creating a matrix?

[slavik]

where can I learn about the proper way to create a matrix for use with xvid?

[jon.schaffer]

Here's a reference thread to start:
http://forum.doom9.org/showthread.php?threadid=54147&perpage=20&pagenumber=1

Then, a tool to edit create/matrices:
http://forum.doom9.org/showthread.php?threadid=73666&perpage=20&pagenumber=1

[slavik]

That's a good thread (both of them)

is there one that teaches how to create a matrix? I understand what it means but what numbers should be put when?

[*.mp4 guy]

look at the mpeg standard matrix. you can get it from Ligh's cqm editor (use search) also keep in mid that h263 is all 32's and many people prefer it to all others. Imo The inter matrix should be more flatish and the intra matrix should be more mpeg-shaped however its all about personal preference.

edit: nvm about search, its the second thread linked.

[Didée]

Originally posted by *.mp4 guy
also keep in mid that h263 is all 32's
Sorry to step in, but this is false technical information. H.263 quantization does *different calculations* than mpeg quantization. By using an mpeg matrix with a constant number in all cells, one can achieve a result that is *similar* to h.263 quantization. But never the same.

BTW, the number to put in all cells for a "h.263-alike" mpeg matrix was somewhere between 20 and 24 (not sure atm), but in no case 32. This would be similar to that "ultimate matrix" thingie, which is only usable for *very* heavy compression. (And for that case, there are others doing the job better.)

[*.mp4 guy]

Ahh ok, Well I had heard a couple of things about the h263 matrix, one being that it wasn't a matrix and the other being that it was strait 32's, I had always assumed that what people meant by "its not really a matrix" was because matrixes have to have an intra value of 8 at the start and a matrix that is all one number (that isn't 8) couldn't follow this rule. Could it be possible (ignoring specs for a moment) to make different versions of h263 quantisization?

[Shinigami-Sama]

hmm
those aer nice start to understanding
but lack enough formation for me ot figure out what numbers to put in which slot
oh well
I geuss I'll read them again

[jon.schaffer]

Originally posted by Shinigami-Sama
hmm
... what numbers to put in which slot...
If one tells you what values must be used in each position, it would not be custom matrix anymore.
Open a matrix (e.g. MPEG standard) in Custom Matrix Editor. Modify it, see the encoding results and then modify it again according to the the type of compression you aim at.
Nothing is worth your own pratice and eyes...

[Shinigami-Sama]

I ment general rules of what to put in them for spefisfic effect or what have you
not hte end all value

[jon.schaffer]

Yes, but it's not easy to do, because, if I understood correctly (I did not dig it for times, now), one value in one position does not mean much: it depends on all the values before in the matrix.
So the rule of thumb must be the simplest one: high values vs low values.

But maybe I'm wrong - then someone will correct this, won't he/she?

[*.mp4 guy]

John.Schaffer is right, try changing one value in a matrix to the extreme, 90% of the time the result is unnoticible under normal veiwing conditions. For basic rules of thumb remember that higher values in the top left give you more blocking, while higher values in the botom right give you more ringing. Also remember that higher values throughout a matrix gives you a smoother look, while lower values give you a noisier look. Keep in mind that its possible to make a matrix that looks really good under specific circumstances, but that will do very badly in other circumstances. For instance a strait 32's matrix for the inter matrix will do good on harsh black/white barriers (by not ringing much) but it will also block, keep less detail and have worse ringing under other circumstances then just a simple strait 16's inter matrix. You should also not put to much stock in my opinion and as John.Schaffer said the most important thing is your experience.

[Shinigami-Sama]

ahhh
I see
well it;s getting less confusing now
maybe in the next few days I'll start making one, to test small clips with.
mustly music videos would be my source
hmm
I'm looking forward to testing :)