Quantcast CQ vs. CQ_VBR ... Very Interesting... - Page 8 - digitalFAQ.com Forums [Archives]
  #141  
12-28-2002, 12:46 PM
SansGrip SansGrip is offline
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Quote:
Originally Posted by kwag
Ok, go back to the previous page and look again. That's a darker sample, so you can see the results better. It's still only a very slight improvement, but it's there, and it can be optimized.
It's definitely getting rid of most of those "striped" artifacts, and so is an improvement over the regular KVCD matrix for sure.

Do you think there is a way we could change the Q matrix so that Blockbuster has an effect on CQ mode? For me, CQ mode is not an option if it doesn't allow me to reduce blockiness, since those are the artifacts I find most annoying...

The ideal solution would be CQ mode with a modification to the Q matrix so that we can dither with Blockbuster if necessary, since CQ mode seems far better at keeping Gibbs under control than CQ_VBR.
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  #142  
12-28-2002, 01:01 PM
kwag kwag is offline
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Quote:
Originally Posted by SansGrip
Do you think there is a way we could change the Q matrix so that Blockbuster has an effect on CQ mode? For me, CQ mode is not an option if it doesn't allow me to reduce blockiness, since those are the artifacts I find most annoying...

The ideal solution would be CQ mode with a modification to the Q matrix so that we can dither with Blockbuster if necessary, since CQ mode seems far better at keeping Gibbs under control than CQ_VBR.
Could it be that internally in TMPEG, it uses some sort of "High Pass" filter on CQ mode . Then only frequencies above a treshold are beind encoded, and that's why Blockbuster doesn't have the same effect
This is something I thought last night after I saw your samples . If this is the case, we're fried . Have you tried your noise generator filter and see if you see the noise with CQ as it is seen with CQ_VBR

-kwag
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  #143  
12-28-2002, 01:02 PM
SansGrip SansGrip is offline
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Quote:
Originally Posted by kwag
This is something I thought last night after I saw your samples . If this is the case, we're fried .
I'm getting promising results with some Q matrix modifications. I'll let you know in a while .
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  #144  
12-28-2002, 01:06 PM
kwag kwag is offline
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Quote:
Originally Posted by SansGrip
Quote:
Originally Posted by kwag
This is something I thought last night after I saw your samples . If this is the case, we're fried .
I'm getting promising results with some Q matrix modifications. I'll let you know in a while .
Looks like 2003 will bring us newer levels of MPEG-1 quality
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  #145  
12-28-2002, 01:48 PM
SansGrip SansGrip is offline
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Ok, here are the Q matrices I've come up with through some testing of CQ mode with noise variance of 2:

Code:
Intrablock:

 8 16 20  8 10
16 24  8 12
20  8 16
 8 12
10

Non-intrablock:

16 26 20 12 20
26 24 12 14
20 12 20
12 14
20
The rest of each matrix remains the same. Here it is in TMPGEnc.ini format, which is probably more convenient:

Code:
Name5="SG 1"
ReadOnly5=0
Intra5_0=8 16 20 8 10 27 29 34
Intra5_1=16 24 8 12 27 29 34 37
Intra5_2=20 8 16 27 29 34 37 38
Intra5_3=8 12 27 31 36 37 38 40
Intra5_4=10 27 29 36 39 38 40 48
Intra5_5=27 29 34 37 38 40 48 58
Intra5_6=29 34 37 38 40 48 58 69
Intra5_7=34 37 38 40 48 58 69 79
NonIntra5_0=16 26 20 12 20 26 28 30
NonIntra5_1=26 24 12 14 26 28 30 32
NonIntra5_2=20 12 20 26 28 30 32 34
NonIntra5_3=12 14 26 30 32 32 34 36
NonIntra5_4=20 26 28 32 34 34 36 38
NonIntra5_5=26 28 30 32 34 36 38 40
NonIntra5_6=28 30 32 34 36 38 42 42
NonIntra5_7=30 32 34 36 38 40 42 44
Of course, this may not be your fifth entry so some care will need to be taken when pasting it into the INI file .

With this Q matrix I notice a significant improvement in blockiness when used with CQ and Blockbuster variance=2, yet a slightly lower file size compared with CQ_VBR.

