VLC<https://en.wikipedia.org/wiki/VLC_media_player> is described as the libavcodec library from the FFmpeg project provides many of VLC's codecs, but the player mainly uses its own muxers and demuxers. Then there is MPV<https://en.wikipedia.org/wiki/Mpv_(media_player)> which is described as free and open-source media player software based on MPlayer, mplayer2 and FFmpeg. VLC seems to include a GIU. Apparently, it uses QT4 for Linux. While MPV is still primarily a command-line application and there are a number of GUI front-ends available. I notice that these days the Ubuntu Mate distro includes Celluloid<https://github.com/celluloid-player/celluloid> (formerly GNOME MPV) - for Linux - based on GTK, written in C. Its goal is to be a simple GTK-based graphical interface for MPV that meets the GNOME Human Interface Guidelines. Makes me wonder if MPV is now becoming more popular than VLC ??? cheers, Ian.