Comments

swarrine wrote on 4/26/2002, 7:40 AM
Both are correct (I think).

VV3 keeps the 480 constant (720 x 480). In order to adjust a square to rectangular it would be 720 X .9092 = 654.62 (rounded to 655) thus VV3 uses 655 X 480 for stills.

Premiere keeps the 720 constant (720 x 480). In order to adjust a square to rectangular it would be 480 X 1.125 = 540 thus Premiere uses 720 X 540 for stills.

My disclaimer: This issue is confusing and I could have it completely wrong... Since no one else took a stab at it for a couple of days, I thought I would. I welcome any corrections.
SonyEPM wrote on 4/26/2002, 8:26 AM
Adobe stretches imported stills vertically, and Vegas stretches horizontally. Both are legit options, and the stretch method accounts for the different recommended still sizes.

We believe it is incorrect to stretch vertically- has anybody seen what happens if you vertically stretch/squash interlaced stills, from say a 3D package? In Vegas you can use either 720x540 or 654x480, but we advise using the latter whenever possible.
Mir wrote on 4/26/2002, 10:41 AM
Hi,
my problem is not to import still image; is about why VV3 use another number definition for the pixel aspect ratio.
Here I copy a old post by JON, that I finded in your forum, and my opinion that i give him the last week; but nobody reply me.

Please give me an answer!!
thanks
Mir


-----old post by Jon---------------------------begin--------------------------------
I have a question regarding Vegas Video.

Vegas lists the Pixel Aspect Ratio for standard NTSC DV as 0.9091 and Widescreen as 1.2121, and PAL Standard as 1.0926 and Widescreen as 1.4568

By my calculations, these have an error of roughly +.02%
The 4 aspect ratios mentioned above should be 0.889 1.1852 1.0667 1.4222

The way I calulate this is as follows:

(src_pixel_h / display_h) / (src_pixel_w / display_w)

(480 / 3) / (720 / 4) = 0.8889 (4:3 NTSC DV)
(480 / 9) / (720 / 16) = 1.1852 (16:9 NTSC DV)
(576 / 3) / (720 / 3) = 1.0667 (4:3 PAL DV)
(576 / 9) / (720 / 16) = 1.4222 (16:9 NTSC DV)

Vegas' numbers are +.0227% off for NTSC, and +.0243125% off for PAL

I send the question to make sure that Vegas is accurate in adjusting the aspect ratio of imported clips/stills. (or that I am accurate in calculating the correct AR for clips I import)

Is this a bug or is my math/logic faulty? I know that this is the type of bug that easily slips by, as it's 'close enough' to go unnoticed.

The source file resolutions that would be needed for vegas' aspects to be accurate are:
NTSC DV (Both standard & widescreen) - 704x480 or 720x491
PAL DV (Both standard & widescreen) - 703x480 or 720x590

704x480 is an MJPEG format, or D1 or double the NTSC VCD dimensions. Maybe this was the source of the error.

It's important that vegas is (or I am) accurate.

Can you please let me know what you think?

Thanks!

- Jon
--------------------------------------------end-------------------------------------



---------------my-answer-------------begin-------------------------------------------

http://www.mir.com/DMG/aspect.html
http://toolbox.sgi.com/TasteOfDT/documents/video/lurker/pixelaspect.html

In this document is 2 doc is the response of pixel aspect ratio question.(the calculation error is from the begin, some use pixel frame ratio and other use analog scan line from they derive the pixel)

But someone is still in wrong.
I mean, I use many video program combustion,after effect,premiere ecc... and ALL use the standard description of pixel aspect ratio (D1/NTSC DV 0.9- D1/NTSC DV wide 1.2- D1/PAL DV 1.067- D1/PAL DV wide 1.422,..)
VV3 use another(it is correct, but is another description).
Someone must change to conform to the other or you must make a sort of BLU BOOK of rule for pixel aspect ratio description for all the user that con not understand this complicate math rules.

This is a step to simplify the life for all the user.

tanks

MIR

----------------------------------------------end-answer-----------------------------
SonyDennis wrote on 4/28/2002, 10:39 AM
The reason those calculations may not be right is because the 4:3 frame aspect ration is NOT defined by the pixel count of the rendered image. For example, digital video with 704 AND 720 horizontal pixels both have the same 601-defined timing, so therefore they have the sample pixel aspect ratio! They are just cropped differently. The Vegas team calculated their pixel aspect ratios based on the pixel clock STANDARDS for digital video. If you have STANDARDS which show them to be wrong, please reference them.
///d@