What is a WMV file?

Files with the extension .wmv are actually ASF files that contain video data in WMV format. ASF is a media file format (or container format) developed by Microsoft. WMV is a video codec developed by Microsoft. These formats are propriatory and may be patent and licence encumbered.

Playback under Windows

The WMV files use WMV2 for the video codec and MP3 for the audio codec. MP3 support is included as standard on Windows Media Player from at least version 7 onwards. WMV2 is included as standard with Media Player 9 or newer and is an automatic download on Media Players version 7 and 8. The WMV files produced have been tested by volunteers on Windows 2000 Professional and Windows XP and played back without issue.

Playback under Linux

The OGG version of the videos is recommended for Linux users, as it should work straight away on most distros. However, it is possible to play back the WMV files under Linux if you have the codecs installed. Typically this is done by installing the w32codecs package or gstreamer plugins. These provide access to certain codecs which allow media players to playback MP3s, WMA, WMV, QuickTime and other formats. However, they are not Free Software and are not included with most distributions.

Why do you provide videos in a proprietary format?

We provide videos in this format for the convenience of Windows users who would like to play the videos back without installing additional software. We would never release a video that required proprietary software to view, so we release the videos in two formats, WMV and OGG. Linux users and those who want to avoid encumbered media formats can use the OGG version.

The WMV version seems lower quality than the OGG version. Why?

We've noticed this too and haven't got any firm answers. The OGG encoding just seems to be better. (This could be down to the encoding tools as much as the codec itself.) The OGG files are not only smaller in size but appear to be better quality for the same image size and bitrate. If you have any tips on improving the encoding of the WMV versions then please post to the MailingList. We use the ffmpeg program to encode the videos.