i've been thinking on having an ffmpeg filter object in https://ossia.io for quite some time, which would give the timeline aspect for free (and wouldn't be too hard to integrate as ffmpeg is already used for decoding A/V and we have a very very simple plug-in API which supports audio, video and GPU processing : https://celtera.github.io/avendish ). Just not a priority... but if someone is interested in contributing it I can definitely mentor.