How to boost Keyframe in 1 Pass Mode?

[bobby8798]

hi

how can i boost the keyframe/i-frame in 1 pass mode?

the feature is greyed out, and is only active under 2-pass tuning


i'm trying to find an equivalent to nandub where u can boost the keyframe in 1 pass mode

thanks

[Didée]

No way to do that in a "percentage way".

If you know in which region your final quantizers will fall, you can restrict the I-frame quantizers on the "quantization" tab. (restrict them to 2-2, and you have the ultimate boost ;) )

[bobby8798]

Didée,

that is way too complicated

there must be an easier way

thanks anyway

[Didée]

Another way would be to use "mpeg custom" quantization, and lower all the values in the left quantization table. That works your request out - but this would also touch P-frames, though (the kblocks in P-frames).

But still, I do not see any need for boosting I-frames! The way they come out-of-the-box is nicely balanced to overall quality, I think.

Didée

[bobby8798]

Didée

i don't want to touch any of the quantizations

i find boosting i-frames is extremely important, especially for scenes with some black in them.

i'll stick to nandub for now

thanks for the help

[sam_b]

If you're familiar with nandub, how is restricting the quantisers too complicated??

Divx3 tends to leave large area's of the keyframe intact (with static noise), making the key-frame more important. XviD does not tend to do this, and so there is much less dependance on the keyframes. Have you actually found a need to fix the keyframes in XviD, or are you assuming it will be needed?

[bobby8798]

sam_b

limiting the i-frame quantization does not have a 1-1 correlation with boosting the i-frame by 50% or 100%. you don't know Exactly what the quantization should be for each and every i-frame.


I'm doing a comparison test against XviD. When comparing keyframes, that are boosted, against the XviD keyframes, the XviD keyframes are inferior.

Overall video quality test: XviD is sometimes better, and sometimes worse.

Boosting the Keyframe becomes very important when the keyframe rate is reduced to 1 sec !!