Compatible Audio Files

• Just like the regular iPod, the iTouch is compatible with most of the popular audio file formats: MP3, M4P, MP4, M4A, AIFF, AAC, Apple Lossless and WAV. Audiobooks from Audible, AAX and AAX+ files, are also supported.
  
  

Compatible Video Files

• Most video formats compatible with iTunes are based off the MPEG-4 standard, and include M4V, MP4 and the H.264 compression standard. Apple QuickTime files (MOV) are also supported by the device.
  
  

Incompatible Formats

• Notable excluded formats include all Windows Media (WMV and WMA) files, open source formats like FLAC and OGG, and popular video formats such as AVI. As of August 2010, there are no known plans by Apple to provide compatibility with these audio and video formats.