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Old 28th March 2002, 08:32   #1  |  Link
yosemite
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Gnot calculate 1.6GB, DivX5 Pro makes 1.1GB

hi,

it's strange! Gknot tells me that my video (without audio) will 1,6GB but in the end after encoding with VD it is just 1,1 GB.

Failure?
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Old 28th March 2002, 09:34   #2  |  Link
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That's nothing strange in that . There is something called compressibility of movie . Of course if you used B frame option thats extra reduction in file size. Try to set higher bitrate.

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Old 28th March 2002, 10:10   #3  |  Link
yosemite
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sure, but how can I know which bitrate I should take?

in worst case, my movie is in the end much bigger than wished...

or is there something I can say:

100 kbps (video-bitrate) more or 100MB more, too?
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Old 28th March 2002, 12:24   #4  |  Link
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i've found that setting a higher bitrate will make the codec less predictable. try increasing the resolution instead, if you're off by about 500Mb, increase resolution until the total pixels per frame goes up by 20-30%. give it a shot, it might work
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Old 28th March 2002, 15:46   #5  |  Link
theReal
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I think if you can't reach the desired size with a bitrate x, even increasing x to 10000 wouldn't help to make the final file bigger. Maximum quality was reached, so all you can do is increase the resolution, avoid any filters and use sharp bicubic resizing.
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Old 28th March 2002, 22:38   #6  |  Link
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What we need is some kind of comp check using divx5. Jonny has made a thread about this, and i too made some tests using his directions.
You can read it here : http://forum.doom9.org/showthread.php?s=&threadid=19927
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Old 29th March 2002, 00:52   #7  |  Link
dragoman
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Hi,

If you want a totally predictable encode using DivX 5 Pro, turn off b-frames. Most of the time this is what was causing your problems.

In the smaller number of cases where the max quality is reached, you are out of luck. Use ac3 audio, extra audio tracks, etc... to fill in extra space.

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Old 29th March 2002, 05:36   #8  |  Link
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Quote:
Originally posted by dragoman

If you want a totally predictable encode using DivX 5 Pro, turn off b-frames. Most of the time this is what was causing your problems.
I hope you realize that by doing what you said, he would have an encode that is bigger, and with less quality. Come on! The objective isn't to fill the CD, it's to have great quality! If the file is 1.1 GB with quantizers 2, it must have a great quality so there is no quality to be gained by disabling b-frames and filling the 1.6 GB with an encode with average quantizer maybe more than 2.
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Old 29th March 2002, 08:55   #9  |  Link
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As I understand, B-frame is compressed more then P frame (delta frame) , so B frame is for use if you want smaller file size with same bitrate . Video quality is equal in both cases (or maybe better without B-frame). Yosemite didn't say what he was using but I guess it was 2pass not 1pass-qulity .
I must agree with dragoman . Turn off B-frame ,and if that don't help try using Divx4Log prog. to edit log from 1st pass and change quantizer .

FFS

P.S. I'm not sure is B-frame simply better compressed or it's used higher quantizer ?!
Sorry , I wrote this P.S. before I saw dragoman’s post and –h’s replay about same thing.
(Sorry for my bad english , but I'm geting better )

Last edited by ffroms; 29th March 2002 at 09:45.
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Old 29th March 2002, 09:36   #10  |  Link
yosemite
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yop, I used 2pass encoding?

or is 1pass quality encoding better than that?
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Old 29th March 2002, 09:50   #11  |  Link
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1pass quality is better 'couse it don't use bitrate but fixed quantizer (compression) and all frames are compressed same. Of course there is still question about B-frame (it's compressed 2x then other frames) so I guess it's better without B frame but you can expect higher file size.

When you were doing 2pass encoding did you change mQ and MQ (by default it's 2 and 12) ? Try to set them both to 2. That way you will have fixed quantizer.

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Last edited by ffroms; 29th March 2002 at 09:59.
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Old 29th March 2002, 10:51   #12  |  Link
DJ Bobo
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I don't use the PRO version of DivX5. I use the normal version and it's 100% predictable. When you get an undersized movie, that means that it is already saturated, no matter how much you make the bitrate higher, it won't get any bigger. If you wanna a bigger size, you gotta higher the resolution.

@ffroms
setting both quantizers to 2 is equivalent to quality based 100%
IT's USELESS & TIME WASTING then to use 2-pass encoding!
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Old 29th March 2002, 11:40   #13  |  Link
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I'm new at divx so correct me if I'm wrong.
Here what I think.
Let say you set bitrate at 1000kbps and both quant at 2 (in 2pass) . This will give you file with fixed quant but codec will try to stay close to given bitrate.
If you try to do same movie with 1pass-quality and quant at 2 will give file with only compression at 2 without thinking about bitrate so you probably end with bigger file.
There is still matter with B-Frame.

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Old 29th March 2002, 11:59   #14  |  Link
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If you set both quantizers to the same setting, DivX will IGNORE the bitrate! you set 0 or 10Mbps, you'll get the same size!
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Old 29th March 2002, 12:09   #15  |  Link
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Thanks for clearing that up to me. I wasn't sure . Anyway , I'll do some testing.
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Old 29th March 2002, 14:33   #16  |  Link
dragoman
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@tripnotik

Yes, I know exactly what turning b-frames off would do, however he was asking how to get a predictable filesize. Turning off b-frames is the only way to do this in DivX 5 Pro

@ffroms

How do you know that the codec doubles the quantizer for b-frames? Where did you get this information?

@bobonts

Yes, you are correct if you want the best quality, but your filesize will be very large and you cannot predict it.

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Old 29th March 2002, 15:19   #17  |  Link
DJ Bobo
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@ dragonman
http://forum.doom9.org/showthread.php?s=&threadid=22011
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Old 29th March 2002, 15:39   #18  |  Link
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If you don't want to go undersized:

1) Use compressibility test: http://forum.doom9.org/showthread.php?s=&threadid=19927
2) If you get more that 80% you'll probably get undersized avi... so try to increase the resolution or decrease number of cds or play with bicubic methods
3) If you get 95%-100% or >100% you can go with a costant quality encoding with quantizers = 2 (without changing setting)
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Old 29th March 2002, 21:08   #19  |  Link
theReal
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Quote:
Turning off b-frames is the only way to do this in DivX 5 Pro
dragoman, this sounds like you could NEVER get the right filesize with b-frames, and that's not true. If the quality is not saturated (i.e. for most one-cd rips), you can also reach the desired filesize exactly.
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Old 30th March 2002, 05:16   #20  |  Link
dragoman
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@bob - thanks for the thread reference....just proves I am right in what I said

@theReal

You are correct sir, I should have said "only way to do this 100% of the time" - if you are using b-frames and the quality is maxed, then it doesn't work.

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