Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > MPEG-4 ASP

Reply
 
Thread Tools Search this Thread Display Modes
Old 6th December 2001, 05:40   #1  |  Link
Ozymandis
Registered User
 
Join Date: Dec 2001
Location: NC
Posts: 7
Resizing not necessarily a good idea with Divx 4.11

Hey guys.

I've been encoding for a year or two, and I've just been lurking till now. Anyway, figured it was time I register and start posting on the forums. It's annoying to not have anyone to talk to about encoding. Ps: is there a chat channel anywhere??? irc?

Anyway, on to the topic. I encode around 10 movies a week, and through the course of a lot of experimentation, it's appeared pretty clear to me that -not- resizing results in a much clearer picture.

I realize that this was not the case with the old 3.11 codec which didn't handle low bit/pixel ratios effectively, thus necessitating resizing to prevent the codec from getting overly blocky. (by relying on a resizing filter (which does interpolation) when going full screen to insure that you have a large, smooth picture rather than a blocky larger resolution movie). The disadvantage to this old method is of course that the codec has less input video to select from to make its decisions of where and what to compress. Logically, the codec should have smoothed the backgrounds and whatnot itself in order to prevent blockiness, but it didn't, which is why I take it that we've been resizing with 3.11 (nandub).

With Divx 4.xx, though, it's been my observation that they've dealt with problem. I've encoded many movies 3-4 times, as 2 cd cropped-only, 2cd cropped/resized, 1cd cropped-only, and 2cd cropped-only. I've done this for short action movies, longer action movies, ditto for low motion movies. In all scenarios, I've observed a -distinct- improvement in the version that's not resized.

I understand that a faster CPU is needed for playback, but I think that most of us who are into divx have fast enough processors for that anyway. Another good reason to resize would be to set a perfect aspect ratio of course.

My point is just to throw this out for discussion, see if any of you have tried this, and also hopefully get more of you out there to start encoding like this yourself.

I use DVD2AVI and 'decode' to a wave file, then open the project file in gordian knot, observe the needed bitrate, crop it (to an even number), save the .avs script without any attention to the resolution (using 4.xx only of course), then I open the .avs file up with notepad and comment out the resizing line, then I pass that to virtualdub, open the wave file, set up my encodes, and let it run.

(I've tried Azid/lame but I seem to run into synchronization problems often when I use this method. Sometimes it works though..
Doom: I've followed your guides..still end up with sync problems though.)
Anyone know of any filters that can be loaded on your system to boost the mp3 audio of the divx while playing movies back? When AIM sounds go off with my speakers way up it's painful

Ok, sorry for writing so much, lol.

Look forward to hearing from ya'll.


-Ozymandis
Ozymandis is offline   Reply With Quote
Old 6th December 2001, 06:42   #2  |  Link
Ozymandis
Registered User
 
Join Date: Dec 2001
Location: NC
Posts: 7

Meant to say 1 cd cropped-only and 1cd cropped/resized.

Oh, I encode using two dual Athlon MP systems - 2 x 1.2ghz and 2 x 1.4ghz. Quite nice On resized material using Nandub I get 40-45 fps or so on the faster machine, 34 or so using divx 4.11 (with 80% cpu utilization). Running the mpeg2 decoding through avisynth distributes the load fairly well, obviously.
Ozymandis is offline   Reply With Quote
Old 6th December 2001, 11:43   #3  |  Link
petgun
Registered User
 
Join Date: Nov 2001
Posts: 2
Re: Resizing not necessarily a good idea with Divx 4.11

Hi,
Quote:
Originally posted by Ozymandis
....it's appeared pretty clear to me that -not- resizing results in a much clearer picture.....
I made the same experience!

cu,
peter
petgun is offline   Reply With Quote
Old 6th December 2001, 12:31   #4  |  Link
Ookami
Xe-Rotaredom
 
Ookami's Avatar
 
Join Date: Oct 2001
Location: Croatia
Posts: 1,029

Sound:

You can use Sasami2k and/or the TFM audio filter...

