mpromonet/v4l2rtspserver ? reverse-engineered prompt

Build me a small C++ app that turns a V4L2 camera into an RTSP stream, with optional audio from an ALSA device too.

It should let me point it at one or more devices like a webcam or microphone, then stream them over RTSP in a way that works with normal players. Support video formats like H264, HEVC, JPEG, VP8, and VP9 if the device provides them, and let me choose whether I want one combined stream or separate audio and video streams.

I also want a simple HTTP mode for HLS and MPEG DASH when the stream can be packaged that way, plus a basic web page I can open in a browser to test playback. Make it easy to run from the command line with options for port, device, resolution, framerate, username and password, and multicast or unicast. If you need to check current docs for live555 or any related libraries, do that.