Looks good. Good work on shipping! I love seeing video applications utilizing Web Assembly. However, it usually falls short in when it comes to longer video in the browser's sandboxed environment.

How is the performance? Curious if you've tried using the FFmpeg libraries directly (libav), rather than compiling all of FFMpeg to WASM?

I always end up using running FFmpeg directly since it's faster and more reliable, but I still have some hope for a full functioning browser-based implementation someday.

I also made https://ffmpeg-commander.com a while back to generate commands for FFmpeg.