Why am I experiencing low frame rates when using multiple QTCaptureVideoPreviewOutputs with a single QTCaptureSession?

Question

I have an app in which the same captured video is displayed in multiple QTCaptureLayers. I am experiencing very low frame rates. Why is this happening?

Answer 1

The problem in my case was that I was neglecting to synchronize the pixel buffer attributes across the different QTCaptureVideoPreviewOutputs. The input had to be processed for each of the different settings of pixel buffer attributes, which resulted in decreased frame rates.