The dvix format is a media file not a container like a Quicktime file is. This can make it hard to author or even convert the file because it’s only designed to be played. Another words, a quicktime file can be editing because it is a storage house contain compressed images and audio files. A Dvix format is a file that contains a image and audio together, so quicktime might not be able to understand it very well.
A newer version of Dvix has come out recently that is now a container, but if your file is being used over the internet than it might just be a normal dvix.
Also use quicktime to see if the file is using mpeg-1 layer 3 for audio. This means it is using the Microsoft mp3 standard, which wont work properly on a mac. If this is the main case I would use a program like Dvix Doctor or VLC to fix the problem. You can also use VLC to convert the file to quicktime so it will work better, I wouldn’t use quicktime to do it myself since it normal aliases the exported file.
I hope this Helps!!