I have 4 cameras on a remote site with limited computer resources and internet connection over cellular (4G so its not too bad, but not good either). I have OpenVPN connection to this site, so I can access everything like it was in the LAN.
The four RTSP streams are rtsp://192.168.XXX.YYY:554/cam/realmonitor?channel=N&subtype=0 (N=0..3), each is 2304x1296@25fps.
I'd like to combine these 4 streams to one mosaic, and make it available over the limited bandwidth connection (inside the VPN tunnel, so no public access). I'd like a solution where I can adjust the mosaic fps and resolution and experiment what gives me best results.
All four streams can have same resolution in the mosaic, and I'd like to maintain the aspect ratio. All streams have audio (16bit PCM @8kHz), and having the audio (combined from all 4 streams) in the mosaic would be nice, but not mandatory.
I have can put a Raspberry Pi (model 2 I have, can probably get model 3 or even 4 if needed) to ingest the "raw" RTSP streams, and make the mosaic. Raspis run RaspiOS (i.e. Debian), no display/keyboard, just ssh access.
The site also has a Windows 10 computer that is on 24/7, and it has more performance (Intel 4th gen 4-core processor, 32GB ram etc.) that could also be used, if Raspi performance is not enough. This Windows box has a display and keyboard/mouse.
Connections inside the site are good, but the Internet connection is not 100% reliable. Whatever the solution is, it should tolerate mosaic streaming problems. I assume this is more like "restart the off-site mosaic stream client" but it it impacts how the mosaic is done or made available, thought this should be mentioned.
What basic options should I consider? Do the mosaic in Raspi/Linux or PC/Windows? Which programs (e.g. ffmpeg, vlc) should I look first? Links to "been there, done that"?