what is the purpose of the sharp feature in mdegrain?

[unclescoob]

If I use a prefilter to sharpen my image (like dfttest) and use it's sharp feature, would I still need to activate the sharp in mdegrain? What is it actually for? I assumed it was to sharpen your image, but now I'm not sure.

P.S. - Please explain this to me like I'm an idiot.

Thanks.

[LoRd_MuldeR]

I can't see such option for MDeGrain function :confused:
http://avisynth.org.ru/mvtools/mvtools2.html#functions

Maybe you are referring to MSuper?
MSuper(clip, int "hpad", int "vpad", int "pel", int "levels", bool "chroma", int "sharp", int "rfilter", clip "pelclip", bool "isse", bool "planar")

sharp: subpixel interpolation method for pel=2,4.
Use 0 for soft interpolation (bilinear), 1 for bicubic interpolation (4 tap Catmull-Rom), 2 for sharper Wiener interpolation (6 tap, similar to Lanczos).
Default is 2.

[unclescoob]

Yes, that's it. What's the purpose?

[LoRd_MuldeR]

MVTools uses motion compensation (https://en.wikipedia.org/wiki/Motion_compensation). The first step is always to call MSuper() function in order to create the so-called "super" clip, which contains multilevel (hierarchical scaled) frames data. The next step is to call MAnalyse() function, which will compute the motion vectors, based on the "super" clip. And, finally, functions like MDegrain() make use of these motion vectors - in degrain function, the motion vectors are used to distinguish "real" grain from motion.

Now, the "sharpen" option is for the MSuper() function, i.e. for the computation of the "multilevel frames data", which will be input to motion vector computation. So it does not influence the output of MDegrain() directly. It may influence the computation of the motion vectors. And thus it will also influence, indirectly, the MDegrain() output. But which "sharpen" value gives the most accurate motion vectors, I don't know. I would probably just stick with the default of 2 ;)

[unclescoob]

Okay, that makes sense.

Thanks!

[pandy]

How this all is related to MPEG-2?

[LoRd_MuldeR]

How this all is related to MPEG-2?

Not really. Moved.