Also chiming in with a project I've put together in Swift

https://www.github.com/krad/morsel https://www.github.com/krad/plainview https://www.github.com/krad/pupil

morsel ingests h264 & aac and produces fragmented mp4 files & playlists. plainview reads the playlists and uses MSE in the browser to play them via the web pupil is a WIP server that reads h264 & aac over TCP and passes that data to morsel, then uploads to any s3 compatible storage (AWS, Minio, etc)

The swift stuff works on Linux, iOS, tvOS, etc

edit:

There's also a WIP project called "kubrick" https://github.com/krad/kubrick

It's a simple POP wrapper around AVFoundation that allows for building media processing pipelines.

There's an example in the project for reading video samples and passing them through a series of Metal shaders to produce fun effects.