Issues with Proprietary Windows Media Formats.
The proprietary nature of these formats (asf, wma, wmv) has serious implications for users of Windows Media Story, Windows Movie Maker and Windows Media Encoder etc.
This is covered in brief in the audio clip here, but I have added more details below.
In essence, if you create a Windows Media File, you have essentially backed yourself into a corner - you can’t open it again for editing, its very hard to recompress, and it won’t play on Mac or Linux. This is because Windows owns the rights to the file format, and won’t share it openly. With other file formats, the format is more open so you can re-edit the file and re-compress it if need be. Microsoft is completely opposite. In fact, anyone who wishes to use their format has to sign a long and scary legal agreement promising not to ‘missuse’ it - i.e.: let anyone edit or recompress it. Microsoft will take legal action if anyone wants to make helpful applications that can work with Windows Media - even not-for-profit software like the very useful VirtualDub has been treatened and forced to remove support for the asf file format since Version 1.3.
The ironic thing is that many forms of Windows Media are not a very good format anyway. In the early days, the asf file format was simply a wrapper around existing file formats, with no real contribution of innovation or intellectual property, so in my opinion, did not warrant being recognised as patentable and protectable. More recently, Windows Media has improved their compression techniques, but they are still no better than other, more open alternatives. Even now, Windows Media can suffer from ‘simple’ problems such as a lack of an index, which means that you often can’t rewind or fastforward through a Windows Media Video - you have to play through continuously from start to end.
Unfortunately, most Microsoft software that creates video (like Windows Media Story, Windows Movie Maker and Windows Media Encoder etc.) almost exclusively save it as a Windows Media Format, which of course, encourages the world to revolve around Microsoft. Occassionally you can find some of their software will save out as avi, which I would reccommend, as it able to be edited and compressed. However, doing this will probably restrict you to the high quality, large file size Digital Video codec, so may have to compress it down to something smaller if you want to share it by email etc. I will create another resource on video compression in the future, but a good start is XVid (free) or QuickTime Pro ($29).
Luckily, if you are trapped in a corner with some windows media files, there are one or two programs that can convert a wmv into a more open file format, but due to Microsoft restrictions, these programs are vary rare. I reccommend Stoik Video Converter 1.0, which you can download from here (137kb). I actually reccomend the older version 1 (137kb) over version 2 (7.5mb), which is available from the Stoik site.