Viseron configuration and motion detection errors

[stonehencs]

Hello,
I installed viseron today and tried to set it to detect motion and to record 20sec before/after motion detection (by default it looks like 10 before, 10 after but with motion) Unfortunately I ran into errors like this or failed:

• It doesn't record 10 seconds from the end of the motion but from the start, so only 20sec videos. I tried recorder_keepalive: true but it did not do anything literally. So I mean I wanted it like this: before 20 + full motion + after 20.
• I tried to play with the Threshold value but it didn't do anything, because if I jump in front of the camera it starts, but if I just move my hand a little bit it doesn't start recording.
• How can I specify the exact stream size? Currently 2304x1296. Is just using widht and height enough?
• I tried to specify the codec but it always throws an error that there is none. I tried specifying (h265+)

My configuration so far:

ffmpeg:
  camera:
    camera_1:
      name: alma
      host: !secret camera1_ip
      port: 554
      path: /stream1
      username: !secret camera1_user
      password: !secret camera1_pswd
      fps: 25

mog2:
  motion_detector:
    cameras:
      camera_1:
        recorder_keepalive: true #I tried this but nothing new
        fps: 25
        trigger_recorder: true 

nvr:
  camera_1:

Thanks in advance for your answers!

P.S,
Is there onviff support in Viseron? If yes, how to adapt it to motion detection?