To install Curlew in ubtunu/mint, run these commands in a terminal:

sudo add-apt-repository ppa:noobslab/apps
sudo apt update
sudo apt install curlew

Or just download deb file from: SourceForge

You can download Curlew as rpm packages in Fedora from: Here

To install Curlew from source, please download zip file directly from: GitLab.

You can download ffmpeg binary (static build) from: here.