I'm trying to mux a 1080p video I got from youtube to my own audio file (wav).
However when I load the MP4 video into mkvmerge, I get the error "The input file xxx.mp4 does not contain any tracks".
Presumably it cannot read the video only file for some reason. This appears to be a known issue and has yet to be fixed.
Are there any other tools which can achieve the same thing?