DVDShrink in two steps for transcode ?
hy all!
using dvdshrink, how can i transcode a "main movie" that need 53% of automatic compression but after my tests i saw that using 2 steps give better result. the doubt is: if the main movie have 7,976 Mb with audio 475 Mb(include) how can i divide in 2 steps with the same proportional compression in each step, if the audio never change his size? :? seems simple but i "crash" my brain searching the solution. i'm using the intuition, not a perfect way to find equal porcentage for each step. was posted in the end of that page,nobody can find a "magical" formula to do that: http://forum.digitaldigest.com/show...5&pagenumber=2 any idea to help? thanks! :wink: 
Can you explain what you mean by 2 steps ?

of course :lol: ....means:
7976Mb source to 4464Mb target using dvdshrink twice. and not using a single pass (as i call) with 53% of compression to get the target! 2 trancodes using round 26,5% and not a single pass 53%! but as you can see 26,5% seems a perfect division but it's not cos the audio don't change his size, no matter how many times you load and trancode the main movie, only the video is transcoded! this is my doubt Phil. thanks :wink: 
I do'nt really understand why you want to do 2 equal steps. Do the first one to 30% and let DVDShrink compute automatically how much will be the second step. The result won't be so different.
Note: you hould really use DVDRB when you need such compression level ! 
2 points o view Phil.
the main movie of the musical Camel have bad image quality and don't deserve to use encoders and the dvd don't have menus...or better, the worse menu that i saw.....only one ac32ch audio ....then, don't deserve a good job.....! i know that shrink will compute the sencond pass, indiferent of the porcentage in the first pass choosed. but what i read (and can't find now but i will and post here)is that with more than 30% of compression shring don't compress only the B frames(i uncertain) and after tests i saw that is better do 2 longs trancodes than only one with hard compression. but this is not the real solution. i need and want to know how to calculate that 2 passes in equal percentage if the program don't change the audio size ....example: Camel loaded in DVDShrink show: in DVD Browse, Title 1 > 02:21.12 > 7,976 Mb in Compression Settings, > Automatic 53% > AC32ch 475MB in DVD Complilation, Title 1 > 02:21.12 > 4,463 Mb than we can think: "to do in 2 steps we only divide the percentage for 2" wrong cos 1/2 of 53% is 26.5%....applying to the tanscoder i got: the first step using 26,5% in the source with 7,976 Mb give 5,862Mb but shrink show as 71,7% cos the audio don't will change the size before that first step. if i follow that way the next step will get differetn porcentage(of course) but in the final the audio will stay with the original size of the source...485Mb! this is the point Phil, i really wanto to know the way to calculate it and not only to use it! it's my will....how i can do this calculations?!?!? :? i'm feeling stup to see the problem but i can't find the solution. it's for my personal taste. the real numbers to use are source 7,976Mb with audio 475 Mb inside target 4,464 Mb with the same audio without compress in 2 full trancodes in equals porcentages! :? my ignorance can't accept my own ignorance and i need to know the solution! :wink: 
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I mean... you have the right to whish to have an answer to your question, but I do not see the absolute need of that :) But as you say afterwards in your post, you just want to know, so let see if we can find a solution for you ;). Quote:
When DVDShrink indicates 53% that means that the final target will be 53% of the original size. In other words the compression is 47% :!: (47 = 100  53) Then if you want to divide something by two, this is 47/2 = 23.5%. Is that what you did ? Quote:
The source size is not anymore 7976 with 475 audio, but 5862 with 475 audio. As percentages are proportional numbers, when you change the numbers, you changes the percentages ! You can try to use Excel and its solver to find this out by a stepbystep approach. 
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because musicals like Led ZEp are TOO BIG and good sound but not so good image. more than 30% of compression in each step will get more looses....i want to stay with 30% of max compression for that movies that don't deserve encodings! :wink: Quote:
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:lol: :lol: :lol: that's why i'm calling for help. seems easy at the first sign but is very complicated. Quote:
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:arrow: now i'm back to egg...... :roll: HOW I DO THAT CALCULATIONS PHIL? :lol: :lol: :lol: 
Maybe not a specialist of video compression, but my two cents may help...
