WMV is a codec usually used for video compression in ASF format. It is possible to open WMV files both on Mac and Windows with almost any player or convert the format to another one. WMV supports DRM protection that prevent users from copying information. It is the main reason why the format is widely used by companies that sell digital video and audio online. Also the format is well-known among users because WMV files are used on popular Xbox 360 devices. Low bitrate makes such files an ideal solution for HD DVD and Blu-ray discs.

AU is a file extension for a sound file format belonging to Sun, NeXT and DEC and used in UNIX. The AU file format is also known as the Sparc-audio or u-law fomat. AU files contain three parts: the audio data and text for a header (containing 24 bytes) and an annotation block.