Q re determining 1st Pass AVI size

[JimmyBarnes]

One does this essentially by doing a 1-pass 100 % quality run with quantiser set to 2.

My question is: Should any of the MPEG4 Tools boxes be checked, if one is using them for the 2-pass, 2nd pass run? I normally use GMC and bidirectional encoding.

It seems Bidirectional Encoding should not be checked in any case, but I've been told that GMC both should and should not be checked by two different people.

Which is correct? In partic I'd like to hear from ppl who routinely determine 1st pass size so they can check their 1st Pass %.

thanx
JB

[Acaila]

Everything that affects 2nd pass should also be done for 1st pass. How many times has that been said before?
Whether or not GMC actually affects the size is disputable, but to be on the safe side just check it.

[JimmyBarnes]

Originally posted by Acaila
Everything that affects 2nd pass should also be done for 1st pass. How many times has that been said before?


Yes that's true for 2-pass, 1st pass and 2-pass, 2nd pass.

But I'm talking about 1-pass 100 % quality. I'm trying to find the maximum size to which the movie can be converted, for a given resolution, using quantiser 2.

Then I can reference the size of the actual run (using quantisers 2 thru 8 say) to this "1st Pass size". In DivX3.11a terms this was the GKnot "1st Pass %", where 60-75 % was deemed necessary for a quality rip.

Anyway, I'll try it both with and without GMC (no MPEG4 Tools) and see what the sizes come out to be. By definition, the 1st Pass Size must be the biggest AVI size possible.

JB

[jonny]

Why don't you look at the tests on my site?
I think this can help you

http://jonny.leffe.dnsalias.com/whywork.htm

GMC and QPel have only a little influence... the only good new option is BFRAMES i think

[JimmyBarnes]

Originally posted by JimmyBarnes
Anyway, I'll try it both with and without GMC (no MPEG4 Tools) and see what the sizes come out to be. By definition, the 1st Pass Size must be the biggest AVI size possible.

JB

1-pass 100 % quality (quant=2) AVI filesize results for Dogma (PAL DVD):

With no MPEG-4 Tools: 1198.13 MB
With GMC the only MPEG-4 Tool: 1191.78 MB

I guess no MPEG-4 Tools has it.

A mere 0.5 % difference for this DVD, but for some DVDs it might be more.

The above used DivX Pro 5.0.1, VDub 1.4.10 and the avs file produced by GKnot 0.23b (AVISynth beta 37)

JB

[jonny]

I've obtained the same result, even QPel perform better than GMC in size reduction!!!

[dragoman]

Hi,

jonny, a question: How did you predict the filesize for a 100% quality encode? I thought this was not able to be determined until after encoding was finished in that mode....

Just curious :)

dragoman

[jonny]

I basically read the log file for the first pass, this contains the info needed... and with some calculations you can predict the size for the full frame encode.
Note that KGnot do the same thing with DivX4, it only don't show you the predicted sized... but the comptest value is derived from the predicted size.