The Advanced Systems Format (ASF) contains Windows Media Video(WMV), many of which contain audio and video. WMV files can get support from digital rights management (DRM), preventing the creation of unauthorized copies. Therefore, companies who sell digital copies of videos and audio on the internet prefer to use the WMV format. You can use a PC or Mac to download and view WMV files. Some MPEG-4 kinds like Real Video are also competing with WMV as the most popular video format in its family. Xbox 360, Microsoft Zune, portable media players, and online video sales, are all WMV formats. Microsoft-developed codecs require compressed WMV files. The WMV codec is used to encode ASF files. With a bit rate of 1000 kbit/s, the professional Windows Media Video 9 may stream at resolutions greater than 300,000 pixels. With their HD DVD and Blu-ray compatibility, WMV files are a great fit. At lower bitrates, the differences between WMV 9 and its competitors become more obvious. Several programs can open WMV files, however, this list isn't comprehensive: VideoLAN VLC Media Player, RealPlayer, PowerDVD, Microsoft Windows Media Player and MPlayer.