this works perfectly. thanks a lot

if you don't mind, would you consider make a wrapper to this command to an app that would work as a fully working front camera app?
I believe a python script that run this command and listen to camera button, and on triggered it will run another command to capture the pic as file. I think it's doable

or maybe implement it to your camera-ui2 app? though I'd prefer a separate app since I still want to preserve my stock camera app

add.
do you have any idea why capturing to file can only create a very dark image?
I've tried it with this command

and what I can see is lamps, nothing else. as if it can only capture source of lights. but original code works pretty well though (as best as a nokia's front cam can)
note. for unknown reason omx_jpegenc and dspjpegenc won't work on my device