[FFmpeg-user] how to set VideoBitrate for ffserver

[Soho Soho123]

> Depends on the video codec. Generally speaking, you should use a
> quality-based (VBR) approach, rather than setting a bit rate.

What is VBR approach?
in my application currently:
format :mjpeg
video codec :mjpeg
then how about the video setting in ffserver.conf?

below is mime currently:

<Stream test.mjpeg>
Feed feed1.ffm
Format mjpeg
VideoSize 640x480
VideoFrameRate 30
VideoBitRate 256
VideoQMin 1
VideoQMax 10
Noaudio
</Stream>
is anything un-reasonable?