I was wondering how you got around licensing issues, looks like you require the user to install ffmpeg and imagemagic separately which at least respects the license. Just a question seeing as you are targeting Mac as one of the platforms. Did you concider using AVFoundation for some functionality on MacOS? Similar with Microsoft Media Foundation on windows? Although both of those would have less supported formats tha…
The ffmpeg docs have an straightforward list of things you have to do to link against ffmpeg and also be compliant with the license, which I found interesting: