When writing a tag with string, the library doesn't add the NULL terminator to the string if it's the last field of a frame, although all text fields are supposed to be null-terminated.
How reproducible: Write a tag (tested with USLT) and see that the string isn't null terminated in a hex-editor.
Actual results: Strings end and than there is the next frame identifier.
Expected results: There should be a null character after the string in addition to the frame length indicator.
Additional info: http://www.id3.org/id3v2.4.0-structure
I made a patch that fixes it and tested it on my machine, it's attached. (AMD64 machine)