Until recently I used a utility called iFlicks to take videos for films and TV shows, populate the media information (Name, Year of release, blurb about the film or episode) and remux it into the M4V format I wanted.
iFlicks stopped working this weekend (despite me paying a subscription), and support has never been great. 4 days after I sent an email telling them that it wasn’t working I cast around and found FlicksForge https://flicksforge.com.
It’s a new Tool which has very much references iFlicks, but it seems to do a great job. It’s currently free with a caveat that it will be a subscription in future.
I thought I’d mention it in case someone else was having the same problem.