When DetermineContainer() is checking for MP3 files, it skips over the file header and checks that there are several audio frames in the file. However, it only checks the first 8K of the file, so if the file contains an image (or other large fields) in the header, no audio frames are found and the file is not detected as MP3.

This needs to be fixed to check the header for valid entries.

Header format can be found at http://id3.org/Home.