CCE SP 2.67 Advanced Settings (VBR Bias, Quality Precision)

[seven_deuce offsuit]

I've been reading a lot of forums about these things but I don't think I'm getting any clear answers. Based on my understanding about each setting is it correct for me to assume that these rules apply for the following situations:

VBR Bias

The lower the bitrate the lower the bias? By lowering the bias, it'll help distribute bits from less demanding areas to highly demanding areas. Or more simply, a bias of 20 or less for bitrates less than 3000, about 20-25 for average bitrates of 3000-4500, and a 25-30 bias for higher bitrates of 5000 and up. Although I've read posts that suggest a higher bias of about 25 for lower bitrates but I don't see how this works.

Quality Precision

I've read that with bitrates of 3000 or more, this can be set to about 28-34 and this seems to hold true for all things I've done. And for lower bitrates, a quality precision of about 20-24.

So far a VBR Bias of 15 and Quality Precision of 28 with a multipass of 4 (1+3) has looked great for all movies I've encoded. Despite what my eyes perceive, however, all I want is assurance that these general rules apply for those certain situations and that I'm understanding the settings correctly. I know this type of thread may seem redundant, but I just need some clarification.

[seven_deuce offsuit]

I'm not trying to look for the 'best' or the 'optimal' values for the settings as I know each movie differs from one to another. There's no one best setting, not one that fits everything. All I want to know is if my understanding of it is correct. An encode may look good in my eyes but really bothers me is the fact that maybe I could've done better had I fully grasped the concept of VBR Bias and Quality Precision.

[aedipuss]

as far as the bias goes, if the bitrate is under 3000 there just aren't enough bits to redistribute no matter how low you go. there comes a point of deminishing returns. the lower you set the bias the more passes cce needs to move the bits around. i've gone as many as 9+1 passes on marginal material. on normal dv to mpeg-2, set it in the middle and don't worry about it and 3+1 is fine for passes. same with QP if you have decent source video it just won't matter as long as it's not set at the fringe.

[seven_deuce offsuit]

So I guess it's the other way around: the lower the bitrate, the higher the bias? The only problems I've had encoding were with movies that last around 3 hours or more. I'm thinking of splitting most of them but for some I want to keep in one DVDR. These movies run under 3000 and without not enough bits to throw around, should I try for a more CBR finish? Perhaps a bias of 25-30 or more?

And what about high bitrate movies? Since there are more bits to redistributed, would I be right to say that a lower bias (15-20) would make a better encode verses a higher bias (25-30)?