Resizing:

But remember you HAVE to resize to get the correct AR!
__________________
"Only those who attempt the absurd achieve the impossible."
Ookami is offline   Reply With Quote
Old 6th December 2001, 14:14   #5  |  Link
Doom9
clueless n00b
 
Join Date: Oct 2001
Location: somewhere over the rainbow
Posts: 10,570

resizing obviously has a negative impact in quality.. but if you use an appropriate resize filter (and imho for divx4 the solution can only be sharp bicubic as divx4 has much more tendency to blur things than divx3) the advantage of having much more bits/pixel will in the end result in a better overall movie experience, especially in demanding scenes.
__________________
For the web's most comprehensive collection of DVD backup guides go to www.doom9.org
Doom9 is offline   Reply With Quote
Old 6th December 2001, 15:38   #6  |  Link
ppera2
Registered User
 
ppera2's Avatar
 
Join Date: Oct 2001
Location: Lands of confusion
Posts: 1,217

Ozymandis, just tell us which player you use to watch such encoded movies ?

Because only few can change aspect ratio.

Of course, some optic put between monitor and viewer can help too .
ppera2 is offline   Reply With Quote
Old 6th December 2001, 17:13   #7  |  Link
b0b0b0b
Registered User
 
b0b0b0b's Avatar
 
Join Date: Oct 2001
Posts: 261


bsplay and zoomplayer and pdivxng can all squeezoom your divx when playing. I've made squeezoomable divx's too; I agree sometimes they look better. I'm not calling them anamorphic because I think that anamorphic usually means 720x480 => 16:9 (640x360) @ playback. I'm including divx's I've made that are 720x480 => 4:3 (640x480) @ playback.

I think it ends up being a tradeoff in whether you spend more bits on finer detail (when you don't resize) vs overall picture (when you shrink before encoding). "Kids" is a good example; in the opening scene it was nice to be able to preserve the individual strands of the girl's hair rather than losing the detail by shrinking the image.

Another argument for making squeezoomable divx's is if your display device is better than TV resolution, such as on a computer monitor or projector. They can render the higher frequency information you're preserving. If you're just going to watch it on a regular TV I don't think there would be a point to not resizing.
b0b0b0b is offline   Reply With Quote
Old 6th December 2001, 19:23   #8  |  Link
Ozymandis
Registered User
 
Join Date: Dec 2001
Location: NC
Posts: 7

For reference, I usually use powerdivx or radlight. I like the keyboard seeking in radlight.

As far as viewing the movies on a TV is concerned, it's definitely best to resize since you would almost certainly otherwise have problems exporting the display with some video cards, your AR would be correct, and it would probably encode faster, depending on how much the resolution is being decreased.

I'm your typical college student, though, with two big monitors in the room and a smaller TV

Doom: I've learned a LOT from your guides, thanks btw
As for losing quality though..I really just must disagree...I've taken stillshots at various movie frames from all of these multiple encodes I've done, in high action scenes, still scenes, etc, and in all cases not having resized looked drastically better. (When resizing I kept my bits/pixel in range as advised in your guides). I also did one pass while skipping frames (to get the bits/pixel) to guestimate the best resolution to set. This always kept my real first pass fairly close to what I had desired.

I kept doing this for every movie because I couldn't believe that everyone else would be resizing with the new codec still if the visual difference I'd seen held true.

I -definitely- agree that with 3.11, this is necessary. I just don't think that it's necessarily the best way to go with 4.xx (if it's not critical to have AR absolutely -perfect-).

When resizing, the overall quality of the image is only being improved because you're trusting your resizing algorithm to subtract information from the picture, rather than the codec. I think that the new codec is much more intelligent about what data should be "removed", though, than a non-adaptive resizing algorithm.

I'll see if I can't make some still shots tonight and post them tomorrow.

As b0b0b0b said, hair is always a good thing to look at. Preferably blond

Hey, I just tried the TFM filter. Works great! Thanks Ookami.
Ozymandis is offline   Reply With Quote
Old 21st January 2002, 11:23   #9  |  Link
nikthebak
Registered User
 
Join Date: Nov 2001
Location: Finland
Posts: 73
Conclusions about DivX 4 resizing

Greetings,

I would like to bring this thread back up since DivX 4 is gaining popularity rapidly and more people have results and opinions on this matter. And I would like to have some confirmed guidelines for DivX 4 resizing issue.

