New comp – DVCProHD 720-4:3 aspect preview

[Joey Foreman]

Not sure whose fault it is, Apple’s or Adobe’s – probably Adobe’s – but AE still doesn’t correctly handle DVCPro footage when creating a new comp.
Here’s the fix :
Create a 1280×720 square pixel comp, 23.976 fps, then drop your footage into it. Of course you’ll need to augment the comp duration to accommodate your clip.

[Darby Edelen]

Do you have pixel aspect ratio correction turned on? DVCPRO HD and HDV both use non-square pixels.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Joey Foreman]

No pixel aspect creation. It just works. If the shot is going back to FCP, though, it will have to rendered nonsquare.

[Darby Edelen]

[Joey Foreman] “No pixel aspect creation. It just works.”

I’m not quite clear on what that means.

DVCPRO HD and HDV both use non-square pixels, which is why the comp presets for those formats in AE use non-square pixels, and if a comp is using non-square pixels and you don’t have pixel aspect ratio correction turned on in the comp preview it will appear squished/stretched.

I was asking whether the OP had pixel aspect ratio correction on or off in their comp (it should be on). You are correct in that AE should properly interpret the footage on import with the proper pixel aspect ratio and that footage can then be placed in any composition with any pixel aspect ratio (including square) and it will look correct, but I don’t think the poster needs to go through that process, I think it is just a matter of turning pixel aspect ratio correction on.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Joey Foreman]

Hmm. okay. I tested that and you’re right. What’s weird, though, is that this has only been an issue since AE 7.
AE 6.5 correctly interprets the footage on import as 1280 x 720, Square Pixels, and requires no correction
CS3 imports & interprets the same footage as 960 x 720, 1.33 p.a.r. and requires correction.
Why do you suppose that is?

[Darby Edelen]

[Joey Foreman] “AE 6.5 correctly interprets the footage on import as 1280 x 720, Square Pixels, and requires no correction CS3 imports & interprets the same footage as 960 x 720, 1.33 p.a.r. and requires correction.
Why do you suppose that is?”

I’m not sure, but if you look up DVCPRO HD, HDV (square for 720, non-square for 1080) and HDCAM, they do use non-square pixels. So technically, AE 6.5 is incorrect. It is probably related to AE 6.5 being a few years old and not knowing how to interpret the latest formats on import.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Joey Foreman]

You’re right that these formats are non-square. The issue, though, is why AE incorrectly displays this footage by default when creating a new comp. DV NTSC is also non-square, yet requires no pixel aspect correction.
My understanding of pixel aspect correction is that it is used when creating round graphics in a square pixel comp so that they will display correctly when rendering to a non-square format – not so that AE will correctly display non-square footage in a non-square comp.

[Darby Edelen]

[Joey Foreman] “DV NTSC is also non-square, yet requires no pixel aspect correction.
My understanding of pixel aspect correction is that it is used when creating round graphics in a square pixel comp so that they will display correctly when rendering to a non-square format – not so that AE will correctly display non-square footage in a non-square comp.”

NTSC DV does require pixel aspect ratio correction.

There are two points at which a pixel aspect ratio can come into play:

1) At the footage level
2) At the composition level

If you have non-square footage and it is interpreted with the correct pixel aspect ratio, then it will appear correct in a square pixel composition because AE knows to adjust for the PAR of the footage. Alternatively, if you put this footage into a non-square composition AE will display it correctly relative to the composition’s PAR. More on this below.

If you have non-square or square footage (or any footage) and you place it into a non-square composition, you have the option of viewing that composition with pixel aspect ratio correction off or on (Note: this is different from the footage’s pixel aspect ratio correction which happens separately when you or AE interprets the footage).

If you choose ‘off’ in a composition with a non-square PAR then the footage will look squished (if the comp has a PAR > 1) or stretched (if the comp has a PAR < 1) because AE is displaying the non-square pixels as square pixels (your computer display uses square pixels). If you choose 'on' then AE squishes or stretches the footage in the opposite direction, for display only, to match the PAR of the composition/device/format so that the footage will look ‘correct’ (although this process of stretching/squishing can introduce vertical display anomalies, this is only because AE is stretching the footage and not resampling it… they do not appear in renders).

I suggest you read up more on PAR in the AE user manual. I’ve also posted on this in the past in a more straightforward way:

https://forums.creativecow.net/readpost/2/929839

=)

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Joey Foreman]

Okay, i’ll read up on it. I’m still confused as to why NTSC footage is displayed in the composition window with Pixel Aspect Correction off. If you turn it on it stretches the footage out.
Why is the case with NTSC but not DVCPro?

[Darby Edelen]

[Joey Foreman] “I’m still confused as to why NTSC footage is displayed in the composition window with Pixel Aspect Correction off. If you turn it on it stretches the footage out. “

How is the footage interpreted? What are the composition settings?

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA