My test seems to confirm your conclusions. GOP length 8 turned out to be average 997kbps, Q=2,12. The length 15 was average 998kbps, Q=2,05. I haven't checked the graph thoroughly but as you've already examined the test results, it seems that there is no need to. Too bad, this could have been a revolution :twisted:

Kwag

Have you made some encodings with the x3 template??? Which were your results??? I only use this template because the x2 showed me blocks sometimes, i would like to go back if that gives me more quality...

Regards,
DaDe.

Hi DaDe,

The same GOP results with every template. :roll:
The x3 is still the best balance for quality/space ratio, specially on action scenes. Even viewed on a HDTV, the x3 is very close to DVD sharpness, and will exibit less blocks than the x2. If your movie is a drama or low action, the the x2 will look just near perfect.

-kwag

Hi All,

Must be some hot and heavy PM's between Christopher, SansGrip,
Kwag and other experts about GOP effecting file size. . :lol: It's
been very quite for at least 2-3 hours. I hope there's some sort of
answer to this issue. Either a new and revolutionary discovery will
emerge or this was all an exercise in futility :? Either way, it's fun to
see this much activity going on to solve problems. :D :D


-black prince

Hi black prince,

I think we're all crying now :cry: . Specially me, since I started the thread, I'm banging my head against the wall :twisted: :cry: :twisted: :cry:
Maybe more tests have to be conducted, and I hope my last test was wrong. I never give up :D , so I'm still looking for the jack pot :wink: . Still, it's great to brainstorm. I hope something great comes out of this :?

-kwag

Actually I quite enjoyed the flurry of activity :D. As for my silence, I've been doing dishes and cooking supper and so on ;).

I still think there's more room to tweak. I mean, with so many variables it's highly unlikely that we've hit upon the absolute best possible way of doing it.

For example, I've always wondered if "scene change detection" should be on or off (I imagine kwag's already tested that one), but also it's worth taking a look at the "force picture type" settings. I think we could squeeze some joy out of that dialog.

I too am looking over several ideas. I agree with SansGrip in that there is always room for improvement. Just a side note to let everyone know that the KVCDEncoder project is not dead. I have been going over several ideas from the FFmpeg and Xvid projects. And Kwag has been searching for a bug in your current codebase. I sure that things will pickup after the holidays.

Are you running on a generator down there or did they get the power back up yet? :)

I was one of the lucky ones, never lost power, but boy there was ice everywhere.

Tell me about it... My web server is located outside Raleigh and was down for about 5 days before the admin was able to find a couple of generators for sale :).

Nice to see I'm not the only "northerner" here .. :wink:

You're still north to me -- I'm in Kitchener ;).

Is that why you're always in the Kitchen cooking supper :mrgreen:

Ok, here we go again :D
I've been busy for the past 4 hours, because I just don't give up 8O
This is the GOP I've been testing, after trying out so many combinations, that it's driving me crazy.

Try this out: 1-12-2-1-24 against 1-36-3-1-36.
With KVCD Predictor, and using the 1-12-2-1-24, the CQ_VBR value is lower for the same target file size as with 1-36-3-1-36. However, the Q factor is lower, meaning higher quality, for the same file sizes. There are LESS visible artifacts with 1-12-2-1-24 than with 1-36-3-1-36. I've made several tests now, and with the same file size with both GOPs, the difference in quality is visible, specially around complex objects. The 3 B frames used in the current GOP, while giving higher compression, degrade the video quality slightly. So with 2 B frames and a MAX number of frames per GOP of 24, I've found that we get more punch (quality) for the same given file size as 1-36-3-1-36. Here's a clip of "Red Planet" with this new GOP: http://www.kvcd.net/clip3.m1v
The clip is a cut out from the file prediction sample, which is 11.83MB.
And THIS is the quality that will go on ONE CD-R at 704x480, as predicted with SansGrip's KVCD Predictor. Please try it out, and make some samples and compare to the the 1-36-3-1-36 GOP. I believe what I have found here is definitively a better GOP that what we had before. I only tried this with 704x480 PLUS template, but I assume it will work the same with the other templates, based on all tests made in this thread.
We need feedback on this!. This GOP could probably be optimized even further, but I'm tired now. And the result I see on the sample is so good for the resolution, that I don't know if it needs to be further optimized. :roll: I'll leave that up to anyone who would like to try and improve on this.

