I want to use AVAssetWriter to output video files with a constant FPS (CFR) or variable bitrate (VBR). As far as I could search, I couldn't find out. How do I implement the settings?

Hello, I will use AVFoundation's AVAssetWriter and AVPlayer for H.264 and H.265 encoding and decoding in my app. It will be used commercially, so I would like to know if I need to pay any licensing fees for H.264 and H.265 encoding and decoding.