Quantcast KVCD: Tweaked Matrix vs. GOP vs. Avisynth? - digitalFAQ.com Forums [Archives]
06-10-2003, 04:12 PM
r6d2 r6d2 is offline
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Hello Kwag,

First of all, congratulations on a great job.

Your templates are based, if I understood correctly, on basically three key components:

1. A tweaked Q.Matrix, which is the same for all the KVCD/SKVCD templates.

2. A custom GOP structure: 1-24-2-1-24, which creates big GOPs by sparsing the I frames along the stream.

3. A "canonical" AVISynth script, very tweaked.

All three gotten after looong hours of work and test encoding.

Which of these three components would you say has more "responsibility" in achieving such a bunch of minutes on one CD?

Would you give a percentage figure, i.e., 40%-20%-20%?

I think it would be interesting to know, according to your experience, what these figures are, because for instance if 1 and 2 take, lets say, 80% of the credit, it may not be worth for us to spend too much more time tweaking your scripts further for every movie.


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06-10-2003, 04:29 PM
kwag kwag is offline
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Hi r6d2,

I can't give you an exact figure on percents, but I can say this:
The filters are extremely good, but on a perfect source, there will be barely any advantage, bacause there's nothing to clean
Of course, in reality every source has some defects, so the filters help reduce the overall mpeg size and this allows for encoding at a higher CQ.
The GOP has as very good role, but not very broad
You can only go so high and then you start messing your picture with "ghosting". That's why we max at 24 (25 for PAL). It seems to be a good compromise, together with the matrix, and produces sharp pictures and good compression.
The KVCD "Notch" Q. Matrix. No matter if your source is clean or dirty, the matrix is optimized for good quality/compression ratio, with an emphasis on DCT block reduction on low lit scenes by reducing quantization on the low frequency spectrum. The "Notch" pattern is the key to the matrix, and the results show
End result: The KVCD "Notch" Q. Matrix can be used on any encoder (Hardware or Software) that allows for custom parameter configurations, with great benefits on MPEG-1/2 quality and bandwidth savings.
This removes the notion of a "template" completely, unless it's being used in TMPEG

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