The latest updates of the DIVX and Quicktime codecs have turned up within a few weeks of each other. Can they really change the way we watch video on our PC's?

You wait all year for a video codec, then two come along at once. Within a few weeks of each other, DivX 6.0 and QuickTime 7.0 have arrived, each offering unique features intended to push computer video formats to a different level.

Although the new version of DivX is a much more fundamental upgrade, both codecs are heavily aimed at a format that has yet to take off in Australia - HD (high-definition) video.

DivX 6.0

The sixth incarnation of DivX heralds a coming of age. Originally a dodgy hack of Microsoft's MPEG-4 implementation with MP3 audio, DivX was rewritten from the base MPEG-4 standard a few years ago. From DivX 4.0 onwards, the codec was entirely legitimate. But version 6.0 goes well beyond DivX's roots, taking it in a more mainstream direction. Up to now, the flavours of MPEG-4 - XviD and 3ivx - have focused on the improved compression available compared with MPEG-2. But MPEG-4 has a lot more to offer than better-quality video at lower data rates.

The original specification borrowed the track-based container system from QuickTime, so MPEG-4 supports lots of other things besides audio and video. Text, sprites, textures, synthesised music and images can all be included, as well as navigation markers. But, besides the odd company logo and some third-party subtitling, little of MPEG-4's potential has been tapped.

With DivX 6.0, however, some of the more advanced features are finally being called upon. The headline news is the DivX Media Format, which adds a host of options to a DivX video file.

Chief among these are menus and chapter points, making the video file fully navigable like a DVD. Viewers will need the DivX 6.0 codec and the Player, although that's a free download. The navigation will also work in other DivX-compatible players such as Windows Media Player, but a navigation tool will be loaded along with the file. DivX, Inc. claims that certified set-top players will support these features in the near future, too.

The DivX Media Format has also added direct support for subtitles and multiple audio tracks. Subtitles were already possible with DivX, but you had to install a number of third-party utilities to get them working.

With the XSUB system, they are included inside the DivX file itself, and different languages can be chosen on the fly, as with a DVD.

Similarly, support for multiple audio tracks allows the selection of alternative language dialogue, but can also include specific mixes for different speaker setups. Finally, the DivX Media Format supports the inclusion of metadata such as author or title using the new XTAG system.

Although the main changes with DivX 6.0 are these navigational features, no new codec would be complete without grand claims about improved compression efficacy. According to the company, DivX 6.0 makes 40 per cent smaller files than 5.0. It also compares well with the competition, squeezing video over 20 per cent more than H.264 standard. Compared to Microsoft's WMV 9.0, DivX, Inc. claims a 17 per cent space saving with HD footage and 21 per cent over DVD-quality encodes.

The download options for DivX have been altered and simplified. There are now only two different ways to get DivX - the free Play Bundle, and the $US19 Create Bundle.

The Play option includes the Player and standard DivX 6.0 codec. For $US19, Create adds the Pro version of the codec and a Converter utility. This simple app lets you choose a DivX profile, then drag and drop your footage to encode to DivX as a batch.

For those who like to try before they buy, Create can be downloaded in trial format, including six months of DivX Pro usage - but there are just 15 days before the Converter times out.

DivX 6.0 Pro adds professional encoding features such as the Feedback Window, which allows frame-by-frame tweaking of settings. Psychovisual enhancements improve video quality by considering human visual processes.