Border test for TV?

[pacohaas]

Can any Avisynth guru put together a border test for TV's?

here's what I mean:
our TV's typically cut off a few pixels on the edges and it would be nice to know exactly how much they cut off. If someone could put together a 480x480 avisynth script for instance where the color changed every 4 pixels or maybe every 2 from the outside in(like a bunch of colored squares on top of each other). Then the user could encode as an SVCD and put it on their TV and pause it to see how much edge they are missing.

obviously, a PAL version would be helpful.
maybe also one with VCD resolution would be helpful.

[rubic42]

On my TV the image is shifted to the right a good amount, such that some video game titles will get cut off.

Personally, after testing on my TV, I will only use a 16 pixel border on all sides when at full 720x480 NTSC resolution. 32 pixels was bleeding into the visible areas of my TV, and you never know how much worse/better other TVs may be.

I only did my testing on 16 pixels and 32 pixels, since those are multiples of the 16 pixel macroblock.

[$$$]

@pacohaas

Well, I'm not an Avisynth guru as I hardly use it. I prefer VD for convenience reasons. Actually, it would be quite easy to achieve what you want with VD and its resize filters. Take a blank video (eg an AVS script with just the line BlankClip()) and resize it with VD a few times while letterboxing with 4-pixel bars of different colors.

Of course with Avisynth you can do the same when you import Donald Graft's resize filter as it includes this functionality as well.

By chance I read yesterday somewhere here that Avisynth now provides this AdjustRGB filter which gave me the idea for a script to produce an overscan test clip. I haven't converted it to a VCD or SVCD yet (as I am at work now :D). Just convert to desired frame rate and be sure not to resize the clip with your encoder (source and target aspect ratio should be the same, I guess).



# clip resolution, choose any, eg 320x240, 352x288, 480x576

x=480
y=480

# the building blocks

hbar=MessageClip("",x-96,4,false,0,0,$ffffff)
vbar=hbar.bilinearresize(4,y)

# coloring

hr=hbar.rgbadjust(1,0,0,0)
hy=hbar.rgbadjust(1,1,0,0)
hb=hbar.rgbadjust(0,0,1,0)
hg=hbar.rgbadjust(0,1,0,0)

vr=vbar.rgbadjust(1,0,0,0)
vy=vbar.rgbadjust(1,1,0,0)
vb=vbar.rgbadjust(0,0,1,0)
vg=vbar.rgbadjust(0,1,0,0)

# putting them together and add some text

hall=stackvertical(hr,hy,hb,hg)
top=stackvertical(hall.Subtitle("I"),hall.Subtitle("II"),hall.Subtitle("III"))
mid=MessageClip("I: 1-16 II: 17-32 III: 33-48",x-96,y-96)
lft=stackhorizontal(vr,vy,vb,vg,vr,vy,vb,vg,vr,vy,vb,vg).subtitle("I II III",6,y/2)
rgt=stackhorizontal(vg,vb,vy,vr,vg,vb,vy,vr,vg,vb,vy,vr).subtitle("III II I",2,y/2)

stackhorizontal(lft,stackvertical(top,mid,top.flipvertical()),rgt)



Cheers
$

[pacohaas]

thanks man,

if anyone wanted to know, my combination of the Apex AD-5131 and a standard sony TV gives these results:

16 pixels on top
10 pixels on bottom
20 pixels on left
24 on right

I'll be encoding more of the video that I can actually see from now on, thanks again $$$.

[ulfschack]

But you use a 480x480 clip right? Since 480x480 is stretched to 640 (or something ... it's streched anyways) to get the 4:3 AR, you would have to add a border of different (bigger) width were you ever to encode 720x480 f.i.

For 16:9 mpegs stuff will happen to vertical res as well. Happy calcuputing :)

cheers

[$$$]

Of course you would have to generate different test clips for different target resolutions, just set x and y in my script accordingly.

$

[Wilbert]

Realize that it is different for every TV (how much pixels you won't see) ...

[pacohaas]

very true wilbert, i'm thinking of just making sure there's at least 10 pixels of black on each edge when I do my SVCD's. I've heard people say that most TV's cut off 16.

ulfschack: that's exactly the point, since this file is a 480x480 and svcd's are 480x480, then when I did the test, the pixels were stretched to correctly fit on the tv, the same way they would if I had an svcd, so these measurements work ok for that purpose.

[ulfschack]

Yes, for svcd they would, but I'm just saying (reminding) that it'll change for DVD video, which you will be encoding in the future, s'all.

cheers

[pityu]

Hi,
You are very professionals... but many of us are not.
You know there is ans SVCD test bin/cue image that can be downloaded from the net, you can burn it and test your standalone player. It works well and helps a lot for us (newbies).
Is it possible to find a bin/cue files to download and to burn as svcd to test tv overscan area? As far as I understand you have prepared this kind of svcd. Why dont you make it available for everybody who needs it?
I have Philips TV with a very wide left overscan area but dont know how wide.
Btw is there any way to modify the overscan area of a special TV set?
Is there a service menu hidden that could be used for this purpose?
Service men can do that?
During warranty can you request for changing a TV set with unacceptably big overscan area?
Do you know good links for info about changing overscan?
Many thanks.

[Xenoproctologist]

Generally speaking, a television has approximately 3-5% overscan per side, with 3% being considered optimum. (3% @ 720x480--L/R: 23px T/B: 15px) This is by design--if you decrease the overscan beyond that, you're playing with vomit, as various sources tend to puke all over the edges of the picture. (e.g. VHS flagging/garbage on the bottom; broadcast ntsc horizontal blanking interval bleeding onto the sides)

If your television's overscan is either too large or too small, or the picture is noticably offset to one side, you can consult this site for information on calibrating TV's:
http://www.members.accessus.net/~090/awh/how2adj.html

WARNING: Using this information improperly can severely screw up your television, with results anywhere from botched picture to inability to control basic functions like changing channels and turning the power on and off. You will then have to either (1) pay someone $50/hour to reset your tv to factory defaults, or (2) pay someone $150 to properly calibrate your television. In any case, I assume absolutely no responsibility for what you do with this information, so don't come whining to me if you break anything.

[pityu]

Thank you, I understand. I know its dangerous to manipulate the TV set without background knowledge. The electron beam can be focused in one point for long time and the screen surface can be damaged, & so on. Thank you for being so rapid with the link.
I appreciate it very much.