Screen grabbing

I'm new to this, so not sure if this is a bug or a feature request.
I'm trying to run the following command capture the desktop screen:
`ffmpeg.run('-f', 'avfoundation', '-framerate', '5', '-i', '"1"', '~/Desktop/ffmpeg-test-electron.mkv')`

I get an error saying **Unknown input format: 'avfoundation'**.
The command works fine when run with ffmpeg directly in the command line (without the wasm build).

I understand that for this to work, ffmpeg uses it's library called `libavdevice`. Is that not part of the wasm build?