Why are PAL snapshots 786x576?

Marco. wrote on 4/24/2005, 3:35 PM
I know about the pixel aspect ratio backgrounds but ...

... if having a PAL project with PAL DV footage and having the internal preview set to Best (Full) I would await the "Save Snapshot to File" function would output 787x576 - not 786x576 (786x576 is what it is in any Vegas version).

Is there a reason why this output differs by one pixel of horizontal resolution?

Bad thing about it is it will be bit unsharp after being reimported. Having a 787x576 output could avoid the loss.

Marco

Comments

Chienworks wrote on 4/24/2005, 3:49 PM
The actual size would be 786.672x576, so it's inbetween 786 and 787. I suspect that the SONY engineers merely rounded to the nearest even number. They did the same thing with NTSC where the size should have been 654.545454... and use 654 instead.
Marco. wrote on 4/24/2005, 4:05 PM
Thanks for the input. If they just did a mathematical rounding (what actually might be a reason) they maybe missed to make a "real live test". ;-)

The bad effect is 786x576 is bit unsharp after reimport and a small black border of half a pixel size is added on left and right side. Taking same reimported pic and doing whole process once again ends in having a one pixel border left and right side. After 4 processes it's a two pixel border on both sides and so on. And each time it becomes more blurry.

Imported pics of 787x576 are perfect - no borders and them are sharp.

So if Vegas expects 787x576 for import - wouldn't it be just correct to make the output same size? - Maybe this is an easy fix.

Marco
Chienworks wrote on 4/24/2005, 5:54 PM
Part of the blurriness could also come from the fact that Vegas will scale the 786/7 x 576 image to 720, then rescale the 720 to 786 when saving the snapshot. So every pass through involves two rescalings even if you used 786.6whatever.

Why are you running the pictures through so many cycles? Can't you come up with a workflow that avoids that?
Marco. wrote on 4/25/2005, 1:33 AM
>> Part of the blurriness could also come from the fact that Vegas will scale the 786/7 x 576 image
>> to 720, then rescale the 720 to 786 when saving the snapshot

The blurriness is visible directly after reimport. There is no rescaling to 786 then (for the preview it is rescaled to 787x576 if it's set to "Simulate Device Aspect Ratio"). There is no blurriness if a 787 format is imported. And taking a look at what the size of the preview window is when it's set to Best (Full) and "Simulate Device Aspect Ratio": 787x576.

>> Why are you running the pictures through so many cycles?

This was only for a test. The sharpness loss is visible after the first cycle. Taking a closer look also presents the black borders. Doing several cycles shows that each process encreases the size of the border at one more pixel.

So this test stated that the way Vegas exports snapshots and the way it imports snapshots differs by one frame.

Marco
Marco. wrote on 4/25/2005, 3:01 AM
>> does your version of Vegas 6 have a help file for portals transtion

If you mean the help file which opens when clicking the quotation mark in the Event FX window: Yes.

>> or separate help files for legacy broadcast colors filter

A separate help file? - No. At least I didn't find one.

>> and the newer broadcast colors filter

No. I wasn't aware there should be a new broadcast color filter. Mine's still the old one.

My latest version is V6 build 99. But if this should relate to the snapshot thing - this happens with any Vegas version, even with version 4 (and probably 3 too).