-kwag

Hey Kwag i s wondering if could see the avs script for red planet. That looks pretty damn good at 704X480. You da man kwag. So is compression still greater with 1-36-3-1-36 or the new gop using only 2 b frames.

Thanks Branden

HI,

Instead of searching and "optimal" GOP for each CQ/resolution/movie, and at the same time trying to do the file prediction, perhaps we can use a compromise solution and narrow the options, like a low-CQ GOP and a hi-CQ GOP.

With only a couple of GOPs the search space is reduced and it can be easier to find "sub-optimal" parameters that may not be as good as if we had exhaustively searched every possible GOP for every CQ for a given movie, but that are still better than always use the same GOP for every CQ.

Here's what I used for that sample:

I didn't use any "Sharpen" because I think at that resolution it's not needed. The complete encode came out to 756MB, and it was supposed to be ~713. So I guess it throws off the KVCD Predictor formula a little. Based on my original prediction sample size, 11.88MB, using the formula with a factor of 1.0, the result is 759MB. So it seems that for this GOP, the factor is 1.0 and not 0.95.

-kwag

Hi Kwag,

Here's my results:

Kx3 (528x480), FitCD=496x448, Movie Length= 8304 seconds

LoadPlugin("E:\DVD Backup\2 - DVD2SVCD\MPEG2DEC\MPEG2DEC.dll")
LoadPlugin("E:\DVD Backup\2 - DVD2SVCD\BlockBuster\BlockBuster.dll")
LoadPlugin("E:\DVD Backup\2 - DVD2SVCD\LegalClip\LegalClip.dll")
mpeg2source("D:\Temp\movie.d2v")
IL = Framecount / 100 # interval length in frames
SL = round(Framerate) # sample length in frames
SelectRangeEvery(IL,SL)

CQ_VBR=22.42 GOP=1-12-2-1-24 File size= 24,517,706
CQ_VBR=22.42 GOP=1-23-3-1-36 File size= 23,373,174

I used Tmpgenc to mask the borders and resize the video. :)
Blockbuster noise causes file size to fluctuate and sharp just
increases file size. Picture quality was great for both GOP's.
Will you still resize and mask borders with Tmpgenc or has that
changed :?: I like the fact that you're always searching for
better picture quality/smaller file size/faster process. It's what's
got us here and that's why I stick with this forum. :D Get some rest. :?

-black prince

Hi kwag!

For a 1CD with 704x480 I presume that the CQ_VBR should be low.
Is this gain in quality true for higher CQ_VBRs? (lets say 2CDs 704x480)
Or for higher CQ_VBRs the quality is high enough that we could use the other GOP and won't notice the degeneration in quality?

Cheers!

Hi black prince,

Rest, what's that :lol:
Your results are 100% consistent with mine :D . Now if you lower the CQ_VBR and encode again with the 1-12-2-1-24 until the file size matches the one encoded with 1-36-3-1-36, you'll still have better quality! Here is a screen shot of bit rate viewer showing my two sample encodes. The file size difference from one file to the other is only 5KB. So that's negligible.

Here's the first with a GOP of 1-36-3-1-36:
http://www.digitalfaq.com/archives/i.../2002/12/1.jpg
The peak Q level is 15.14, the average bit rate is 863KB and the average Q. level is 3.86.

And here's the one with 1-12-2-1-24:
http://www.digitalfaq.com/archives/i.../2002/12/2.jpg
Here, the peak Q. level is 13.93(better than above!), the average bit rate is 863KB (same) and the average Q. level is 3.53(Better than above!).

So you see, there is a difference, even though the file sizes are the same. This opens up a window of oportunity to try and continue to optimize the GOP until we can find the best Q factor while retaining the same file size.
Now I'm not crying anymore. I'm happy as a pig :lol:

-kwag