I would like to add a field in the UI

[sandycloud]

Hi ,
I use your software quite often. It is very useful. Thanks a ton!
I would like to use the HEVC codec for screen capture. So for that I would like to change the GUI to add a field that indicates if recording should be done using HEVc codec.

1. Please let me know which files have the GUI code so i can make that change and try it out.
2. Please let me know which files have the call to ffmpeg so i can make changes to send appropriate params to ffmpeg invocation .

I also plan to try out AV1 codec soon.
Thanks,
Shashikant.