I have a .mp3 file with some metadata, among which a comment field with a value. What's strange is that the comment can be seen on Mac OS X (both in iTunes and in the Finder), but on Windows the field appears blank. Why is this happening and is there a way to show the comment on Windows too?
There are different formats for metadada. Usually in MP3 files the metadata are either in ID3v1, ID3v2, or APE format. There are three different versions of ID3, and according to wikipedia, Windows can't read the latest version:
It could be the case that your tags are in a format that your mac can read, but windows can't.
I suggest you use a metadata editor such as MP3tag (I use it, it's quite good, it can read/write/convert all ID3 versions, APE, read and write album images, etc). See what are the versions of ID3 present and try to convert it to a version that Windows can recognize.