Where can I post questions for help using Melt mlt
closing as not-a-bug
https://www.mltframework.org/support/ explains where to go. Basically, there is a very small user community and mostly only developers using melt. However, that page leads to https://stackoverflow.com/questions/tagged/mlt, which is the closest thing. Most users use it indirectly through a graphical frontend as Shotcut, Kdenlive, or Flowblade.
My answer means that the Shotcut application contains a known good build of melt, and you can simply download that app and use the melt that comes with it. Otherwise, if you are building it yourself, you can debug it yourself. Alternatively, you can try using MacPorts or Homebrew, which are open source repositories. In case you want to troubleshoot your own build, there are too many points of failure, and I do not have time to guide you through them.
Melt won't playback .mov files on OSX
Get/make a build that works correctly. For example, "/Applications/Shotcut.app/Contents/MacOS/melt" works good.
Playback DNG files which have been converted from a RAW file