Take snapshot through URL

[filamonkey]

I have built a rPi Camera to monitor my 3D printers using mediamtx an rPi zero 2W. For this purpose, it works great. When defining the camera in Mainsail (front end to control the printers) you define both a stream URL (just used IP:8889/mycam) and a snapshot URL so you can do a timelapse with Moonraker (the underlying web server) while the toolhead is parked at a specified point.
I haven't managed to set this up. I have tried this:

mycam: source: rpiCamera snapshot: runOnRead: ffmpeg -i rtsp://localhost:8554/cam -frames 1 -y /tmp/out.jpg runOnReadRestart: yes

I have also tried runOnDemand with no luck.
Is there a way to accomplish this?

[eprouty]

So this is a bit hacky... would love to know a better way to do this, but it's working for anyone else that needs this:

Setup ffmpeg to produce a new snapshot jpg by adding the following to your cam: definition. This will update the snapshot every X seconds as defined by the -r flag, for this example it's 1 fps:

    runOnReady: ffmpeg -i rtsp://localhost:8554/cam -r 1 -update 1 -y /home/eprouty/mainsail/snapshot.jpg
    runOnReadyRestart: yes

This snapshot gets stored in your mainsail directory which Nginx should already be setup to serve files from. So now if you go to http://your.mainsail.addr/snapshot.jpg, it should serve you the most recent snapshot. That file will be continually over written in the background so this does require a decent bit of cpu.

Now as long as you tune the -r to be frequent enough to always have a new image for you, than you should be able to do timelapses.