Bitrate rate control and encoder detection

[naanlizard]

It would be useful to auto detect whether a stream is VBR or CBR and what stream encoder is being used - I'm unsure how difficult it would be.

For example the API could return Encoder: x264 or Encoder: NVENC etc, for anything we can detect. I don't know if that's possible.

More practically, CBR or VBR detection would be very useful so we can recommend to our users to switch to VBR, which I think should be possible. I'm not sure how the bitrate calculation of the incoming rtmp stream is done, but perhaps simply check every so often to see if it changes significantly. If so, they're likely using VBR.