Instead of dividing a global percentage by 2 to find out the value you want, I think you should remember that percentages are submitted to the laws of multiplication, not addition. Therefore, if you want to achieve a global T % reduction, you should apply twice a 10.SQR(T) % reduction. Hope this helps :) 
thank you Livlanderbut you don't know some details:
first i don't use excel or something but i need the "magical formula".....your recomendations can be cool(and are) but my first problem remains the same: how i do that formula? :? i'm not advanced in math for this reason i call for help here and in dvdshrink forum and this is the second reason: after long tests and friendly discussions the conclusion after my tests is: better is do the trancode in 2 times with short compression, than only one with big compression.....in the end everybody there agree with that point but nobody answer how to apply the formula that seems simple but is very complex for me and for all (i think) cos the answer still in the "air" ....nobody post any solution. did you saw? http://forum.digitaldigest.com/show...5&pagenumber=2 do you want to read from the start..click here cos is not so big: http://forum.digitaldigest.com/show...5&pagenumber=1 now my (repetitive) question for you and for anyone that want ot help: if you know how to do that, please, :arrow: post it here cos i really don't know how to do.... and 2 forums will thank you include me here and there! can you, please? (this is the central point my friend! ) can you do that? :wink: 
Jorel I'm thinking about your problem (hat is basically an equation of the second order to resolve). Just let me a little time ;)
Note: Nobody posted a solution because it has no real interrest ! That's only for brain pleasure ;. The real interresting thing to do is not to have the same percentage in both pass, but to have each pass that make you gain the same number of MB ! (you have to go from source 7,976Mb with audio 475 Mb inside target 4,464 Mb with the same audio without compress in two step so each step should make you gain ((7.976  450)  (4464  450)) / 2. Thisis a real "2step" process. But it means that each step wil have a different percentage. 
Okay, let's try LedZep (Although I tend to prefer Camel ;)
Necessary compression : 65.8% In two passes, apply 10*SQR(65.8) = 81.12 % each pass. Led Zep disk one loaded in DVDShrink show: in DVD Browse, Title 6 > 01:42.13 > 5,668 Mb in Compression Settings, > Automatic 65.8% > with: LPCM 2CH 1,189Mb, AC35.1 345Mb, DTS 5CH 582 Mb in DVD Complilation, Title 6 > 01:42.13 > 4,463 Mb Means that :  AudioSize = 1189 + 345 + 582 = 2216  VideoSize0 = TotalSize0  AudioSize = 3552  VideoSizeFinal = VideoSize0*65.8/100 = 2337  TotalSizeFinal = VideoSizeFinal + AudioSize = 2337 + 2216 = 4553 (small difference here compared to 4463, don't know why...). In two passes First pass :  AudioSize = 1189 + 345 + 582 = 2216  VideoSize0 = TotalSize0  AudioSize = 3552  VideoSize1 = VideoSize0*81.12/100 = 2881  TotalSize1 = VideoSize1 + AudioSize = 2881 + 2216 = 5097 Second pass  AudioSize = 1189 + 345 + 582 = 2216  VideoSize1 = TotalSize1  AudioSize = 2881  VideoSizeFinal = VideoSize1*81.12/100 = 2337  TotalSizeFinal = VideoSizeFinal + AudioSize = 2337 + 2216 = 4553 Don't know if this helps though... 
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81.12 means taht at the end of the process Video+Audio size will be 81.12% of the original (video+audio) size. It's really more tricky than you thought it was ;)) 
Not that bright a calc so :/
Back to the initial example, Quote:
Applied to [Video+Audio] does not seem to match either. 
I don't know but (5,668  1,189  582) * 65.8% + 1,189 + 582 = 4335.26
So it seems you were not so wrong 8O I will try to figure this out by doing some tests. 
