KVR Audio

chagzuki · Post by **chagzuki** » Tue Aug 16, 2005 3:06 pm

Pal is 720 x 576.

Where/when is 768 used?

whyterabbyt · Post by **whyterabbyt** » Tue Aug 16, 2005 4:24 pm

overscan

Kriminal · Post by **Kriminal** » Tue Aug 16, 2005 4:27 pm

i though only NTSC overscanned, and that was on the width?

whyterabbyt · Post by **whyterabbyt** » Tue Aug 16, 2005 4:29 pm

There's usually overscan on anything intended for TV. And 720/768 is the width.

Kriminal · Post by **Kriminal** » Tue Aug 16, 2005 4:33 pm

whyterabbyt wrote:There's usually overscan on anything intended for TV. And 720/768 is the width.

Yeah i know, i meant it only overscans on the width...so my geek mate told me. No idea why i still know that, or even if its true

zed · Post by **zed** » Tue Aug 16, 2005 4:47 pm

PAL is 768x576 => device aspect ratio of 1.333..
TV displays rectangle pixels of size 1.06666x1, so to keep a circle a circle you have to send a digital signal of 768/1.06666 x 576 to the screen => 720x576.
Computers should only work with square pixels (768x576)
NTSC screen supposes the pixel to be 1x0.9 size

chagzuki · Post by **chagzuki** » Tue Aug 16, 2005 6:49 pm

I get you zed. You're saying it's not about overscan, just pixel aspect ration conversion.
So is overscan an issue? If dvd format is 720, there is no overscan.

munchkin · Post by **munchkin** » Tue Aug 16, 2005 7:07 pm

...tumbleweed blows by...

...paint dries...

chagzuki · Post by **chagzuki** » Tue Aug 16, 2005 7:16 pm

I thought overscan was this:

http://www.geocities.com/ResearchTriang ... rscan.html

BONES · Post by **BONES** » Wed Aug 17, 2005 12:16 am

It is indeed pixel aspect ratio. PAL D1 pixels are wider than square so when you are looking at them on a PC with square pixels you need to add in a few extra to keep it looking right. 768x576 are the square pixel dimensions for PAL, 720x576 are the PAL D1 pixel dimensions. Plus, of course, PAL D1 pixels are a very different shape to NTSC D1 pixels, which are narrower than square.

SaviorNeeded · Post by **SaviorNeeded** » Wed Aug 17, 2005 12:23 am

oh, that life were always this simple.

Tom

chagzuki · Post by **chagzuki** » Wed Aug 17, 2005 12:38 am

So, if one is creating a movie for both widescreen format and standard PAL, what's an optimum resolution to work at without editing at an ultra-high resolution?

At 1024 x 576, 16/9 you can cut the sides off and end up with 720 x 576 without resampling the image, which seems like a good idea.

Hang on, not sure I've done my maths right. . .

chagzuki · Post by **chagzuki** » Wed Aug 17, 2005 12:40 am

Nope, that can be trimmed to 768 x 576. . .

chagzuki · Post by **chagzuki** » Wed Aug 17, 2005 12:47 am

It would be 960 x 576 - device aspect 16/9, pixel aspect 1.067

Does that make sense? It's too late in the evening to be doing this shit.

DVD formats - where does 768 x 576 come from?