That's correct! And that's the legal option you've got.
You'd need a custom set of these files:
- avcodec-voukoderpro-61.dll
- avdevice-voukoderpro-61.dll
- avfilter-voukoderpro-10.dll
- avformat-voukoderpro-61.dll
- avutil-voukoderpro-59.dll
- swresample-voukoderpro-5.dll
- swscale-voukoderpro-8.dll
Take a look at https://github.com/VoukoderPro/FFmpeg to get an idea on how to do it.