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.

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 :roll: . 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 :idea:

-kwag

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 :mrgreen:

Ok, here are the Q matrices I've come up with through some testing of CQ mode with noise variance of 2:

The rest of each matrix remains the same. Here it is in TMPGEnc.ini format, which is probably more convenient:

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.

Starting to test right now :D

I'm on the edge of my seat. It's very uncomfortable. Hurry! :mrgreen:

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" 8O :? ;).

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...

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 :mrgreen:

Edit: Were back on DSL :wink:

-kwag

@SansGrip,

Well, I tested your changes, but my result is the other way around 8O
The top image is with "SG 1" matrix changes.
Here's what I mean:

http://www.digitalfaq.com/archives/i.../2002/12/2.png

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

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 :wink:

http://www.digitalfaq.com/archives/i.../2002/12/3.png

Here's the current test matrix:

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

Here ya go, really blown up :mrgreen:

http://www.digitalfaq.com/archives/error.gif

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

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 :mrgreen: I could
tell you missed his insight and testing prowess. :mrgreen:

-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 :mrgreen: )

-kwag

:D
really,really,really!
Kwag,we are with you!
:)

Thanks jorel :D
Hopefully we'll keep optimizing MPEG-1 to a point where we drive DivX nuts :mrgreen:
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 :wink: ( That is, with both files about the same size :wink: )
And when you jack up the bitrate on both, and target a movie for 2 CDs, I really can't tell the difference anymore :mrgreen: ( Only that I can play my KVCD in my standalone, but not a DivX 8) )

-kwag

:!: looking good :D

Hi Kwag,

I’m just teasing :mrgreen: Don’t malign Divx too much. File prediction is now an important
part of the KVCD process, but remember when the idea started with Ozzie’s very long
avs script using Trim, then he cames up with SelectRangeEvery(). You’ll be interested
to know he got it from Divx’s compression test. I believe you are raising the bar for
picture quality for all methods of video backup to reach and that’s what’s important to
me. I used Gknot for some time and created a lot of Divx’s 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 what’s
happening at KVCD is very promising. :D

-black prince

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.