ASF is a media container used by Microsoft Windows Media Player. It was designed for streaming audio and video files online. The container determines the structure of the data stream but not how the data should be encoded. Usually the files encoded by Microsoft developers have the .wma or .wmv extensions, other files have .asf extension. Such files generally have MIME type that allows sending files via the internet. The main feature of the ASF is the ability to stream playback, that is the ability to play a video or audio directly at the time of downloading data over the network.

This is open lossless codecs, developed under the Ogg project. Lately it’s become quite popular: many users wishing to store audio with original quality choose FLAC. This is partly in connection with the fact that codecs uses IDv1 and IDv3 tags – this allows a user to sort an audio collection according to one’s particular tastes, changing the original metadata of the tracks.