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Speed Rendering With the Right Codec

Got some time to kill? Render some video. The fastest application we tested, Mediostream's NeoDVD 4 Plus, took the length of a coffee break to convert our digital video test footage into a DVD-friendly MPEG-2 file, while the slowest, Pinnacle Studio 8, took the length of a long lunch. The credit--or blame--lies with the codecs they use.

A codec--short for compressor/decompressor--does the heavy lifting behind the scenes of these applications; the applications use them to convert and compress video and audio into a format such as AVI, QuickTime, or MPEG-2. An hour of footage from a DV camcorder takes up about 13GB on your hard drive; an application using a codec can make it fit on a 4.7GB DVD and still look fabulous, but the operation takes time. "The single biggest hindrance to rendering speed is how fast the codec is," says Richard Townhill, group product manager for Adobe Premiere. "Every single time you touch every single frame of video, you're using a codec. It is a mathematically complex and time-consuming process."

Who's Cracked the Codec Code?

For premiere, Adobe licenses an MPEG-2 codec from MainConcept. We first tested Premiere with version 1.1 of the codec; the process took 54 minutes. We then updated the codec to version 1.2, which adds support for Pentium 4 optimizations and hyperthreading, plus other tweaks; the updated codec helped us shave 40 percent off the rendering time--not unusual, according to Mark Bailey, chief operating officer of MainConcept LLC. However, our test bed used an Athlon 2000+ processor, not a P4. According to the PC World Test Center, Athlon processors access most of the same optimizations that Pentiums do, and in many tests conducted by the Test Center in the past, Athlon systems have performed just as well as--and occasionally even better than--Pentium 4 systems on P4-optimized tasks.

Ligos licenses its codec to Roxio and Adaptec, among others. Pinnacle says that both Studio 8 and Expression employ an MPEG-2 codec of its own design. But because Expression was released later than Studio and uses a newer version of the codec, Expression encoded our test files in about an hour, compared to nearly an hour and a half for Studio. Pinnacle says both versions of the codec take advantage of Pentium 4 optimizations and hyperthreading; nevertheless, both performed our tests substantially slower than the average of the products we tested.

One trick that codecs use is to analyze upcoming frames and recognize similarities to previous frames. "If you know the sky is going to stay the same," explains Brandon Higa, senior marketing engineer at Canopus, "you can see that and not do anything with it." Canopus's codec works with Premiere.

The MPEG-2 codec used for DVD movie playback need not be the same as the one used for encoding. Set-top DVD players and game consoles with DVD drives have hardware-based decoders that work just like software codecs, says MainConcept's Bailey. But movies not destined for DVD--Web videos, for example--usually require that codecs for both video and audio be installed on your system.

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