Proper Video NTSC 4:3 Aspect Ratio

karmatized · #1 (**permalink**) 12-31-2005, 02:16 PM

Just something im experimenting with but i dont think 0.900 is actually the right pixel aspect ratio, for ntsc, even though all the software uses it to encode to i think the correct aspect is 0.889

0.889 = 1.33:1
while 0.900 = 1.35:1

1:33:1 is the correct aspect, so u tell me, why the DVD Commision decided to use a mathimetecly incorrect aspect. Perhaps its the old saying "Close Enough" and 0.900 looks nicer on paper then 0.889

But yeah just thought id shoot that out there that 0.889 is actually the correct aspect ratio for 4:3 video

720 x 480 = 0.889
720 x 486 = 0.900

Only reason i know this is by doing the researching because i do 3d work In maya and various other programs, And that is the correct calculation.

So next time you output your file before you save to mpeg change either if you want the proper represintation of the image

You could easly resize your image to 720 x 486 and convert to mpeg. This would at least hold make sure the proper aspect shows

karmatized · #2 (**permalink**) 12-31-2005, 02:17 PM

Oh yeah pal has a similar formula but i havent checked on that one yet

karmatized · #3 (**permalink**) 12-31-2005, 02:28 PM

ahh here we are
http://help.bccc.com/manuals/maya/Us...obalAtts5.html

This is a chart of most resolutions and aspect ratio's and what they need to be to get the correct aspect ratio.

like i said 720 x 486 for ntsc at 0.900 aspect, so get to resizing your video's before you encode

Marc Peters · #4 (**permalink**) 12-31-2005, 02:45 PM

Just to clarify so that those with DV cameras don't think they're doing something wrong: 720 x 480 at 30 fps is the standard frame size for NTSC miniDV, whilst 720 x 486 is the broadcast frame size for NTSC. Although you're obviously losing something, the area "lost" is not noticable as this area is well outside the "safe" margin.

karmatized · #5 (**permalink**) 12-31-2005, 03:19 PM

there is no safe margin with aspect ratio, If your not resizing to 720 x 486 the video is stretching, It may not be too noticable but it is there, If its a home video then screw it, but if your doing something where a great deal of money is involved u should do it perfect. Dont get lazy with something so simple.

AGAIN IM SPEAKING OF NTSC ONLY, PAL IS OK.

Also As for the DV camera thing, yeah your files should be fine as they are, as the camera is recording at the correct aspect ratio in it self, so its making that correction.

But for any video's gotten elsewhere that are squarepixels This math does apply. That is the proper framesize for correct aspect.

Marc Peters · #6 (**permalink**) 12-31-2005, 03:57 PM

The world of video is dictated by standards, most of which you never really need consider. You've hit a stumbling block that's specific to creating original animated content. Essentially "you" are the camera and need to make a decision on how you're going to record your footage.

Given that this is a video editing forums, the majority of NTSC-land readers will be used to seeing the familiar 720 x 480 frame size from their NTSC DV Cameras. This is a standard and NTSC DV users need not worry about their frame size / aspect ratio (10:11 or 0.909 for 4:3) as it has been dictated as part of the standard.

I'm not in the industry and therefore do not need, nor have the inclination, to know the technicalities. Suffice to say that source footage from an NTSC DV camcorder does not need to be adjusted to play back correctly as MPEG2 on a TV: 16 pixels of the 720 x 480 are overscanned on the TV, so that the actual display is 704 x 480. 704 x 0.909 is 640, giving a frame size of 640 x 480, which is 4:3.

karmatized · #7 (**permalink**) 12-31-2005, 04:01 PM

bah its a complicated mess, lol, im stressing my self out with all these damn calculations.

Bah Bah Bah, ionno. lol

Not saying that everyone should do it, just something i noticed guys, its too early for me , im tired. lol

Marc is right for the most part. It is broadcast NTSC So this really would apply specially for anyone doing broadcast material.

I think im just annoyed at the fact that our Aspect math is messed up by 6 pixels. lol

karmatized · #8 (**permalink**) 12-31-2005, 04:42 PM

ok mark you got me, for video editing that is, though my frame size is exactly what i need for my animation it does not ness work for reg video editing....

http://www.uwasa.fi/~f76998/video/conversion/

That site is a super in depth how to / know it all when it comes to this stuff from TV freq and everything relating to aspect ratio. Its a good read, A Long one But very educational. Anyone wondering what we are talking about should check it out....

Crusty · #9 (**permalink**) 12-31-2005, 08:50 PM

Heh.. for animation and stills I always use 640x480 and then let the editing software warp it into 720x480. By the time it hits the TV screen it's back to 4:3 and circles remain circles.

karmatized · #10 (**permalink**) 12-31-2005, 10:17 PM

only reason i dont do that, is with all the work i put into the 3d work, im not trying to loose any resolution, or at least keep it to a minimum