I'm not sure what other effects this change might have, for example when not adding noise at all. I'd be very grateful if people could test this one out and tell me what they think.
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  #146  
12-28-2002, 01:51 PM
kwag kwag is offline
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Starting to test right now
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  #147  
12-28-2002, 01:55 PM
SansGrip SansGrip is offline
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Quote:
Originally Posted by kwag
Starting to test right now
I'm on the edge of my seat. It's very uncomfortable. Hurry!
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  #148  
12-28-2002, 02:09 PM
SansGrip SansGrip is offline
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Quick update: This matrix produces significantly higher file sizes than the KVCD matrix when used without noise. I'm starting to think that CQ mode has an optimal matrix depending on whether or not noise is added .

Edit: Though it is also less blocky. Less blocky == larger file size.

I'm currently trying something different...

Edit 2: At least, I was. Apparently I'm to go to the mall with my family, so I can "spend some time with them" .
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  #149  
12-28-2002, 03:39 PM
Jellygoose Jellygoose is offline
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SansGrip Quote: "Do you think there is a way we could change the Q matrix so that Blockbuster has an effect on CQ mode? For me, CQ mode is not an option if it doesn't allow me to reduce blockiness, since those are the artifacts I find most annoying... "

I see the artifacts you are talking about in your samples. I'd highly recommend though that you do tests with higher resolutions for this purpose...

here's what you should look at SansGrip:

Try at 704x480:

CQ mode with and without blockbuster noise using a variance of one.
CQ_VBR mode with and without blockbuster noise using the standard value for variance.

compare these results. in my case they speak louder than words for CQ with blockbuster variance 1.
anyway I'm sure a new matrix will solve the little side effects for CQ...

CQ_VBR might be better for low resolutions though...
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  #150  
12-28-2002, 06:56 PM
kwag kwag is offline
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Quote:
Originally Posted by SansGrip
Quote:
Originally Posted by kwag
Starting to test right now
I'm on the edge of my seat. It's very uncomfortable. Hurry!
Sorry for the late reply but my DSL line ( F#%@ Verizon ) is down. Nice!, it had to go down today, Saturday. So we'll probably be down till monday! "DAMN" Here I am on a 56K dialup, and it hurts. So I won't be able to post any samples, and only limited browsing DAMN!
Sorry to keep you on the edge of the chair for so long

Edit: Were back on DSL

-kwag
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  #151  
12-28-2002, 07:55 PM
kwag kwag is offline
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@SansGrip,

Well, I tested your changes, but my result is the other way around
The top image is with "SG 1" matrix changes.
Here's what I mean:



Also note the grass(or weeds) just barely touching the shoulders. You'll see the bottom image is slightly more dithered.

Edit: Only used "LegalClip" on this one. No other filters were used.

-kwag
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  #152  
12-28-2002, 09:31 PM
kwag kwag is offline
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Here's another one, with even more tweaks on the matrix. This one 704x480. I'll let you guys do the red squares on this one



Here's the current test matrix:

Code:
Name26="KVCD Notch (BETA-2)"
ReadOnly26=0
Intra26_0=8 6 8 22 26 27 29 34
Intra26_1=6 7 10 26 27 29 34 37
Intra26_2=8 10 14 27 29 34 37 38
Intra26_3=22 26 27 31 36 37 38 40
Intra26_4=26 27 29 36 39 38 40 48
Intra26_5=27 29 34 37 38 40 48 58
Intra26_6=29 34 37 38 40 48 58 69
Intra26_7=34 37 38 40 48 58 69 79
NonIntra26_0=16 16 16 16 16 16 16 16
NonIntra26_1=16 16 16 16 16 16 16 16
NonIntra26_2=16 16 16 16 16 16 16 16
NonIntra26_3=16 16 16 16 16 16 16 16
NonIntra26_4=16 16 16 16 16 16 16 16
NonIntra26_5=16 16 16 16 16 16 16 16
NonIntra26_6=16 16 16 16 16 16 16 16
NonIntra26_7=16 16 16 16 16 16 16 16
I'm leaving Non Intra as default values. Only concentrated on Intra section. The file size is "barely" larger than the original KVCD matrix.

I'll try this now at 352x240 and post results.

-kwag
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  #153  
12-28-2002, 09:57 PM
kwag kwag is offline
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Here ya go, really blown up



Edit: The CQ used here, 25, is really low for a regular picture. I used 25 to force the low frequency areas to be blocky, and make the results and test more visible.

