This unit plays audio files as follows:

CAUTION
Do not use an audio file extension on files other than audio files. In addition, do not change the audio file extension. Otherwise, the unit will not recognize the file correctly resulting in noise or a malfunction.
NOTE
MP3/WMA/AAC/OGG files written under specifications other than the indicated specification may not play normally or files/folder names may not display correctly.
Operating Tips for OGG
Audio SetMazda 6 Owners Manual: No.8 no cool air
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while performing the inspection to discover
whether poor contact points are the cause of any intermittent malfunctions.
If there is a problem, check to make sure connectors, terminals ...
Mazda 6 Owners Manual: Supplier identification procedure
Note
When asking the supplier (service center) for repair or
replacement, verify which supplier the module belongs to and enter in the
Audio Repair Order Form.
Identification With Printed Numbers/Label
1. Remove the audio unit.
2. Verify the supplier name written on the label attached ...