Best way to modify video frames?

[shaneneuerburg]

I'm currently working on a project that requires video calls to be recorded with a timestamp on the video, reflecting the time on the current device (rather than the server which handles the recording).

What is the best way to modify each buffer frame without hacking idoubs itself? I'm currently hacking iOSVideoProducer.mm in the following method to accomplish it:
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection

I've thought about trying to swizzle that method, as well as creating a new delegate for the video producer class to expose each buffer frame. I don't love either option.

Any suggestions?