceView set with a width of #_of_screens * 1920 (or whatever the appropriate resolution is) and an X starting position of -1920. The caveat is that I don't know how large of a SurfaceView this could support. For example, this might work great for just two screens but not work for ten screens.

You can try using VIDEO_SCALING_MODE_SCALE_TO_FIT_WITH_CROPPING to scale the video output based on how big you need it to display.

For powerful devices

If the devices you're working with are powerful enough, you may be able to render to a SurfaceTexture off screen then copy the portion of the texture to a GLSurfaceView. If this is DRMed content, you'll also have to check for the EGL_EXT_protected_content extension.

For Android 10+

If the devices are running Android 10 or above, SurfaceControl may work for you. You can use a SurfaceControl.Transaction to manipulate the SurfaceControl, including the way the buffer coordinates are mapped. The basic code ends up looking like this:

new SurfaceControl.Transaction()
    .setGeometry(surfaceControl, sourceRect, destRect, Surface.ROTATION_0)
    .apply();

There's also a SurfaceControl sample in the ExoPlayer v2 demos: https://github.com/google/ExoPlayer/tree/release-v2/demos/surface

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