How do I add static video to a call?

Problem: my conferencing software’s SIP bridge only supports calls with audio and video. Now we can all agree that this is broken – in fact I already emailed my opinion about this to their support – but in the meantime I need to figure out how to add a dummy video channel to an audio-only Asterisk call.

In Asterisk 16 with PJSIP you may be able to alter the codecs in the negotiation and use PJSIP_SESSION_REFRESH[1] to renegotiate and add a video stream. This doesn’t actually send out video packets though, I’m not sure if there really is a way to do that for static video…

This is very much in “off the beaten paths” territory.