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Old January 6th, 2009, 02:27 PM   #1
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Render issues - resolution, scaling

I have a project where I imported 1440x1080 AVCHD from my Canon HG20. I am trying to render it to a 800x600 (which is same aspect ratio) mpeg file. When I render, I uncheck the option to create letterbox (since that results in clipping). It appears correctly in the preview as it is rendering, but when I open the file it has black border and the video is skewed (i.e. the aspect is all messed up).

I am sure people have figured out optimal ways to render and get correct results. I am going through lots of trial error and was hoping someone can provide some insight.

thanks,

brian
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Old January 6th, 2009, 02:35 PM   #2
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What kind of mpeg are you creating? Mpeg1, Mpeg2, what? And why choose mpeg? That's a pretty specific (and frankly not that useful) format.
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Old January 6th, 2009, 03:27 PM   #3
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I was just choosing an arbitrary format so I can just confirm the ability to create 800x600 versions of my 1440x1080 AVCHD files. But there seems to be all sorts of video versus display aspect ratio peculiarities.

For instance, when I record HD in 1440x1080 mode and play on my computer (which is set to 1024x768) and then do screen capture, I find the captured image ratio to be around 1.76. So that is my first point of confusion.

If I render to 800x600 and play back and capture, the captured image's aspect is 1.21.

So now I have no idea what represents reality. When I video myself, I want playback to represent true physical properties...

Basically, I just want to render smaller files from Vegas that I can post online and which will a) not stretch my apperance nor contract it...

Also, when I save 800x600 wmv format versus mpg, the displays are different...

What format do you recommend for saving web friendly versions of HD files?

thanks,

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Old January 6th, 2009, 04:02 PM   #4
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These non-square pixel formats are a PITA.


Your computer display and display of HDTV both use square pixels.

SDTV in the US or NTSC countries uses 720x480 non-square pixels. (PAR = .9091)
In Square pixels, NTSC = 655x480.

So if you plan to render for the web or other computer based output, or HDTV, render square pixels.

The two primary HD formats are 1920x1080 and 1280x720, both square pixel formats. HDV cameras can't squeeze 1920 pixels onto the tape, so they use 1440 instead and make them non-square. So on playback when the software realizes it's HDV it unsqueezes it and stretches it to fit a 1920 space.

You can simply things a LOT by getting all your work into square pixel space. From there, going to web, HDTV, or SDTV is trivial and you don't have all these wacky conversions messing everything up.

SDTV (NTSC) = 720x480 or 1.33:1 (or 4:3)
Computer = 1024x768 / 800x600 = 1.33:1
HDTV = 1920x1080 or 1280x720 = 1.78:1 (or 16:9)
Academy Format = 1920x1038 / 1280x692 or 1.85:1
Scope = 1920x800 / 1280x532 or 2.39:1(2.40:1)


Does that help?
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Old January 6th, 2009, 04:05 PM   #5
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Quote:
Originally Posted by Brian Huether View Post
I was just choosing an arbitrary format so I can just confirm the ability to create 800x600 versions of my 1440x1080 AVCHD files. But there seems to be all sorts of video versus display aspect ratio peculiarities.
You screwed up from the start.

1440x1080 is really squeezed 1920x1080 or a 16:9 format. Your 800x600 is a 4:3 format, so you've shot yourself in the foot from the beginning.

Render out your 1440x1080 (non-square) to a square pixel 16:9 format and you won't change the looks of anything and you can create smaller files. Cutting the size in half is a good place to start. Say 960x540.
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Old January 6th, 2009, 04:24 PM   #6
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Ahhhhh, ok this makes sense. Yes - I definitely shot myself in the foot! Good thing I am just testing!

thanks,

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Old January 6th, 2009, 05:05 PM   #7
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I got it to work but now it doesn't play correctly in youtube... Looks fine in Media Player. Any idea what might be going on?

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Old January 6th, 2009, 05:09 PM   #8
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Got "what" to work?

Send me a link to the youtube
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Old January 6th, 2009, 09:08 PM   #9
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Here is the youtube:

YouTube - Guitar Lessons - Minor and Pentatonic Minor Scales

All I did was uploads that same mpeg that I posted a link for...

thanks,
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Old January 6th, 2009, 09:20 PM   #10
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What's wrong with it? Looks fine to me.
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Old January 6th, 2009, 09:40 PM   #11
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You don't notice the black bars to the left and right? The viewable video is scrunched together compared to playback in WMP. THe WMP plays at the correct aspect.
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Old January 6th, 2009, 09:46 PM   #12
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Quote:
Originally Posted by Brian Huether View Post
You don't notice the black bars to the left and right? The viewable video is scrunched together compared to playback in WMP. THe WMP plays at the correct aspect.
WMP understands non-square pixels. VImeo, Youtube, Exposure Room, and others do not.

Encode the video at 1280x720 square pixels and upload. You'll see the difference right away.
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Old January 6th, 2009, 10:34 PM   #13
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Strangely enough though, youtube displays my video thumbnail with what appears correct aspect...
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