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question about non-square pixels/HDCAM


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#1 DS Williams

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Posted 02 February 2009 - 03:01 PM

Hey you guys.
I read this over on wikipedia:
"The HDCAM codec uses non-square pixels and as such the recorded 1440×1080 content is upsampled to 1920×1080 on playback."

Now I understand what non-square pixels are, and I know the more horizontal resolution removed during compression, the more rectangular the pixels become..

But my question is, how are non-sqaure pixels used in an NLE, and shows on crt televisions/LCD/Plasmas?

How are they upsampled? Do TVs just cut them in half so they're square again?
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#2 Phil Rhodes

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Posted 02 February 2009 - 04:01 PM

The 1440 width of HDCAM or the 960 width of DVCPRO-HD is never seen outside the electronics of the tape decks - when it comes out the SDI connector, it's been upsampled.

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#3 DS Williams

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Posted 04 February 2009 - 02:49 PM

I understand that but what does upsampling entail?

How do non square pixels become square? Do they just add lines empty line or something?

When editing DVCPRO HD footage on Premiere CS4 I'm editing with 960x720 files in real time. They aren't upsampled, at least to my knowledge. The pixel aspect ratio is 1.33
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#4 Phil Rhodes

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Posted 04 February 2009 - 03:06 PM

> I understand that but what does upsampling entail?

It just blows the image up, exactly as you would in Photoshop (actually, probably not as well as you would in Photoshop).

> When editing DVCPRO HD footage on Premiere CS4 I'm editing with 960x720 files in real time. They aren't upsampled, at
> least to my knowledge. The pixel aspect ratio is 1.33

Yes, the pixel aspect ratio is Premiere's flag to stretch the image out to 16:9.

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#5 DS Williams

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Posted 04 February 2009 - 03:35 PM

But still, HOW does this happen?

What does blowing up the image mean? How does 960 become 1280. I always thought the pixels were just extra wide, because 960x1.33 = 1280

but that's probably not correct is it?
And does premiere ADD redundant pixels so I'm editing a 1280x720 image or are they rectangular non square pixels I'm seeing
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#6 Phil Rhodes

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Posted 04 February 2009 - 03:54 PM

Hi,

Wikipedia explains it better than I can in this article.

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