asf The .asf filename extension refers to the Microsoft owned audio and digital video container, advanced systems format. It is a container for windows media audio and windows media video but shares the same internal structure as both WMA and WMV file formats. The format was designed with the goal of increasing efficiency in distribution of audio video files across computer networks. However, it works just as well for local system playback. The asf format forms part of Microsoft's Foundation framework. The major feature of the format is its ability to add digital rights management by providing the framework for encrypting audio and video files.
3gp The 3GP file format and its associated filename extension .3gp is an audio, video, and text container developed by the 3rd generation partnership project. The target market for the 3gp file format is 3G enabled UMTS mobile phones through associated UMTS multimedia services. Though mobile devices operating on high speed networks are the intended hardware associated with playing .3gp files, many PC codec packs exist which grant compatibility for .3gp playback. The format has a basic profile in which files of this format do not reference any external media sources and support for audio, video, and text is limited to a single track.