Alternate stream when primary isn't available

[Whsperz]

I don't know if I am in the right forum, so please move this if necessary. As the subject states, alternate stream if primary isn't available is what I am trying to accomplish with the alternate stream being just a jpg.

I have been tasked with trying to find a viable solution to monitor our multicast streams. Current command to just play each stream in small windows next to each other:

cvlc --width=200 --height=150 --sub-source="marq{marquee=Ch. 002 VOD Barker} udp://@235.1.1.2:2153 2&>1 --run-time 30 vlc:quit &
cvlc --width=200 --height=150 --sub-source="marq{marquee=Ch. 003 Local Weather} udp://@235.1.1.3:2153 2&>1 --run-time 30 vlc:quit &
and so on..

If one of the streams isn't running, then obviously the session will not open. Is there a way to an set an alternate command to play a JPG notifying anyone of trouble?

If I add the jpg file into the command line, it will play it after the stream is finished (i.e. after 30 seconds)
cvlc --width=200 --height=150 --sub-source="marq{marquee=Ch. 002 VOD Barker} udp://@235.1.1.2:2153 trouble.jpg 2&>1 --run-time 30 vlc:quit &

Any advice is welcome. Thank you for your time.