Avisynth: Gripcrop Picture a Bit Squeeze?

Glebix · #1 08-25-2004, 11:51 AM

I just noticed something negative about gripcrop resize. In my encode I had overscan-2 and I noticed that it only resizes the WIDTH of the pic but does nothing to the height

. So that makes the picture a bit squeezed and that is not nice at all.

source was 608x336 avi.

So why does it do that? Is it normal?

-Glebix

Dialhot · #2 08-25-2004, 12:06 PM

All is normal with GripCrop, you can trust me.

You probably imagine something that is not really done, or perhaps misuses the command.

What is your script ?

Glebix · #3 08-25-2004, 12:58 PM

Here's the script:

Code:

AviSource("E:\AviTestClip.avi",false) 
BlindPP(cpu=4) 
Blockbuster(method="noise",detail_min=1,detail_max=3,variance=0.1,seed=1) 
Convolution3D(1, 6, 12, 6, 8, 2.8, 0) 
GripCrop(720, 480, overscan=2, source_anamorphic=false,dest_anamorphic=false) 
GripSize(resizer="LanczosResize") 
Undot() 
TemporalSoften(2,7,7,3,2) 
DCTFilter(1,1,1,1,1,1,0.5,0) 
#Blockbuster(method="noise",detail_min=1,detail_max=10,variance=0.3,seed=5623) 
GripBorders()

Hey btw.. maybe you could also tell me where to put MSharpen filter in the script?

Dialhot · #4 08-25-2004, 01:03 PM

NEVER ENLARGE A VIDEO.
Your source is 608x336 so you shoudn't use 720x480 as destination resolution.

But this is only a question of quality, that is not your problem there.

Did you look at the encoded video with a player that allow you to FORCE the A/R to 4:3 (zplayer, bsplayer...) or did you use wmp ?

Glebix · #5 08-25-2004, 03:46 PM

Yes, I did use a program that can force the AR to 4:3. I even tried 2 programs just to be sure it wasn't just in the program or anything...

Here's 2 screens. 1 from the input and 1 from the output. I used overscan-2. In these you can see how it's a little squeezed.

input

output

As you can see the pic has squeezed only a pretty small amount so it's hard to see it just by looking at the pics.. But the difference can be seen when comparing the screens in some photo editing software or smt...

As for the resolution choice.. that was just a script for a little test so in a real deal I would've probably used 544x480 or w/e...

And hey what about that MSharpen thing?

Dialhot · #6 08-26-2004, 03:29 AM

As you says, on your snapshots it's hard to see something

. The diff between the two picture is due probably to rounding that is done by gripcrop. As any good resizer, gripcrop works in dimension divibles by 16 and to achieve that it must crop some pixels of the source !

Use FitCD or Moviestacker insteed of Gripcrop and you will see what happens to the original frame dimension.

Glebix · #7 08-26-2004, 08:24 AM

Ok I guess I get it now.. But the main thing to know is that i'm not doing anything wrong.

Should I put that MSharpen right after the AviSource?

incredible · #8 08-26-2004, 08:45 AM

Quote:

Originally Posted by Glebix

Ok I guess I get it now.. But the main thing to know is that i'm not doing anything wrong.

Should I put that MSharpen right after the AviSource?

I dont recommend that as ..

- Let BlindPPs Postprocessing do its job "untouched"! Means do NOT filter bewteen Avisource() and BlindPP()

- If your source gots artifacts, a sharpener would bring them even more out, especially mosquitos/ringArtifacts

- If you put a sharpener after a temporal filter, you will bring out more the inevitable resulting temporal denoising artifacts

- ... and finally if you sharpen an already enlarged! video, this would end up in Halo-Edges ... brrrrrr. As you would have to set the sharpen threshold very high so that the sharpen filter is able to detect the "smooth" edges AS edges.

And now you know why THAT script is called optimal script

Cause its not developed in only one evening

Glebix · #9 08-26-2004, 01:10 PM

Thx for that info incredible. I'm just gonna forget the whole sharpening thing then.