-kwag
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  #154  
12-29-2002, 12:54 AM
black prince black prince is offline
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Hey Kwag,

The KVCD test Matrix 704x480 Notched Filter picture is clearly better
I seems the lower resolutions 352x240 don't show as much improve-
ment as SansGrip suggested. I already get great encodes at this
resolution (704x480). I'd be curious to see how much improvement
this would show with a short clip of a fire, water and fast action scenes.
Gibbs effect has vanished at higher CQ's but would this test Matrix
improve it at lower CQ values. I see you still have more tweak-
ing to do, but this looks very promising. All you needed was for
SansGrip to come back and encourage you on I could
tell you missed his insight and testing prowess.

-black prince
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  #155  
12-29-2002, 01:01 AM
kwag kwag is offline
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Quote:
Originally Posted by black prince
. All you needed was for
SansGrip to come back and encourage you on I could
tell you missed his insight and testing prowess.

-black prince
You all encourage us to push all this stuff to the limits. And the "NAH" sayers at other sites encourage us to go beyond the standards and over the limits ( which then pushes them to oblivion )

-kwag
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  #156  
12-29-2002, 01:12 AM
jorel jorel is offline
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Quote:
Originally Posted by kwag
Quote:
Originally Posted by black prince
. All you needed was for
SansGrip to come back and encourage you on I could
tell you missed his insight and testing prowess.

-black prince
You all encourage us to push all this stuff to the limits. And the "NAH" sayers at other sites encourage us to go beyond the standards and over the limits ( which then pushes them to oblivion )

-kwag


really,really,really!
Kwag,we are with you!
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  #157  
12-29-2002, 01:25 AM
kwag kwag is offline
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Quote:
Originally Posted by jorel



really,really,really!
Kwag,we are with you!
Thanks jorel
Hopefully we'll keep optimizing MPEG-1 to a point where we drive DivX nuts
I'll post some screenshots on that tomorrow, where you can see MPEG-4's advantage ONLY on low bit rate and low action scenes, and you can see KVCD MPEG-1's CLEAR advantage on high motion scenes ( That is, with both files about the same size )
And when you jack up the bitrate on both, and target a movie for 2 CDs, I really can't tell the difference anymore ( Only that I can play my KVCD in my standalone, but not a DivX )

-kwag
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  #158  
12-29-2002, 05:39 AM
gonzopdx gonzopdx is offline
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looking good
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  #159  
12-29-2002, 10:36 AM
black prince black prince is offline
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Hi Kwag,

Quote:
Black prince write:
All you needed was for
SansGrip to come back and encourage you on I could
tell you missed his insight and testing prowess.
Iím just teasing Donít malign Divx too much. File prediction is now an important
part of the KVCD process, but remember when the idea started with Ozzieís very long
avs script using Trim, then he cames up with SelectRangeEvery(). Youíll be interested
to know he got it from Divxís compression test. I believe you are raising the bar for
picture quality for all methods of video backup to reach and thatís whatís important to
me. I used Gknot for some time and created a lot of Divxís only to be played on my
PC. I wanted more portability in playing movies with the best picture quality possible.
KVCD has not disappointed me and others. You are reaching for picture quality
that could very well become the standard for others to reach, not just Divx. I wish I had skills
like you, SansGrip, and other technical developers, but I know enough to realize whatís
happening at KVCD is very promising.

-black prince
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  #160  
12-29-2002, 10:39 AM
SansGrip SansGrip is offline
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Quote:
Originally Posted by kwag
Well, I tested your changes, but my result is the other way around
Edit: Only used "LegalClip" on this one. No other filters were used.
Remember that I developed the matrix in conjunction with Blockbuster, variance of one or two. My reason for doing this was not so much to come up with good matrices for use with CQ mode and Blockbuster, but to show that it's going to be pretty difficult (if not impossible) to come up with matrices that are optimal for all circumstances, at least with CQ mode.

At the moment for me it's looking like CQ mode is better for high resolutions, provided by "better" you mean "less Gibbs" and not "fewer blocks". Perhaps the reason we're getting less Gibbs is because it's essentially ignoring that Blockbuster noise we're adding, and so can spend a lot more bits on the high-freq components?

It is somewhat discouraging that I see great improvements in low-freq quantization using my matrices providing I use Blockbuster, but no improvement (or even a reduction in quality) when not using it. This seems to make CQ mode much more unpredictable than CQ_VBR.
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