Avisynth: Overscan?
 

How much can I use overscan, I use 2 now, what happens if I raise it to 4, or 6?

hi Cheronaph,

use overscan=1 for 352x240(288), 352x480(576) and oversan=2 for any
higher resolution...to high values for overscan will give you black borders
on each side. You can try to use Letterbox(0,0,20,20) for 704x480(576)
resolution or Letterbox(0,0,10,10) for 352xXXX resolutions - this works on my TV, but actually you got to try how much overscan your TV-set uses...

regards, ***mfb***

at the moment i do not use overscan, my TV seems to play the kvcd best without

overscan won't do anything to the file. it just adds a border. so playback should not be affected by it.

I use 1 for 352x288, 2 for 352x576 and 3 for 528x576 or 544x576. I found out that my TV set crops the picture quite a lot so it's safe to use these values.

sure, but my tv doesn´t crop the picture, so i get a black border on the left and right if is use overscan

What should I use for 544x480, I'm using overscan 1 right now :?: And why should I switch to 2,3 or 4 when it doesnt efect the movie size or quality 8O

//Wolfi

Hi Wolfi,

It will affect the size of the black borders.
More black borders means more compression.
More compression means you can increase the CQ value and keep the same size.
More CQ value means more quality. :wink:

Oh nice :!: So what overscan is best to try, 2,3,4 :?:

//Wolfi

Well, it depends on your TV.
You will have to check what is the bigest overscan you can use without having the black borders visible on your TV.

Kane, are you sure that you get black borders on your TV whenever you use Overscan at all?
I don't think there's a TV that doesn't overscan anything... have you tried using no Overscan and this:
Letterbox(0,0,10,10) ?

yes i got black borders, when using overscan, i will try it with letterbox later

If you won't see any black boarders with overscan 4, is'nt it instead possible that the acters on the screen will look thinny if you rise overscan to much :?

//Wolfi

That's why you should overlap, instead of overscan, because the height will not be affected this way! :wink:

how do you use overlap?

So you mean I shouldnt overscan :?: Oke than, how do you overlap 8O never heard about it :?

//Wolfi

My movie dont look thin, I just wondered if it would if you rised the overscan to much :) But if I rise my overscan to, lets say 4, then is it possible to make the boarders to NOT to get bigger on the height :?: :?: It is no boarders on the sides of my TV screen but the said thing is that the upper boarder and the lowest boarder gets bigger :( So my picture gets quite small on the height :( Anyway to fix this without distoying the picture? Hope you understand what I mean with the "upper" and "lower" boarder :?

//Wolfi

Overscan will crop height and width, so that it doesnt affect the aspect ratio...to use Overlap, add the line:
Letterbox(0,0,32,32)
...to the end of your script, just before Legalclip() to add an overscan of 4 to only the left and right. :wink:

I'm a bit slow (as you aready know :? ).

1. So overlap ONLY affect the width boarders and NOT the height boarders :?:

2. If I decide to use overlap instead of overscan how should I put this line :arrow: GripCrop( width=544, height=480, overscan=3 )

Should it look like this: GripCrop( width=544, height=480) :?: and then I just add Letterbox(0,0,32,32) to make the width boarders bigger (ONLY) :?:

3. Were should I put Letterbox(0,0,32,32) in my script :?:

4. Wont my movie look very jerky if I only make the width boarders bigger without doing anything to the height boarders :?:

muaddib wrote about overscan:

"It will affect the size of the black borders.
More black borders means more compression.
More compression means you can increase the CQ value and keep the same size.
More CQ value means more quality."

5. So will this happen also if I use overlap insted of overscan :?:

6. " ...to the end of your script, just before Legalclip() to add an overscan of 4 to only the left and right. )

Should I remove the whole line GripCrop( width=544, height=480, overscan=3 ) to the end before Legalclip() and not only overscan=3. So it looks like this:

ConvertToYUY2()
LegalClip()
GripSize(resizer="BicubicResize")
STMedianFilter(10, 30, 0, 0, 10, 30)
SpaceDust()
unfilter(50,50)
temporalsmoother(1,2)
mergechroma(blur(1.58))
mergeluma(blur(0.3))
DctFilter(1,1,1,1,1,.5,.5,0)
GripBorders()
GripCrop( width=544, height=480, overscan=3 )
LegalClip()

Or am I wrong? Please try to answer all my questions, I'm confused 8O :oops:

//Wolfi

You can use Overlap to affect height borders too, just use Letterbox(16,16,16,16) to apply an Overlap Overscan of 2. But normally you would just use Letterbox(0,0,16,16) to only affect width borders. :wink:

No, just get rid of the Overscan part altogether, so it reads:
GripCrop(width=544, height=480)

Yep. :D

Right at the end, just before Legalclip() :)

No. Borders don't affect how the film plays. :wink:

Yep! You will get slightly less compression because you're not adding any borders top and bottom but you will still get the added benefit of more black borders.

No. Get rid of the overscan part, so your script should look like this:
ConvertToYUY2()
LegalClip()
GripCrop(width=544, height=480)
GripSize(resizer="BicubicResize")
STMedianFilter(10, 30, 0, 0, 10, 30)
SpaceDust()
unfilter(50,50)
temporalsmoother(1,2)
mergechroma(blur(1.58))
mergeluma(blur(0.3))
DctFilter(1,1,1,1,1,.5,.5,0)
GripBorders()
Letterbox(0,0,24,24)
LegalClip()
...to add an Overscan of 3. :wink:

Letterbox(0,0,8,8 ) = Overscan 1 Left and Right
Letterbox(0,0,16,16) = Overscan 2 Left and Right
Letterbox(0,0,24,24) = Overscan 3 Left and Right
Letterbox(0,0,32,32) = Overscan 4 Left and Right
:)