Pixel Aspect Ratio (PAR) Tutorial

:::going bald from ripping hair out:::

I'm sure this is easier than I'm making out to be. I SEEM to understand a little more now, but I can't figure out how to change my AE comp. setting to work with this. I don't see how to give it a PAR of 1.78. If this is very common, why isn't this an option?
 
1.78 isn't PAR, it's the aspect ratio (16/9 = 1.78). The Pixel Aspect Ratio depends on the codec. If it's HDV, the PAR is 1.33. If DV, it's 1.2 for widescreen and .9 for fullscreen. Once you added the item to the render queue, there is a Render Setting menu that shoud let you set the PAR. It's important to note that if you're planning on editing the footage after, you need to render it with its original PAR or you might run into problems with your NLE project setting later.

What resolution and codec are you working with?
 
here's my settings:
Picture2-1.png


here's what it makes:
Picture3.png


With both selected as widescreen, and 1.21 PAR, shouldn't it NOT be 4:3? I feel so dumb for not understanding this. I've never made a WS project before, and I didn't think it would be a problem.
 
Ok, I unchecked "Lock aspect ratio" and tried the 720 / 405 and that did it. It changed the 3:2 (1.5) to 153:86 (1.78)

So why did I have to do that if I created it as a Widescreen? Shouldn't that be automatic? I don't understand
 
720 x 480 PAR 1.2 is widescreen, except the pixel isn't square. Most media player can interpret between square and non square pixel to gives the correct look. Anamorphic pixel displayed in square pixel mode will look squeezed, but it is still widescreen.

PAR is used as a compression tool, where you vary the ratio of the pixel height and width (NOT the pictures') to keep the data rate down. It really just depends on your final output. For web, it's best to just keep it square pixel and render at the appropriate resolution. For post, all NLE can properly interpret anamorphic pixel to give the correct result.
 
Lol, I would except that that's pretty much it as far as theory. It's a bit confusing at first but once you understand it it's the simplest thing in the world.
 
Huy Vu said:
PAR. SD 16:9 has a PAR of 1.2; SD 4:3 has a PAR of .9.
Click to expand...
This is true for AE CS3 and all versions prior to CS3. However Adobe made some changes to correct the PAR's with version CS4.

The new PARs:
DV/D1 NTSC is now .91
DV/D1 NTSC widescreen is now 1.21

Why did Adobe change the PARs ?
To make a long story short, many years ago when the engineers decided on the PAR ratio's the math wasn't as exact as it should have been. Engineers rounding off, who would have thunk it? Nobody seemed to notice or care about the minor detail and all was well with the world, the pars of .9 and 1.2 were seemingly set in stone. Then back in the late 1990's the industry (Apple and others) realized that the math for calculating the PARs wasn't correct. The problem was that every company in the industry (Avid, Apple, Autodesk, Grass Valley, etc.) had been using the .9 and 1.2 ratio's for decades - making a change to the numbers would rock the boat so to speak. It was decided to keep using the erroneous numbers because after all it was the standard that everyone was accustomed to using. This went on for nearly a decade. Then the engineers at BBC couldn't take it anymore and they pestered Adobe about correcting the math. Eventually Adobe succumbed to the BBC's persistent demands and corrected the math and the PARs in AE CS4.

For the record Chris Meyers shared this information at NAB this year, I'm simply paraphrasing. Also worth noting, the PARs for PAL video have also changed - I excluded them to keep the story short. As with color management Adobe is a pioneer in the industry, the first company to have the correct PARs. I guess we'll have to wait and see if others follow suit. The good news is that HD is square pixels.

Here are some additional resources on the subject:

http://help.adobe.com/en_US/AfterEffects/9.0/WS3878526689cb91655866c1103906c6dea-7f3aa.html

http://www.lurkertech.com/lg/video-systems/#pixelaspect
 
even though the info is here it seem better to have on disc do we can rewind over and over and see examples. What about a vimeo or youtube video? :) having it all in one place would be good.
 
that video would reach a million hits by me alone.

After reading this thread, I'm looking at my computer screen the same way the youth in my youth group used to look at me after a sermon.
 
if you have a paypal option i would send you a donation for a burn to disc and mail delivery.. just a thought.
 
cool. although a burned disc will last longer than an on site web site hosting videos. At least until the plug is pulled on either end. many thanks..
 
Huy Vu said:
h.264 is just about the most efficient compression codec available today, I use it exclusively. My general workflow is: export uncompress, load Quicktime Pro, use bitrate from 1500-1800 kbs for SD video, and 2000-2500 kbs for HD video and make sure that the audio codec is AAC. Multi-pass render for h.264 can take a while with longer video so I don't use it unless size is really important.
Click to expand...

Please help me understand something. CS4 comes from the factory with the H.264 codec. Why should I buy QTPRO to get the H.264 codec?

thx
 
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