I'm trying to use MKVMerge to convert from iTunes m4v (with DRM removed) --> MKV.
MKVMerge always says "everything went fine", but a lot of the time the videos fail during playback at some point.
Should I be using a specific version of MKVToolnix? Specific settings?
Post the details from the m4v using mediainfo.
But why remux? Most stuff that supports mkv should play mp4/m4v.