Hardware or software?
Codecs can be implemented in hardware or software. Software-based codecs are flexible because they can easily be updated, but they can use a lot of processing power, especially for encoding. In the early days of DVD movies, few computers were powerful enough to decode the data coming off a DVD, resulting in choppy images. Back then, there was a significant market for PCI cards that decoded MPEG-2 in hardware but this has largely faded away as PCs have become more powerful. Even so, since hardware-based MPEG-2 codecs free up the CPU for other tasks, they remain useful for editing MPEG-2 footage and are common in higher-end editing systems.
High definition video also puts the performance of software-based codecs under scrutiny. Playing WMV HD files eats up a massive amount of CPU time – especially the highest resolution 1080 footage, which can't be handled by anything but bleeding-edge PCs. As a result, hardware is coming to the rescue again. NVIDIA's range of GeForce 6 (and higher) graphics cards feature Pure Video technology, incorporating hardware-based acceleration of WMV HD decoding. And ATI, it may surprise you to know, is so well versed in the handling of HD footage that it supplies a huge proportion of the HD-decoding chippery in HD-compatible TV sets and projections systems.
Most of the codecs we've talked about are thought of as being PC-based but many are starting to move off the desktop – some into personal player devices such as those in the Apple iPod and Creative Zen ranges, and others into the living room. A number of set-top DVD players can already handle DivX and XviD files, others are at home with WMA and MP3 audio and JPEG stills, and some can even play back WMV HD. A select few can handle all these types of media and more.
You might also be surprised at the wide range of dedicated media players that already exists for use with TV sets and AV systems. Some connect to a home network and relying on being fed from PCs. Others are standalone and carry media on their own hard disk drives. The support provided by living-room player hardware will continue to broaden as new codecs gain in popularity.
Where PCs still have the edge, though, is in their ability to instantly adapt to the arrival of new codecs. Downloading new player software or a plug-in for an existing player will often do the trick – and that's worth remembering if you come across media files that don't play.
Life isn't so easy with DVD players or dedicated media players, whether portable or housebound. Their capabilities can sometimes be extended with firmware updates. But, typically, if these do arrive, they turn up long after PC users have gotten used to taking advantage of the new codec.
Thoughts
We've only scratched the surface of the world of codecs and containers. Perhaps, though, we've helped lessen some of the confusion you might have felt and made it clear that when you next purchase a DVD or media player, it's important to know what codecs are supported – to ensure it will play the content you own or intend to start using.
Hopefully, we've also opened your eyes just a little to the exciting possibilities that codecs have created and promise for the future. Compression techniques continue to improve in their efficiency and subtly - to meet the demand for higher-quality audio and video coming at us over limited bandwidth or on media with relatively limited capacities. The future is bright. The future is codecs.
