Add comment in MP4

I have a bunch of MP4-Files and need to add co开发者_运维知识库mments to them. They are very different in nature, so I can't rely on an embedded MP3-File. Is there any way to simply "tag" or add a short comment to the file?

---

I found this tool:

http://sourceforge.net/projects/atomicparsley/files/

which allows me e.g. to tag like this:

AtomicParsley test.mp4 --encodingTool "myencoder"