dicas, the German MPEG-4 AVC/H.264 encoding specialist, has unveiled a new revolutionary quality enhancing algorithm called dicasVICO. In order to attain the same picture quality like current H.264 encoders, streams modulated with dicasVICO get by on bit rates being lower by 30 per cent. dicasVICO helps broadcasters and providers of WebTV, MobileTV and IPTV services to overcome bandwidth restrictions and dramatically enhance the picture quality of their programs.dicasVICO allows for a more efficient use of the available transport capacity by optimising the distribution of bits among the image sections of a video picture during the encoding process. Unlike most current encoders, the algorithm by dicas is not based on prevalent statistical measures but on the properties of the human visual system.
“Most H.264 encoders use variance algorithms to modulate the quantiser”, explains Klaas Schüür, co-founder and CTO at dicas. “Although you may get great measuring results by applying complex operations based on rate distortion, this does not reflect the latest state of scientific knowledge on the visual perception of man.”
dicasVICO, on the contrary, takes advantage of the gradual fault tolerance of the human visual system against varying optical phenomena. For example the human brain hardly notices errors occurring in high-frequency sections, i.e. fast movements or fine-textured patterns, whereas it is very attentive towards errors within regular structures or slow-motion sections.
To what extent a higher encoding accuracy is applied on the particular image sections is controlled by dicasVICO in accordance to the picture’s visual complexity. Such a selective quantisation may lead to lower statistical results, especially when current technical measurement standards like signal-to-noise-ratio (PSNR) are used. Mere statistical measuring methods, however, are hardly significant concerning the subjective picture quality.
Perception tests show that the visual complexity approach has an enormous impact on how a video stream is perceived by its viewers. Subjectively the stream with dicasVICO algorithm applied on appears to be much more brilliant and clearer. “Especially at low bit rates videos encoded with dicasVICO show substantially less artifacts”, says Schüür. dicasVICO is now part of all dicas encoder hardware products and mpegable software packages.
