[Recording] How to set the aspect ratio in the x264 codec?

[radpopl]

Tried typing -aspect 4: 3 or -aspect 1.77 in line with codec options, but it doesn't work.

 

[R1CH]

x264 options are specified in key=value format.

 

[radpopl]

I tried:
aspect=4:3

not working (still getting 5:4)