Resolution autodegrades from 720p to 480p, I need this feature

I'm developing an application which will benefit from higher camera frame rate (~10 FPS), which is availble if the images I get are of 480p. However, I get 720p frames if I launch the application, and get 480p if I pause/resume it. I wanted to know how to keep the resolution lower at application start. For some reason, it also doesn't recognise any image targets in 720p, and works in 480p but with heavy jittering.

I'm using this:

Code (CSharp):

1. CameraDevice.Instance.SelectVideoMode(CameraDeviceMode.MODE_OPTIMIZE_SPEED);
2. if (!CameraDevice.Instance.SetFocusMode(FocusMode.FOCUS_MODE_CONTINUOUSAUTO))
3. {
4.     CameraDevice.Instance.SetFocusMode(FocusMode.FOCUS_MODE_TRIGGERAUTO);
5. }

Vuforia Forums link: https://developer.vuforia.com/forum/unity/resolution-autodegrades-720p-480p-i-need-feature (it's the same thing really).