BIOS: Technology Means Business

The DivX 6.1 video codec is finally here. It sports a ton of new features and enhancements, perhaps the most impressive being a massive improvement in encoding speed.

According to the company’s benchmarks, even a modest single CPU will run anywhere from 14 to 80 per cent faster than the 6.0 codec depending on the quality mode selected. At the same time, brand new support for HT, SMP, Dual Core, and Dual Core + HT CPUs allows for gains of up to 300 per cent.

DivX is a digital video compression format based on the MPEG-4 technology. DivX files can be downloaded over high-speed lines in a relatively short time without sacrificing the quality of the digital video. It's often used to exchange video files.

The encoder now includes full support for single CPU, HyperThreaded (HT), dual CPU (SMP) and dual core processors. Encoding performance is vastly improved on systems with multiple logical processors and even on those with only a single CPU.
The decoder now supports multithreading for improved playback performance on all HT, SMP and dual core processors. To enable it you need to use the Decoder Configuration Utility (which you’ll find in the ‘DivX’ group on your Start menu) to ensure ‘Reduce CPU spikes using one frame delay’ is enabled and some level of post-processing is set.

The performance of Extreme quality and Insane quality modes has been improved - you can now get production quality video in even less time, and a new High-performance mode has been created which benches anywhere from 90 per cent to 160 percent faster than Balanced mode in the 6.0 codec depending on CPU type. This mode yields slightly lower compression but promises good quality and is suited to live-capture applications and other rapid encoding applications.

Fastest mode has also been improved, with virtually zero performance impact. In the DivX 5.x and DivX 6.0 codecs Fastest mode used no motion estimation and was therefore capable of producing very high quality video but with very low compression.

That meant that it was possible to use this mode for live capture on slower computers but with two major drawbacks: file sizes were huge and the output could not be played immediately on DivX Certified devices - you had to re-encode it in one of the other encoding modes first. In the 6.1 codec, compression for this mode has improved so much that it's possible to encode directly into DivX Certified profiles with small, good quality files.

You can now specify a target quantiser instead of an average bitrate during encoding, enabling you to avoid multipass encoding altogether in certain circumstances, reducing encoding time by half. This new method even works with DivX encoding profiles. More optimisations for processors supporting SSE2 extensions have been added, DivX High Definition profile now allows up to 6Mbit/s average bitrate for crystal-clear HD video, and the new Lanczos resize filter is included in the encoder, enabling sharp resizing during export from any video suite.

Quarter-pixel motion estimation has been enhanced for performance, and is now available in all modes from Balanced through Insane when Unconstrained Profile is selected. The Feedback Window now displays VBV level and has variable axis for PSNR plots, making it easy to monitor encodes with very high PSNR metric results, and the Feedback Window now contains controls for changing VBV bitrate, performance mode, and psychovisual enhancement in real time during encoding. Finally, MPEG quantisation has been improved, and Brightness, Contrast, and Saturations controls now operate correctly in the DivX Decoder for DirectShow.

The free codec can be downloaded here.

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