RoBa multipass VBR and Bitrate TAB

[Holomatrix]

Hi, just wondering why, when you select the RoBa multipass VBR in the encoder tab the bitrate setting under the birate tab disapear? Is it because using this method, there is no telling how many CD's you are going to get?
Thanks

[UltimateDBZ]

That is a bit curious.. apparently your theory is correct. But if it is, then there's downside #1 to the roba method...

[Holomatrix]

I have been wondering about this for a while, just thought it was a cosmetic 'glitch' and stuck to using the previous version until the new version was fully released, but has been a while now so tried it again yesterday thinking that if I set the amount of CD's I want first then checking on the RoBa multipass method then my settings would still be there but just could not see them because of the 'glitch'. (set for 1 cd got 2 and a bit) so did not work. I will try to set the Max. Ave to 1 CD using bitrate calc and see what I get tomorrow.

[UltimateDBZ]

Such a thing is unlikely to be a glitch, as the visible property of all the controls that disappear must be set to false, and the chances of such a thing happening by accident are near-zero. So it was done for a reason, I'm waiting to see just what that reason is :)

[Holomatrix]

True. I was just doing some thinking and I'm probably going to answer my own post here but I think the reason why you cannot determine the final out put size is because the method is based on constant quality encoding, so if you select a higher Qfactor then the file size is going to be bigger. So the bitrate DVD2SVCD chooses will be based on the Quality output you tell it to encode at, so telling DVD2SVCD how many CD's you want and then turn around and tell him to give me this type of Quality, is totally redundant, two different entities here.

[Holomatrix]

almost forgot, but what do you need to set the passes at? 1 or 2?
Thanks

[dvd2svcd]

Because of the way that DVD2SVCD works, the size (and consequently the average bitrate) of a SVCD depends only of the movie time length, without taking into account its compressibility. Since the author recommends that the average bitrate should be always between 1600 and 2230, the majority of the conversions done with DVD2SVCD have good quality. I say the majority, but not all. There is the possibility of, for example, producing 3 CDs of a film of 140 minutes of easy compressibility in 2 CDs, wasting then 1 CD. It could happen also that we use only 2 CDs for a film of 110 minutes when, in the truth, its compressibility is hard and would need 3 CDs.

I think that you have misunderstood the idea behind the RoBa method. The idea is not to control the number of CDs used but to maintain a minimum quality in all the movies you make with RoBa (using the same settings between each encode naturally). So you see in that respect dvd2svcd will just use the number of CDs needed. So it is not an error, it is fully intentional and imho it is not a downside but an upside because it is one less concern for the user.

[Holomatrix]

So would the previous statement above;

Originally posted by Holomatrix
reason why you cannot determine the final out put size is because the method is based on constant quality encoding, so if you select a higher Qfactor then the file size is going to be bigger. So the bitrate DVD2SVCD chooses will be based on the Quality output you tell it to encode at

be correct?

or should it read - "do to Quality based control by the user, the number of CD's spanned, will be based on the quality chosen" ?

[dvd2svcd]

IMHO you're saying the same as what you have quoted, but perhaps yours is a bit clearer.

[Holomatrix]

Originally posted by dvd2svcd


I think that you have misunderstood the idea behind the RoBa method.

so would you retract this previous statement that came after my "I think I answered my own post" statement? or am I still missing something? :)

[dvd2svcd]

Well, you wouldn't have asked about the bitrate tab if you had understood the idea behind RoBa. So what's your point?


Edit:

I see now what your point is. I had only read the two first posts when I jumped to the gun. I see you have answered your own question in the posts further down. Sorry.

[Holomatrix]

/np :)