Posted on by Mark Butler

Streaming a Window Without Hardware

Given what OBS does (screen grab and encode) it would seem that there should be a simple way to capture a window and create a local video stream from it. This could then be viewed remotely served from your home PC, or used as an input in the composition for a stream scene.

This is clearly done using a HW video capture device, but that is expensive and given everything is already digital, seems like an odd detour.

An example use case for this is if you were using a separate Windows laptop of tablet for drawing and wanted to be able include it in a Twitch stream. Web cameras do this and use the RTSP protocol. So I went looking for a simple way to set this up on a new machine.

OBS

The obvious choice might seem to be OBS as a producer of this. However this is a very large installation for a simple server encode. That said I tried to set this up and I did not have much success (OBS Studio 26.0.2). I was expecting to be able to set up a custom stream target and set the output encode to be:

rtsp://localhost:544/live

However this seemed to hang OBS.

OBS-RTSPServer

I then tried an OBS RTSP extension (OBS-RTSPServer 1.1.3) which did work nicely:

https://obsproject.com/forum/resources/obs-rtspserver.1037/

VLC

Given this is installed on all the machines and that it also should provide RTSP support. I tried this. However I could not get it working.

So… there still seems like there should be a simpler solution.

happytime-rtsp-server-x64

This is the sort of thing I was looking for. It was a simple, small, standalone programme that could act as a screen grabber and an RTSP server. The setup was very simple:

  1. Download from http://www.happytimesoft.com/products/rtsp-server/index.html
  2. Unzip
  3. Update config.xml
  4. Run RtspServer.exe

Here are some pros and cons:

  • It allowed for password protection which is nice
  • It only grabs the full screen.
    • The work around is to crop and resize in the compositing OBS scene.
  • There is a long latency.
    • This might not matter if you are sketching something for the viewers.

Summary

So there are solutions that are close, but not really the obvious simple service to provide real time, named window capture, and encode to as an RTSP stream from the local PC.