Every single movie I've encoded has been anamorphic 16:9 R2 PAL DVD and I have no reason to believe this is going to change so everything I ask here applies to these kind of sources only. I usually target 1CD-rips with ~120 ABR MP3 audio, 2CD with AC3 only on extremely rare occasions and/or very long movies.

My official video encoding process goes as this;

GKnot for cropping & resizing ->
VDub for first pass ->
DivX4Log for adjusting quantisizers ->
VDub for second pass ->
Audio and others

I usually apply Temporal Smoother of (1) to (4) depending on noisiness of the movie and results of compressiblity check.

The problem is that numerous people have claimed that plain cropping and perhaps only vertical resizing produces better results than resizing to i.e. 640x or 512x widthwise, even in 1CD cases. So simply, is this true?

If the answer is yes, which method would be preferable, cropping and applying bicubic resizing in order to get correct aspect ratios or just plain commenting out the resizing part from the .avs file? When using the latter method there will be absolutely no quality decrease because of resizing but the resulting file will be playable through aspect ratio-aware players only. So is it worth the additional trouble to leave out resizing or are the possible quality improvements negligible?

If the answer is no or we are in situation of insanely low bits per pixel values then we just have to resize. In these cases, are DivX 4's algorithms trustworthy enough so whe can always choose sharp bicubic or should we choose perhaps medium bicubic for additional compressibility?

P.S.

Forgive me for sounding like a total newbie but magnitudes of DivX 4 improvements and changes to the encoding doctrines are very profound indeed. The old DivX 3.11 lore has become obsolete and I do think quite a lot of us are currently struggling with information overflow on this subject!

P.P.S.

I would be delighted of any responses since I'm on the verge of changing my encoding doctrine from "to resize" to "not to resize" also!
__________________
niktheblak
nikthebak is offline   Reply With Quote
Old 21st January 2002, 19:26   #10  |  Link
serbersan
Registered User
 
Join Date: Oct 2001
Posts: 116
Well I use Gknot - Divx4, How I could encode a movie without resizing?

I have proved to delete the line in .avs file where is the resizing, but then I have errors with VirtualDub.

Please, tell me how I do it?

Thanks.
serbersan is offline   Reply With Quote
Old 21st January 2002, 19:28   #11  |  Link
trbarry
Registered User
 
trbarry's Avatar
 
Join Date: Oct 2001
Location: Gainesville FL USA
Posts: 2,092
We've discussed here about how some machines have trouble playing large resolutions but that is getting better with newer faster machines.

And we've discussed the change between Divx3 & Divx4 as far as the need for resizing.

But I don't think anyone has mentioned the decreasing media costs.

CD-R's are much cheaper than they used to be and even double sided DVD-R's can now be had for $5-6. This can't help but influence everybody's preferences for quality vs space.

I think that, except for compression technology improvements, this will cause us all to gradually increase both the bits / pixel and the number of pixels we are willing to use. After all, this is about getting the maximum bang for the buck and that changes as the cost of our toys and media do.

If 2 sided DVD-R's were $0.50 and everybody already owned a DVD-R burner how many of us would still be downsizing or making 1 CD rips.

So maybe it is just a matter of time.

- Tom
trbarry is offline   Reply With Quote
Old 21st January 2002, 23:13   #12  |  Link
zulu
Registered User
 
zulu's Avatar
 
Join Date: Nov 2001
Location: Germany, KS
Posts: 269
Quote:
Well I use Gknot - Divx4, How I could encode a movie without resizing?

I have proved to delete the line in .avs file where is the resizing, but then I have errors with VirtualDub.

Please, tell me how I do it?

Thanks.
i'd like to know that, too!
__________________
::zulu's devpage::
zulu is offline   Reply With Quote
Old 22nd January 2002, 09:21   #13  |  Link
dvdyke
Registered User
 
Join Date: Oct 2001
Location: UK
Posts: 42
To trbarry. For personal copies yes. For those moving data over the internet. Not yet. The idea was originally to get movie sizes down to a 1 or 2 CD size which was downloadbale over broadband connections. Or at least to get movie sizes down as much as possible so that whatever connection you use you can get the movie faster and make it a more viable method to obtain movies. If we could get a current 1 CD movie into the space of 100 megs at the same quality I no doubt expect we would see people putting out more movies at that size to download or 1 CD movies with a 600-700% increase in quality (Oh what a piep dream. Or is it given that only a year or two ago we did not think DiVX would do what it currently does).

