Picture in picture encoder

Basicly, we want something that does what we currently do using OBS studio:

• define position, size and origin for data sources: background image, camera, slides and logo image
• define streaming targets: rtmp servers, ...
• ingest from something running on the video boxes (mistserver, ffmpeg, a thin wrapper around ffmpeg, whatever...)
• create a fixed picture-in-picture from this, like https://www.youtube.com/watch?v=YQJUlUdQfZc
• push this PiP stream to a decent external server. Youtube is not an option, so nginx-rtmp or similar might be an option. Nginx might be interesting because of the great http_mp4 module...

It would be really really useful to get visual feedback on the video box lcd screens:

• (wall clock timestamped) (snapshots from) the picture-in-picture stream
• ? (PiP stream) audio volume
• current date
• box ip adress

##Various links to be categorised

• http://unix.stackexchange.com/questions/283343/remote-headless-streaming-of-gui-from-linux-x-says-no-protocol-specified-befo
• http://askubuntu.com/questions/453109/add-fake-display-when-no-monitor-is-plugged-in
• https://obsproject.com/forum/threads/start-stream-automatically.47824/
• https://github.com/jp9000/obs-studio/releases/tag/0.14.1
• https://github.com/voc/voctomix - CCC
• https://github.com/timvideos/gst-switch
• https://github.com/timvideos
• https://vasil.ludost.net/blog/?p=3247 - a way to make ffmpeg into a software mixer (in Bulgarian)
• ffmpeg has a couple ways of drawing graphs from audio analysis filters, see the examples on the 'drawgraph' filter and the ebur128's "video" option." examples:

ffplay -f lavfi -i "amovie=audio.ogg,ebur128=video=1:meter=18 [out0][out1]"