Quantcast KDVD: GOP Was Considerably Larger? - digitalFAQ.com Forums [Archives]
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07-13-2002, 09:33 PM
MoovyGuy MoovyGuy is offline
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Hey Kwag & All,

Just thought I'l let you know that I've decided to try to take on the task of grafting the new "K.Matrix" onto the KDVD templates.

As we've all already discovered, at full D1 the Andreas matrix was not optimal, so I thought I would try the K.Matrix, along with using CQ_VBR as well.

The early tests are in, and I will be posting numbers when I'm done, but basically the original KDVD template as well as using Kwags GOP in the standard DVD template (adjusted to the same frame rate & CQ) came out to roughly the same size (Approx 10 MB) in my sample encode ( a one minute clip from a Star Wars Ep 1 trailer).

The new template using the K.Matrix and the K.GOP was considerably larger at approx 14 meg, of course the quality was amazing by comparison, but then it was almost a third larger.

Anyways, I'll be messing with the quality setting some more to see where I can go with it and I'll post back with more info soon .....


Later y'all ....
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07-13-2002, 10:02 PM
kwag kwag is offline
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Hi MoovyGuy:

Actually, I'll be posting the KDVD template soon, but the only change in them is the integration of our Q. Matrix. The KDVD templates already create DVD quality, but with the inclusion of the new Q. Matrix, the size created is much smaller. There is no visual difference as far as quality is concerned by using the original TMPEG's "default" Q. Matrix and ours. But the file size difference is huge! I encoded the same 30 second sample clip from "The matrix", the same I posted for the analysis, and here are the file sizes:

Encoded with KDVD template and TMPEG's default Q. Matrix: 4,517KB.
Encoded with KDVD template and KVCD.Net's Q. Matrix: 4,365KB.

So as you can see, there's a giant space savings by using just the new Q. Matrix. I have left the encoding mode as CQ, and all other parameters the same, because the bit rate is already so high for the DVD templates, that there's no sense in changing the encoding mode. Give that a try!
Just load the KDVD template and change the Q. Matrix. That's it!

-kwag
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07-13-2002, 10:06 PM
MoovyGuy MoovyGuy is offline
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OK I'll give that a shot, I'll try that in about 3 mins as I'm waiting for my next test to complete.

I'll take the straight KDVD template and paste in the K.Matrix
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07-13-2002, 11:01 PM
MoovyGuy MoovyGuy is offline
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Hi All,

OK I'm back with some results from my tests with (subjective) observations as to visual quality.

Keep in mind that this series of tests included a 192 kbs stereo audio track. Under normal circumstances I would encode the audio externally. These were done this way to conserve time as I was buring these to DVD+RW for viewing on non PC devices.

Also, please note that my goal is not neccasarily to get the absolute best visual quality, but to get reasonable quality with a reasonable file size.


39 Second Test Clip (All encodes at full D1 (720x480))

9,066,500 Standard TMPGenc CQ 65
10,244,100 Original KDVD CQ 65
10,270,724 KDVD with Std Q.Matrix CQ 70

Standard template - Visual quality is horrible.
Original KDVD - Pretty good.
Of the Three in this series the one with the bolded item was by far the best visually.


9,971,716 KDVD & K.MAtrix 2xVBR-2250-1850-300
7,618,564 KDVD & K.MAtrix 2xVBR-2300-1368-300
11,923,460 KDVD & K.MAtrix 2xVBR-3500-2250-300
12,412,932 KDVD & K.MAtrix 2xVBR-5000-2350-300
14,850,052 KDVD & K.MAtrix CQ_VBR 20

Of the five in this series the one with the bolded item was very good at a decent file size. Of course the larger the file the better the quality. The last one using CQ_VBR was the best of the bunch, but the file size was unacceptable.


9,801,732 KDVD & K.MAtrix CQ 65
10,565,636 KDVD & K.MAtrix CQ 70-4000
10,807,300 KDVD & K.MAtrix CQ 70


My favorite of this entire test series is underlined above. It reached a good middle ground between quality and file size.

I found at the default CQ of 65 I could easily see artifacts in the stream, but at 70 they were greatly diminished. The increase in file size could be offset somewhat by lowering the max value, but this would not work in all cases. It'll depend on the content.

Anyway, that's my two cents ......

Later y'all
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