KB21: Error message "The audio file has an invalid format"


When burning an audio CD with CDBurnerXP and adding one or more MP3 files, a dialog is shown which says that “the audio file has an invalid format”.


Because of patent issues, CDBurnerXP does not include its own MP3 decoder (required to read MP3 files). Instead, the MP3 decoder that ships with the Microsoft Windows operating system is used. Under some circumstances, this does not appear to work, which results in the error stated above.


You can manually replace a file in the CDBurnerXP application directory, in order to extend its MP3 capabilities.

  1. Open the CBurnerXP application directory (typically located at C:\Program files\CDBurnerXP).
  2. Check the properties of the file “bass.dll” (right click on the file and click “Properties”).
  3. Under “Details” the version of the file should be shown (example:
  4. Download the corresponding BASS program library, and replace the bass.dll in the application directory with the bass.dll contained in the downloaded ZIP file. For version 2.3.x (older versions of CDBurnerXP) download http://us.un4seen.com/files/bass23.zip, for 2.4.x download http://us.un4seen.com/files/bass24.zip.

For more details on BASS, see http://www.un4seen.com/