the six pixels that changed my life

[Walter Soyka]

[Dave Fleming] “It’s just annoying to have several extra steps in the AE process now…1) Interpreting the footage lower field first–which is just bizarre because when I wasn’t using the Avid DV codec it knew the footage was 720 x 480, 1.21, lower field first, but now exporting with the Avid DV codec it forgets to separate fields! and 2) Telling AE that the footage is D1 WS 1.21 and not .91”

After Effects uses a set of rules stored in a text file to interpret footage.

If you want to globally change how After Effects interprets specific file types (based on frame size, frame rate, container type, and codec), you can edit the interpretation rules.txt file. See Interpret footage items [link] in the manual for more.

It looks a little daunting at first, but the explanation in the comments section of interpretation rules.txt is pretty well-written. Just make sure you make a backup copy of your original interpretation rules.txt in case something goes wrong!

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Jason Brown]

I’m sure you know this but CMD+alt+C remembers interpretation and you can paste the interpretation to multiple clips at one time in your project window. (CMD+alt+V).

This was always helpful when going from AVID to AE…the necessary metadata that Adobe puts in QT exports from Premier apparently doesn’t exist when coming from AVID.

-Jason

ALSO…you said –

[Dave Fleming] “Interpreting the footage lower field first”

It’s been a while since I dealt with interlaced footage in AE, but the interpretation of which field is first isn’t controllable, only to “separate fields”…if selected, this will essentially de-interlace your footage so you can scale it above or below 100% and not have a strange field rendering. Please correct me if I’m wrong.

[Gary Hazen]

[Jason Brown] ” Please correct me if I’m wrong.
“
You’re wrong. You can set the interpretation to lower field first or upper field first.

[Jason Brown]

It’s funny…because until now, I never fully understood what that function did. I always assumed that it deinterlaced the footage, but after reading AFX help…now I have a question.

Quoted from Adobe help site on AFX CS4:

…in an After Effects project, you get the best results if you separate the video fields when you import the footage. After Effects separates video fields by creating a full frame from each field,… (IT GOES ON TO SAY) …After Effects accurately converts the two interlaced frames in the video to noninterlaced frames, while preserving the maximum amount of image quality.

So now I’d like to ask, if AFX creates a “full frame from each field” … wouldn’t the duration of the clip double?

Sorry to be a little off topic 🙂

-Jason

[Dave Fleming]

Thanks for the tip on the interpretation rules file, Walter. I will edit the rules for the Avid DV codec since I’ll be dealing with quite a lot of this footage.

Happy Holidays to one and all and thanks again for the help!

Dave

[Walter Soyka]

[Jason Brown] “So now I’d like to ask, if AFX creates a “full frame from each field” … wouldn’t the duration of the clip double?”

Sort of. After Effects knows the difference between a field and a frame. If you have interlaced NTSC footage and separate the fields, then open the footage in a viewer, you’ll be able to step through it by field instead of by frame.

There’s no such thing as an interlaced comp per se, so the footage will still behave as a 29.97 fps clip in a 29.97 comp — but it’s still critical to separate the fields properly so that transformations and effects will not improperly cross fields. To get interlaced output, you must use field rendering.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Jason Brown]

I did not know this…great read Walter, thank you so much.

I had always done “separate fields” and I thought I knew what the software was doing…apparently I was wrong 🙂

Have a great Christmas …

-Jason