In the heady early days of the Internet as a mass medium – the mid 1990s, say – one of the key acronyms was VOD: Video On Demand. The idea was that this wonderful new Information Superhighway (another phrase very much of that era) would mainly be used for downloading video content. It never happened – in part because people found using the hyperlinked Web a much richer experience, and also because the average bandwidth was simply insufficient.

But the VOD idea was not totally wrong. One of the drivers of Internet uptake among some users – the younger ones – was downloading music. The key breakthrough was the MP3 compression technology, since this allowed a complete song to be downloaded in a reasonable time even with the existing connection speeds.

MP3 is in fact a relatively old idea – a classic case of a solution in search of a problem. Although it has established itself as the de facto standard for music compression, things have moved on. For example, an updated version of MP3 called MP3Pro has been developed. A free player and encoder are available, but relatively few products support it.

Both MP3 and MP3Pro are proprietary standards. This has led to the creation of a completely free alternative, called Ogg Vorbis. Industry backing for the group behind Ogg Vorbis has come from the streaming company RealNetworks. The latter has awarded one of its Helix Community Grants to promote the format as part of its open source Helix platform.

For its own RealAudio, RealNetworks has adopted Advanced Audio Coding (AAC), part of the broader MPEG-4 standard (MP3 is a component of the MPEG-1 standard, and is strictly known as MPEG Audio Layer-3). Another strong supporter of AAC is Apple, which has chosen it for its iTunes service. AAC has been further developed (using the same techniques employed in MP3Pro) to create AACPlus.

Although MP3 is unchallenged as the first-generation music format, things are not so clear-cut for the next iteration. Rather than deploying AAC, Microsoft has developed its own, independent proprietary standard, the Windows Media Format, which covers video too.

To complicate matters further, Microsoft also supports the official industry formats for video, which are part of the umbrella MPEG-4 standard. However, Microsoft's support is typically ambiguous: “While Microsoft continues to support the MPEG-4 standardization process, it is moving forward with the development of audio and video technologies that deliver superior quality and an end-to-end streaming solution for Microsoft customers.”

There is an official MPEG-4 site with information about MPEG-4, a FAQ and a more detailed introduction. Since part of the file format is based on Apple's QuickTime, Apple is naturally a big fan of the standard for video as well as for audio, and provides some useful background resources. More generally, the Internet Streaming Media Alliance represents those companies supporting the standard (with Microsoft conspicuous by its absence).

As in so many other domains, post-MP3 video and audio standards in the commercial sector essentially come down to a choice between Microsoft and the rest. With the continuing roll-out of broadband, the bandwidth for video on demand is now in place; but until this format war is resolved, everyday VOD seems as far off now as it did ten years ago.

Glyn Moody welcomes your comments.