Convert aac to xvid

What is the difference between .aac and .xvid?

Developer: Bell Labs, Fraunhofer Institute, Dolby Labs, Sony and Nokia; Xvid

Description: Compressed audio file similar to an .MP3 file, but offers several performance improvements; examples include a higher coding efficiency for both stationary and transient signals, a simpler filterbank, and better handling of frequencies above 16 kHz; maintains quality nearly indistinguishable from the original audio source.; Xvid-encoded video files are digital video files that have been compressed and encoded using the Xvid codec, an open-source video codec designed for compressing video data in order to facilitate faster transmission over computer networks or for more efficient storage on computer disks. Xvid, which is a reverse spelling of "DivX," emerged as a popular format due to its ability to compress video files without significant loss of quality.