Custom audio/video filters on the fly like mpv

[jouven]

Is your feature request related to a problem? Please describe.
In vanilla mpv video/audio filters can be used on the fly e.g., video cropping can be toggled adding Shift+c vf toggle crop=960:1080:0:0 to the input.conf and the filter can be toggled during playback without reopening the video. As far as I know this feature can't be used in SMPlayer. I'm aware SMPlayer has hardcoded filters in the menus that do apply filters on the fly, but those are fixed. The only other place I know is the "options for mplayer/mpv" tab which allows custom filters per file but changing that forces a video reload, which for local media it's fast, however not on the fly, but for any kind of remote/streaming media it can be slow-painful.

Describe the solution you'd like
I imagine this can be done in different ways, like adding a custom filters menu where the user can add those, globally o per file, however being able to use key shortcuts would be the ideal option.
This probably delves into allowing the user to customize what's send to mpv, which probably allows even more customization than video/audio filters.