One more time for the idiot -- ME!

CaptainMench

CaptainMench

Carbonite Member
Sorry --

What is DVX's 16:9??

720x405? or 853x480

I made a widescreen dvd in anamorphic mode and it comes up wider than my normal 720x480 ones when played by my computer dvd program (apple).

That's the first question.

Second...

Screen grabs - so if I bring an anamorphic out of FCP and into Photoshop to resize (I use 720x405 only because that's what I though... see question 1). Do I still need to squeeze it something more because of square v. rectangle pixels?

Am I thinking too much?

Thanks.

CaptM
 
Re: One more time for the idiot -- ME!

square pixel dimension is 864 x 480.. photoshop CS has pixel aspect ratio so you can leave at 720x 480 with 1.2 pixel aspect

720 pixels shown at 1.2 pixel aspect means each pixel is shown at 1.2 times a normal square pixel width, so to get the same width from regular sqaure pixels you have to have 864 pixels. 720 times 1.2 = 864  to get 864 x 480  ..it is not a true mathematical 16:9 .    but DV 720 x 480 isnt true mathematical 4:3 either. regular 4:3 DV uses .9 pixel aspect so the pixels are thinner than a sqaure pixel cause they are only .9 of a square pixel width. so in square pixels a 4:3 DV frame is 648 x 480 .. this is also not true 4:3 .     the reason its a little off is because DV drops 6 vertical pixels from full D1 SD resolution which is 720 x 486. so full D1   16:9 in square pixels  is 864 x 486  that IS true mathematical 16:9 and full res D1 4:3 in square pixels is 648 x 486 and that is true mathematical 4:3 .   the only thing you change for DV is drop the 6 pixels from the height. the DV compression drops the 6 extra pixels off to have better and cleaner compression.  



you cant make the height shorter, and keep the width the same. the pixels are still 1.2 times width, and you still have a 864 square pixel wide image. , and the height is unaffected by the width calculations so it stays 480. and you cant shorten the width to 853 make it mathematically correct 16:9  with 853 x 480, because 720 times the 1.2 pixel aspect will only give you 864, and the 480 is the mathematically incorrect number to begin with .. the hieght is not mathematically correct.. not the width..so you shouldnt accomodate the mathematically incorrect hieght by changing the width  to match mathematically.  
so correct 16:9 in DV is 864 x 480   its NOT excactly right mathematically, but again neither is 4:3 DV.. its just 6 pixels to short in the height. and thats how its supposed to be so that the DV compression works well.

so again in clear terms 16:9 DV in square pixels is 864 x 480. no other figure is correct. (but 864 x 486 would be acceptable visibly if your importing something from full D1 res)

hope this helps explain it.  ;)
 
Re: One more time for the idiot -- ME!

[quote author=CaptainMench link=board=Clips;num=1097818519;start=0#0 date=10/14/04 at 22:35:19]Sorry --

What is DVX's 16:9??  

720x405? or 853x480
[/quote]
It's 720 x 480.

If you're talking about taking it to a computer program for manipulation, or displaying on a computer, then you have to convert to square pixels for proper display (as IAL said).

But if you're keeping in the video realm, authoring a DVD, etc., then you should understand that the 16:9 image is made up of a pixel array of 720 x 480. Those pixels are interpreted to be 1.2x as wide as they are tall, but that's done by the television, not by changing the frame size. The frame size stays 720 x 480.
 
Re: One more time for the idiot -- ME!

WOW -- that's nuts. Who thought of THAT???

Thanks for the info, though.

I'm not going to worry my poor head ever again about this.

Really -- thanks.

CaptM
 
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