When DVD writers become cheaper and media is like CDR is now we still have the issue of bandwidth. I doubt bandwidth will go up substantially for a few years yet. When we are all on 10mbit or 100mbut links I will no doubt be grabbing DVD sized download yes. But until then we have to make the most of what we have and I think cheap DVD writers/media will get there 1st. The other way would be to trade media via snail mail of course

Anyhow. Back to the topic. If any technical people with good eyes can give some definitive answers on whether no resizing and only cropping gives better results with DiVX4.xx I am very interested to know.
dvdyke is offline   Reply With Quote
Old 22nd January 2002, 16:34   #14  |  Link
nikthebak
Registered User
 
Join Date: Nov 2001
Location: Finland
Posts: 73
serbersan & zulu,

I never had any VDub complaints about not resizing.

For example, when I have following GKnot-created .avs file:

Quote:
# RESIZING
BicubicResize(704,384,0,0.75)
#
I just comment the BicubicResize() out like this:

Quote:
# RESIZING
#BicubicResize(704,384,0,0.75)
#
VDub accepts and compresses it without any problems. Just the aspect ratio of the resulting .avi is off. So where's the problem? Should VDub give errors or something?

Others:

For me 1CD is just a plain convience thing; A single, neat CD with nice printed covers which fits in my CD rack perfectly. 1 movie for 1 CD - nice and logical

Well, to be honest, I naturally go for 2CD rips if 1CD would be clearly inferior. This would be the case if AC3 audio preservation would be crucial or the movie was extremely long. DivX 4 just makes killer 1CD rips with much higher resolution than SBC.
__________________
niktheblak
nikthebak is offline   Reply With Quote
Old 22nd January 2002, 16:40   #15  |  Link
zulu
Registered User
 
zulu's Avatar
 
Join Date: Nov 2001
Location: Germany, KS
Posts: 269
thanks for your replay,nikthebak
__________________
::zulu's devpage::
zulu is offline   Reply With Quote
Old 4th February 2002, 16:49   #16  |  Link
ohliuv
Registered User
 
Join Date: Oct 2001
Location: Belgium
Posts: 113
mmm, just an idea:
Has anyone tried Bicubic directshow resize filter to correct the aspect ratio of non-resized DivX4

Last edited by ohliuv; 4th February 2002 at 16:54.
ohliuv is offline   Reply With Quote
Old 4th February 2002, 18:22   #17  |  Link
oddball
Registered User
 
Join Date: Jan 2002
Posts: 1,258
Yeah it works fine or try SimpleResize filter
oddball is offline   Reply With Quote
Old 4th February 2002, 19:29   #18  |  Link
Migsan76
Portuguese DivX Maker
 
Migsan76's Avatar
 
Join Date: Oct 2001
Location: Portugal
Posts: 61
Maybe a newbie question....

I always resize my rips, with Codec 3.11 and 4.12.

First i downsize five times each (high and Width) and obtain a resolution of 640x496. Then i apply the crop.

After read this thread i made a test and i have reach a result. It's possible than the ecoding of a non-resize movie be faster then a resize movie?

I used XMpeg 4.2a and DivX Codec 4.12


Sorry about the bad english
__________________
Keep On
Migsan76

For all goodies for your DivX Movies visit:
www.divxgoodies.web.pt
Migsan76 is offline   Reply With Quote
Old 12th February 2002, 13:09   #19  |  Link
ohliuv
Registered User
 
Join Date: Oct 2001
Location: Belgium
Posts: 113
can anyone share experience for optimal ranges of Bits/(Pixel*Frame) and the compressibility test % when encoding without resizing? Doom9 recommends ranges of 45-55% for the test and 0.20-0.27 for bits/pixel*frame. Are those still valid when no resizing is used?
How low can we actually go on those with DivX 4.12 and still get clearer image and good overall quality without resizing?

Last edited by ohliuv; 12th February 2002 at 13:12.
ohliuv is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 03:02.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2017, vBulletin Solutions Inc.