GPAC is mainly used to package multimedia content for local or streaming 
playback.  GPAC includes MP4Box utility which lets packaging of 
various audio and video codecs into mp4 container

Dependencies:
REQUIRED: ffmpeg xvidcore faad2 a52dec
OPTIONAL: wxGTK

wxGTK is disabled by default, can be turned on by running
WX_SUPPORT=yes ./gpac.SlackBuild