exploring the WebCodecs API with mp4 files :D. right now it can only extract frames and some very basic editing (a couple image filters, ability to delete frames). you can also seek to a certain time range and gather frames from that range.
this app is currently likely most useful for only small mp4 files (e.g. with durations of a few seconds to maybe a couple minutes).
much thanks to the contributors to mp4box.js, the WebCodecs demos/API and josephrocca.
the F-22 Raptor demo used for the example_input.mp4 file came from Wingover UHD