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Old June 22nd, 2008, 02:15 PM   #1
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Aspect/Pixel ratios & Flash

I'm a newbie and I've tried to wrap my mind around all this aspect ratio and pixel ratio stuff, but am still confused to some extent.

In particular, this relationship between native in 720 x 480, and 640 x 480.

I'm shooting with Canon XH-A1 (still in Standard Definition Mode while learning)
Capture and editing on Windows w/Adobe Premiere Pro CS3
Wanting to publish my video in Flash format on my website

When my cam is set to shoot - and my PC captures - SD 4:3 720 x 480 it looks great on the screen. Exporting to MS AVI similarly plays back great in Windows Media Player. And, timeline still frame captures create .tiff files that display in another separate image viewer program great, and which lists these stills as being 720 x 480. So far so good, except I'm confused that 720 x 480, mathematically, is NOT 4:3 but rather something like 4.5:3.

So, anyway, I want to render my video into Flash format for my website. Somewhere, some "expert" on Flash on the Adobe site says that you're supposed to render this 720 x 480 out to 640 x 480 Flash, not 720 x 480 because of how computer monitors work or something. But my Flash rendering comes out looking squashed (as I would expect). But supposedly it should look right on my computer screen at 640 x 480? Shouldn't I just be rendering out to Flash at the same 720 x 480 for offering on my website at this full native resolution?

Obviously, I'm looking at both the original captured 720 x 480 on the same monitor as the rendered Flash version and it's definitely squashed at 640 x 480.

So why this talk about 640 x 480, when exporting my 720 x 480 to it squashes it in width, apparently by this difference?

I just need the simple explanation of what is probably the obvious here, but I'm still confused about. Do I indeed just render out to 720 x 480 in Flash and be happy, or am I violating some rule I still don't understand.

Finally...if I wish to create a version at a smaller resolution can I just apply the same ratio of 4.5:3 (720 x 480) and cut it in half to 360 x 240, which of course also isn't exactly 4:3.

The "expert" on Flash also says something about it being best to render to other resolutions that are equally divisible by 16, which both 720 and 480 are, but which 360 isn't. Is this something else I need to consider, because that complicates this aspect ration thing even further it seems.

I appreciate anyone willing to give me short and sweet on this.

Thanks in advance.
Cliff
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Old June 22nd, 2008, 02:27 PM   #2
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Flash uses square pixels. So 640x480 would be 4:3. 720x405 would be 16:9.

I'd recommend doing a search and reading up on Pixel Aspect Ratios so you can get a good understanding of all that fun stuff.
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Old June 22nd, 2008, 02:46 PM   #3
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Quote:
Originally Posted by Douglas Thigpen View Post
Flash uses square pixels. So 640x480 would be 4:3. 720x405 would be 16:9.

I'd recommend doing a search and reading up on Pixel Aspect Ratios so you can get a good understanding of all that fun stuff.
I've done the searching and reading, before I made my post, but was still confused on my specific application I referred to, which is why I asked for help here.

While I certainly appreciate your response, it didn't answer my specific questions and only seems to confirm what I already stated.

Thanks anyway for taking the time to respond.
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Old July 10th, 2008, 09:30 AM   #4
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The key here is the difference in the Pixel Aspect Ratio (PAR).

The reason you don't use the 720 x 480 native resolution when exporting to flash is because those native pixels have a 0.9:1(non-square) PAR rather than a 1:1 PAR like pixels on a computer monitor. When converting to square pixels for correct 4:3 display on computer monitors, 720 x 534 (scaled up slightly) or 640 x 480 (scaled down slightly) are used.

These articles helped me understand this a little better:
http://www.artbeats.com/assets/artic...ct_ratio_1.pdf
http://www.artbeats.com/assets/artic...ct_ratio_2.pdf
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Old July 20th, 2008, 10:11 AM   #5
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Originally Posted by Brian Rossen View Post
The key here is the difference in the Pixel Aspect Ratio (PAR).

...

These articles helped me understand this a little better:
http://www.artbeats.com/assets/artic...ct_ratio_1.pdf
http://www.artbeats.com/assets/artic...ct_ratio_2.pdf
Brian. Thank you very much for the informative links!
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