Default [Q] How to change default video recording resolution?

Hello,

I have Xolo a500s. I flashed a custom rom on it. The custom rom is based on 4.2.2 but it has all apps of 4.4 like camera, launcher,calender,gallery etc.

The problem I am having is that the camera app doesnt have any option to change video recording resolution. It always record video in 640x480 resolution. but in my stock rom It used to record video in 720p resolution.

I installed camera mx app from playstore and this app gives me 720p recording option. But I dont like this app. I want my default camera app to record 720p.

can I edit camera.apk file to change the video recording resolution?
or I will have to change some files of my custom rom to change the resolution?