I had a cover file with a .jpg extension. For some reason, it really was a BMP file - the first two bytes were 'BM'. mp3tag displays this file without problem, so it doesn't care much about the file extension, but it does use the file extension to determine mime type. This causes problems in mp3 players that rely on the mime type to display the image, for example WinAmp can't display a bitmap file if it has a image/jpg mime type.
Steps to reproduce:
- Take a .bmp file
- Change extension to .jpg
- Set it as cover for an .mp3 file
- Observe that mp3tag displays cover without problem
- Observe that winamp can't display cover
I don't know what would be good to do here; maybe just display an error dialog that something is wrong, then the user can convert the open and save the file in an image editor.
I love mp3tag, by the way! I've been a happy user for years, and in fact still am