quick modul question

[cpuuk]

In the sticky it says that it is "highly recommend leaving them at their default values of 32(w) and 16(H)" and of course GK defaults to this setting. But when you view the vob with DVD2AVI ( during the writing the .d2v process) it show as 32(H) and 16(W). So which is right?

[manono]

Hi-

I'm not sure this answers the question fully, and I'm not sure it's 100% correct.

But, I'd say it's an apple to oranges comparison. That is, the [16x][32x] values you noticed are correct for the original DVD resolution, but it's MPEG2. And of course the DVD gets resized by 4:3 or 16:9 by the player which will make them then [32x][32x]. And what we're doing with GKnot is converting to MPEG4 where the W and H values are fixed and not resized. If you were to go Video-Clip And Resize, check the box in the upper right corner, and start moving the sliders around, then you'll see the values change up top. From the DVD2AVI.txt included in GKnot:
[Clip & Resize]

The more you clip, the faster the decoding speed is.
It's better to clip (if necessary) by DVD2AVI before sending to other editors through VFAPI.

There are some limitations on this filter due to MMX optimizations and field operations.
The value of [Left], [Right], [Top], and must be 2X (multiples of two)
[Left] + [Right] and [Top] + [Bottom] both must be 8X.
You should decide [Left] and [Top] at first and later modify [Right] and [Bottom].

The title bar of DVD2AVI shows possible multiples of the picture width and height.
[B]This multiple is very important for video codec processing.
For example, Matrox G400 won't enable DirectDraw Display when watching MPEG-4 unless it's [32X][16X].
So, I'd say there really is no contradiction between DVD2AVI and GKnot. However, the followup question might then be, "Well, why not do the cropping in DVD2AVI since he claims it's faster that way?" And I don't really know the answer to that one (Hakko?). I seem to remember reading once not to crop in DVD2AVI, but I forget the reason. Perhaps it has to do with us frame serving with AviSynth now instead of the much slower VFAPI method as in the "old days."

[hakko504]

Cropping in AVIsynth is unbelivably fast. It won't affect your speed at all in any way.
Cropping in DVD2AVI, or rather MPEG2DEC for AVISynth or vfapi-converter is also quite fast, but not quite as fast. It also means that you remove parts of the picture before any IVTC/Deinterlacing steps (or any filters at all for that matter), and that may cause undesirable effects such as motion not detected properly. If I recall correctly this is also limited to mod-16 resolutions, where AviSynth is using mod-2 or at worst mod-4.
Cropping in any stage after vfapi is not recommended: the whole picture must be converted to RGB first, and then cropped. Even though the crop itself doesn't slow down the process, the ConvertToRGB will.

[cpuuk]

Thx for the comprehensive answers guys :)

[hakko504]

Originally posted by cpuuk
Thx for the comprehensive answers guys :) There's no way to stop us...