DVD-RB free with OPV, HC Enc and you

[techreactor]

I doubt that a CQ factor change measured in hundredths is making much of a difference... I also believe that the only way to get consistent accuracy above 99% is through two passes or the equivalent amount of time in predictive passes. But -- we're all entitled to our opinions.

I have used GetCQ and have seen its predicted sizes, with a small sample size it uses (I use 6%) and few decimals up/down can result in few MB of difference from the desired size, so the multiplier effect on the DVD5 size can bring about big differences in MB's.

Although I agree with you that for consistent accuracy, one should always use 2 pass, but the motive of OPV is to save on time, compromising the quality and size factor.

[jdobbs]

The problem is in the diminishing returns. For example, if you use a 6% predictive sample and it takes 5 passes to find a reasonable value -- then you've already used up 30% of the time it would have taken to do the the first pass of a two pass encode -- and your result will still be off by up to 5% (in either direction). Then -- if you have to do the second pass anyway (to reduce it for the half of the time when it goes over) you will be taking 130% of the time it would have taken for a two pass encode.

So in order to ensure the time is always truly saved -- you have to predict with prejudice for the low side -- which is what DVD-RB does. As a result you'll rarely go over, and usually see sizes between 4.19GB and 4.36GB.

[correction] I meant to say 4.36GB in the last sentence -- but typed 4.46...

[techreactor]

The problem is in the diminishing returns. For example, if you use a 6% predictive sample and it takes 5 passes to find a reasonable value -- then you've already used up 30% of the time it would have taken to do the the first pass of a two pass encode -- and your result will still be off by up to 5% (in either direction). Then -- if you have to do the second pass anyway (to reduce it for the half of the time when it goes over) you will be taking 130% of the time it would have taken for a two pass encode.

So in order to ensure the time is always truly saved -- you have to predict with prejudice for the low side -- which is what DVD-RB does. As a result you'll rarely go over, and usually see sizes between 4.19GB and 4.46GB.

Yeah! I understand that, but in my experience with GetCQ you will get to the CQ value in 3-4 attempts, each attempt takes 10-12 min (on my PC), so even if we assume 3 passes, 3 x 12 = 36 min for getting the CQ value. So even then a person can save UPTO 2 hrs overall (depends on movie length also). And if the avg BR are high, you can hardly make out the difference between the Normal quality mode and OPV mode of DVD-RB.

but yes, the risk of going overboard(in terms of size) is always there, for which the trick is to still some extras menu's w/o audio.

Although it would be interesting to see how OPV behaves, if you dont round of the CQ values and keep the prediction value in 3 decimals.(i.e. if you decide to implement it, eventually)