What is VKI?

Apr 21st, 2010 by dvdxplayer 2,165 views |Comments Off

Variable Keyframe Interval. Basically that means that keyframes will not be inserted in regular intervals as in the regular DivX codecs but where they are needed. There are 2 ways of VKI: The first is that the encoder analyzes the compressed frame, compares it against the original and re-encodes the frame again as a keyframe if the quality difference is higher than a set threshold. This way of encoding is only possible with a certain special application: M4C. There’s a command line based version and a plugin for AviUtl available (the latter is described in detail in the AviUtl guide). If you set the threshold too high you’ll end up with a lot of keyframes. Then there’s the 2nd way which is basically keyframe insertion at scene changes. In order to do that the encoding program or the codec will detect when there’s a cut (as it’s called by movie makers) occur and make the first frame of the new scene a keyframe. This can be achieved by using mpeg2aviAr (part of AviRevolution 2.1), m4c or by installing the DivX VKI codec. If you use the latter you don’t have to worry about the encoder… every program that can encode to DivX will then result in files that has keyframes at scene changes. VKI, when properly used (that applies to the first way), can help you increase quality and reduce the amount of keyframes, which may lead to higher quality again because especially at lower bitrates too many keyframes will give you a worse quality.


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