digitalFAQ.com Forums [Archives]

digitalFAQ.com Forums [Archives] (http://www.digitalfaq.com/archives/)
-   Video Encoding and Conversion (http://www.digitalfaq.com/archives/encode/)
-   -   DVDShrink in two steps for transcode ? (http://www.digitalfaq.com/archives/encode/12742-dvdshrink-two-steps.html)

danpos 10-29-2004 07:55 PM

Amazing feedback, guys ! Its 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

Size of target DVD = 4464 MB

 Size of audio DVD = 475 MB

So, we have to perform:

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 %

Livlander 10-31-2004 05:01 AM

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:

Camel loaded in DVDShrink show:
in DVD Browse, Title 1 --> 02:21.12 --> 7,976 Mb
in Compression Settings, --> Automatic 53% --> AC3-2ch 475MB
in DVD Complilation, Title 1 --> 02:21.12 --> 4,463 Mb
DVDShrink tells us that you need 53% compression.
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" 100-72,8 = 27,2%.

What puzzles me is the slight difference with the result you provide [27,08]. Apparently, DVDShrink calculates think a bit differently...

danpos 11-02-2004 02:01 PM

Quote:

Originally Posted by Livlander
Nice set of calculations Danpos.

Thanks for so handsome feedback ! :D

Quote:

Originally Posted by Livlander
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 .

Its a great insight, Livlander ! :wink: Im remembering from my probability classes e now it looks so obvious. I liked so much of your derivative result ...

Quote:

Originally Posted by Livlander
Applied to the Camel example:
Camel loaded in DVDShrink show:
in DVD Browse, Title 1 --> 02:21.12 --> 7,976 Mb
in Compression Settings, --> Automatic 53% --> AC3-2ch 475MB
in DVD Complilation, Title 1 --> 02:21.12 --> 4,463 Mb
DVDShrink tells us that you need 53% compression.
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" 100-72,8 = 27,2%.

Exactly !

Quote:

Originally Posted by Livlander
What puzzles me is the slight difference with the result you provide [27,08]. Apparently, DVDShrink calculates think a bit differently...

I think that the differences results from rounds in middle calculations ...

Cheers,

audioslave 11-02-2004 04:41 PM

Once again:
What's the difference in quality between doing one step vs. two steps in DVD Shrink?

jorel 11-03-2004 05:39 AM

hy audioslave.
like i posted for you you will only understand doing...
Quote:

Originally Posted by jorel
Quote:

Originally Posted by audioslave
(Confused....) :roll: ...Please, forgive an ignorant guy, but what's the point in doing the encoding in two steps?

seems that you don't read the whole thread...
please, read the links posted too :!:

exact what i posted cos i "discover" the reason that 2 short compressions give better results that only 1 big compression. like you know about my horrible english, i send my answer for you again...is the same answer as before,read the link to understand! :wink:

like i wrote here too...
Quote:

Originally Posted by jorel
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.

i have the same recomendation audioslave, please read the whole thread and the links that i posted.
:wink:

audioslave 11-06-2004 08:56 AM

:oops:
Sorry jorel, I totally missed your earlier answer...


All times are GMT -5. The time now is 04:10 AM  —  vBulletin Jelsoft Enterprises Ltd

Site design, images and content © 2002-2022 The Digital FAQ, www.digitalFAQ.com
Forum Software by vBulletin · Copyright © 2022 Jelsoft Enterprises Ltd.