Hi guys! Long time since we last spoke ;)
Please, forgive an ignorant guy, but what's the point in doing the encoding in two steps? I'm guessing the quality is supposed to better that way, but how come? Won't the video look the same with only one step? (Confused....) :roll: 
8O please boys:
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you need to restart from here cos:  AudioSize = 1189 + 345 + 582 = 2216  VideoSize0 = TotalSize0  AudioSize = > 3452  VideoSizeFinal = VideoSize0*65.8/100 = > 2271  TotalSizeFinal = VideoSizeFinal + AudioSize = 2271 + 2216 = > 4487 now kidding: small difference here compared to 4463, i know why...: Quote:
...scientistis knows everything about equations but nothing about arithmetics calculations. :hihi: that's why nobody understand cientistis :rotf: i told you...seems easy but.... :banghead: Quote:
please, read the links posted too :!: 
I also should like to do a bit contribution to the question. In fact, in math´s viewpoint we have a system with 2 degrees of freedom (percents A and B of each pass) and 1 (one) constraint (size of target); in this way we have a indeterminated system, which means that we have a relationship between A and B, e.g. B=B(A). So We´re going to model the problem in this way:
Let it to be Code:
SSa Code:
a=A/100 Code:
(1a) Code:
S´ = (S  Sa) (1  a) + Sa (1) Code:
b = B/100 Code:
S´´ = (S´  Sa) (1  b) + Sa (2) Code:
b = 1  alfa/(1  a) (3) Code:
a^2  2a + (1  alfa) = 0 
Solving the previous equation by using Bhaskara´s formula, we have the following roots:
Code:
a1 = 1 + sqrt(alfa) (1) If we remember who is alfa e back the calculation, we have that: Code:
1  alfa = (Size of Source  Size of Target)/(Size of Source  Size of Audio) Code:
a = a2 = 46,82% 
I didn't remember a second order equation was so tought to solve :) :bowdown: :bowdown:

Danilo,
my bad memory forgot :oops: that you are physics teacher and the worse, i only needed to ask you. :roll: shame on me..... :oops:( with a friend and teacher in Brasil, the help was in my own home. :bowdown: but now i need to know how to apply your formula using numbers. can you please post how simple mortals can use it? :screwy: please, don't delay....my anat knees are hurting but i deserve it! :bowdown: ( :lol: ) thanks in advance danpos! :D 
Amazing feedback, guys ! It´s a pleasure to help a friend as well as to do a "brain exercise".
@Jorel Sorry for my late feedback (I was in my work ! :oops: ). In final step of calculations I make a mistake, sorry ! :oops: I forgot of sqrt (which means "square root" ... By the way, I agree that some steps omissions in the calculation to become the result unclear. So, fixing the error, we have Code:
a% = [ 1  sqrt[(Size of Target DVD  Size of Audio DVD)/(Size of Source DVD  Size of Audio DVD)] ] x 100 a% is the percentage which will be applied in each pass from two ones. You pay attention that result is general one and depends of size of your source DVD , size of your target DVD e size of DVD audio (source). So, I get the data that you provide which were the following: Code:
Size of source DVD = 7976 MB 7976  475 = 7501 (size diference between DVD source and DVD audio) 4464  475 = 3988 (size diference between DVD target and DVD audio) So, we have to perform 3989/7501; after to extract to square root of that result and then the one is deduct from 1; finally we multiply for 100 e then we will get the percentage ! In the present case, it will be: Code:
27,08 % 
Nice set of calculations Danpos.
Actually, if you have a look at my proposal, my suggestion was to use what DVDShrink gives for a one pass compression [T] to calculate what is needed for two passes with the same compression rate [T'=10.SQR(T)], thus forgetting any calculation involving respective sizes of audio and video. The result is general as well, but is based on the estimation of DVDShrink itself. If you need two passes with different compression rates, T1 and T2, the general formula is : T1.T2 =100.T . Applied to the Camel example: Quote:
If you make it two passes with same compression, you need 10.SQR(53) = 72,8 % each time. It means that for each pass, you "eliminate" 10072,8 = 27,2%. What puzzles me is the slight difference with the result you provide [27,08]. Apparently, DVDShrink calculates think a bit differently... 
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Cheers, 
Once again:
What's the difference in quality between doing one step vs. two steps in DVD Shrink? 
hy audioslave.
like i posted for you you will only understand doing... Quote:
like i wrote here too... Quote:
:wink: 
:oops:
Sorry jorel, I totally missed your earlier answer... 
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