Matrix, WDM

[morsafr]

When you switch between MPEG and H.263 "Quantization type" why is there any change in the matrix when you look at it with "Edit Quantizer Matrix..." ? :confused:

I'd like to understand something about XviD and other codecs.
I have read that we use the VFW interface. Does that mean that the codec is working in VFW or is it independant. I mean, will a WDM video application use the VFW->WDM wrapper of Microsoft when using the codec for compression ? :confused:

Thanks. :)

[trbarry]

I think the custom quant matrices are broken. I tried to make one a week or so ago just to see what the effects would be and it didn't seem to do anything.

- Tom

[Koepi]

you have to set the matrices to vry extreme settings to easily see the difference.

e.g. set all fields to 64 or 127.

(for intra AND inter matrix).

maybe that helps it a little.

[Chibi Jasmin]

I made the same experience with some of the newer builds (April). It's just that it doesn't save the values you enter.

If you create a custom matrix with an older build, and then install a newer one, the values are in, not sure, if they are actually taken then :-)

I didn't get into details with this, this is just what I remember, but something really seems to be broken with this...probably in the user interface...

[Klumsy]

I think that morsafr ment something different:

he thinks that with the 'edit quant matrix' option you can change the matrices for MPEG or H.263

But the custom matrix has afaik nothing to do with these two.
MPEG and H.263 may not be changed (only in the sourcecode ;))
The custom matrix is a third one that may be edited if you know what you are doing :D


Hope that's what you've been asking for

[-h]

Well the custom quant matrix actually quantizes using MPEG quantization, just with different values. H.263 uses a different method of quantizing altogether.

But anyway, it's probably broken in the current VfW frontend :)

-h

[morsafr]

I think I get the point for the matrix. It would be maybe more logical to enable the "Edit Quantizer Matrix..." button only when you select "MPEG-Custom" in "Quantization Type". But this is just a minor thing.

And about WDM / VFW stuff does anybody understand the meaning of my question ? :D