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Old 29th March 2002, 10:23   #1  |  Link
yosemite
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2pass encoding vs. 1pass quality : what is better?

hi,

I thought that stuff should get an extra thread

Here in the board I've read the following:

Quote:
1pass quality is better 'couse it don't use bitrate but fixed quantizer (compression) and all frames are compressed same.
well, can u check that?
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Old 29th March 2002, 10:45   #2  |  Link
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It's very simple:

If the size doesn't matter, go for quality based 100%, you'll get the highest quality possible.

If the size matters, go for 2-pass encoding, you'll get better overall quality as the equivalent quality based setting (I mean "quality based xx%" that gives you almost the same size). Just try to lower the max quantizer a bit, 12 is a way too much, the best values are between 6 and 8. I work with 8.
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Old 29th March 2002, 10:48   #3  |  Link
yosemite
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well, and what do u mean with "1pass when size doesnt matters" ?

with which movie-size I have to calculate, when I use 1pass quality?


and if I take the 1pass quality, is the max quantizer still important?
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Old 29th March 2002, 10:55   #4  |  Link
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You can't predict size when using 1-pass quality based!

quality based encoding fixes the quantizer as shown in the scale!
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Old 29th March 2002, 11:04   #5  |  Link
yosemite
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so, and 100% 1pass quality mode is close as u can get to DVD quality?
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Old 29th March 2002, 11:43   #6  |  Link
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Yes , but you will end up with really large file.

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Old 29th March 2002, 11:55   #7  |  Link
DJ Bobo
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Quote:
Originally posted by yosemite
so, and 100% 1pass quality mode is close as u can get to DVD quality?
Yes, but still only *near* DVD quality!

Quote:
Originally posted by fforms
but you will end up with really large file.
Not always, there are some movies and animes that are very good compressible.
Example: Arc The Lad Anime episodes.
I got the 20 minutes episodes in 576x432 @24fps encoded with quality 100% on 120 to 180MB only!
Or Coyote Ugly, the whole Movie (about 95 minutes) in 704x304 @25fps encoded with quality 100% on 1,2GB
But Dragon Ball Z Movie 5 (about 47 minutes) in 512x384 @24fps got 1,3GB.

So it depends on the movie...
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Old 29th March 2002, 11:59   #8  |  Link
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fine !

and there's no other way to find out how much ca. file-size will be in 1pass quality mode?
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Old 29th March 2002, 12:02   #9  |  Link
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Quote:
Originally posted by yosemite
and there's no other way to find out how much ca. file-size will be in 1pass quality mode?
NO WAY!
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Old 29th March 2002, 12:04   #10  |  Link
yosemite
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so, I have to do an 8 hour "test" qith 1pass quality 100% and if it isnt good, I've to take the 2pass - that will be work *gg*
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Old 29th March 2002, 15:59   #11  |  Link
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Try this: http://forum.doom9.org/showthread.php?s=&threadid=19927

If you get more than 100% you can go with costant quality encoding (and you'll end up with an undersized movie (according to the size GKnot show))
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Old 29th March 2002, 16:43   #12  |  Link
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Jonny, i have been doing some divx5 comp checks, using B-frames, and must say that my results so far agree with your findings
Maybe TheWef could use some of your work to the new Gordian Knot?
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Old 1st April 2002, 11:45   #13  |  Link
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I'll try to drop a message to TheWef to see what he think...
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