Using Off Screen Render to save custom .mp4 on ios

ANAFI USA / ANAFI Thermal / ANAFI 4K
1

So, I have been trying to use the offscreenrender class in the GroundSdkDemo to save off a custom .mp4 using core video on iOS to apply custom filters to the video stream on the fly. Anyone have any insight into how to pull this off?
Thanks,
Josh