1Current media-source stats are not supported on firefox when get use PeerConnection.getStats() API Some of the important stats that are missing are framesPerSecond which is required if we want to monitor if frames are being captured.
You talk about Firefox but this is a bug tracker for WebKit. framesPerSecond is supported in WebKit AFAIK, can you be more specific?
FramesPerSecond stat is a webrtc stats which is available through PeerConnection.getStats() from media-source stats and also outbout-rtp stats. But, on firefox this stat is not available! For more details about which stats are available we can see here: Https://webrtc-stats.callstats.io/verify/
We are tracking WebKit issues here. Please open a ticket at https://bugzilla.mozilla.org/index.cgi.