How can I script video playback with output to multiple screens?

Question

Background

I'm attempting to craft a simple video playback script for a small cinema that automates the playing of videos and control of the projector, sound and lighting systems. I have two video outputs, one goes to a monitor in the projection booth, and the other directly to the projector. I desire to play video (and only video) fullscreen to the projector while putting controls and a small (~1/4 screen) preview on the monitor. This will allow the projectionist to view the video being output and control the playback from the monitor in the booth while all the audience ever sees is the video output.

Problem

I am currently using Python to control VLC player (with libvlc Python bindings) to playback videos. I have everything working fine except that I can't figure out how to get a preview (direct copy) of the video being played fullscreen on the projector output into my GUI.

I have tried using the clone filter, but I cant get the cloned window to automagically appear full screen nor in my GUI. The clone filter seems like the logical choice but it seems to be VERY inflexible when it comes to specifying destination screens, fullscreen, etc. I must be able to open video windows full screen on the projector monitor. Professionalism is key and it would look bad if the projectionist had to drag a window over and double click on it when the movie started.

Currently Using:

• Debian Linux
• Python 2.7
• wxPython
• libvlc

I would like to continue using Python as I already have the code for controlling the projector, sound processor, lighting and curtain written and tested. I chose VLC because it really seems bulletproof when it comes to video playback but am not committed to it's continued use. I also chose wxWidgets for my GUI as a result of past experience but I am not stuck on that either.

Answer 1

This describes the direct solution and does not concentrate on any alternative or the overall design of your application.

As Your Application and VLC media player are separate processes, you will not be able to get what you want directly because there is no "shared memory" between those 2 applications. The best shot to "copy" the decoded frames from VLC will be to e.g. send a RAW Video .mts stream (ts is usually used for this kind of usecase) and send e.g. to udp://localhost:1234.

In your application, you will need to be able to receive the ts stream, "decode" it and display at the spot of interest.

For start, i would try if you are able to do this using 2 vlc players that you control manually. When you achieved that the first VLC streams to udp and outputs on the main display at the same time, and the other VLC player receives and plays the udp stream you can go on:

Find a player library that you can use directly in your wxpython application and check if it can receive the udp stream as well E.g.

https://wxpython.org/Phoenix/docs/html/wx.media.MediaCtrl.html

This player lib for example requires gstreamer as a base.

As a result, main display and the picture in your applicatoin might have a latency of some seconds. To come around this latency, the best way that i currently know is using WebRTC but this is a lot more complex setup than the above.

https://www.sipwise.org/news/technical/tv-over-webrt/

Sure in case you do some "encoding" for WebRTC or even for UDP, you would need to utilize some hardware encoder, e.g. Nvidia NVENC in order to be able to guarantee the needed resources are always there.