I'm currently in the midst of digitising my VHS cassettes with OBS Studio. I've set the Video Capture Device to 25 FPS but it still records at 1000 FPS taking up horrendous amounts of disk space. I've also set the FPS in Settings > Video.
I've also set the Video Encoder Settings in Advanced (Video) as -r 25 -b:v 2M but it still doesn't work.
$ ffmpeg -i 2018-02-27\ 12-20-54.mkv
Input #0, matroska,webm, from '2018-02-27 12-20-54.mkv':
Metadata:
ENCODER : Lavf57.83.100
Duration: 00:05:01.72, start: 0.000000, bitrate: 21528 kb/s
Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080, 1k fps, 25 tbr, 1k tbn, 50 tbc (default)
Metadata:
DURATION : 00:05:01.720000000
Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp (default)
Metadata:
title : Track1
DURATION : 00:05:01.632000000
I know I can re-encode the video and set the FPS to 25 but is there a more permanent solution to this?

I've also set the Video Encoder Settings in Advanced (Video) as -r 25 -b:v 2M but it still doesn't work.
$ ffmpeg -i 2018-02-27\ 12-20-54.mkv
Input #0, matroska,webm, from '2018-02-27 12-20-54.mkv':
Metadata:
ENCODER : Lavf57.83.100
Duration: 00:05:01.72, start: 0.000000, bitrate: 21528 kb/s
Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080, 1k fps, 25 tbr, 1k tbn, 50 tbc (default)
Metadata:
DURATION : 00:05:01.720000000
Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp (default)
Metadata:
title : Track1
DURATION : 00:05:01.632000000
I know I can re-encode the video and set the FPS to 25 but is there a more permanent solution to this?