Calculate shrink factor for DVD 4.7

Message

Joseph_sys · Post by **Joseph_sys** » Mon Dec 11, 2006 3:31 am

Does anybody have a good formula to calculate shrink factor for DVD's 4.7?

I know the capacity of the DVD is about 4.38 but the formula I have:
requant_factor = (video_size / (4700000000 - audio_size)) * 1.04

does not seems to be correct. When I used it I got 3.6Gb on a dvd that suppose to be about 4.38

erik258 · Post by **erik258** » Mon Dec 11, 2006 5:34 pm

perhaps you messed something up?

that equation tells you how small the video has to be so that video 104% the size (a margin of error i guess) will fit on the DVD. so i don't see how... unles tcrequant is not doing a very good job ...

Joseph_sys · Post by **Joseph_sys** » Tue Dec 12, 2006 1:01 am

erik258 wrote:perhaps you messed something up?

that equation tells you how small the video has to be so that video 104% the size (a margin of error i guess) will fit on the DVD. so i don't see how... unles tcrequant is not doing a very good job ...

I don't know if my calculations are correct but check for yourself (the formula above was taken from this topic):
http://forums.gentoo.org/viewtopic-t-24 ... pping.html

Maybe I've missed something in calculation, so here are the numbers:
video size: 5368709120 - movie.vob
304315676 Dec 10 15:00 movie.ac3
4357256898 Dec 10 14:58 movie.m2v

So according to the above formula:
(5368709120/(4700000000-304315676))*1.04 = 1.27
So factor 1.27 gives me: 3430588898 shrinked.m2v
now m2v + ac3 = 3817709568 (about 3.81Gb not even close to 4.38Gb available space on DVD

But if I use formula:
((5368709120-304315676)/4380000000)/1.04 = 1.11
So Factor 1.11 gives me: 3925131708 shrinked.m2v
and m2v + ac3 = 4317956096 (about 4.31Gb as close as I can get to 4.38 capacity of a DVD)

I have to make some more movies to test this formula. If I made a mistake the above calculations please correct me

erik258 · Post by **erik258** » Tue Dec 12, 2006 3:24 am

you have already extracted the video from your .vob file.

the .vob file is now useless, you can delete it. acutally, you may want to keep it around for some purpose. but for the requantize-redvdize-growisofs process you won't need the original.vob anymore.

here's my calculations in bc:
4357256898 + 304315676
4661572574
4700000000-4661572574
38427426
scale=10;38427426/1024/1024
36.6472492218
according to my numbers, if you continue with the .ac3 and .m2v you have right now, now only will it barely fit, you'll still have 36.6 megabytes free! in fact ...
38427426/4357256898
.0088191784
you could make it .88% larger! (don't actually do that, for the love of reason)

so i don't think you have to requantize at all.