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the six pixels that changed my life

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Dave Fleming
the six pixels that changed my life
on Dec 22, 2010 at 9:30:13 pm

I have been supplied with a bunch of Standard Def 16:9 footage (1.2 aspect) and instructed that will be the output as well. I need to take much of it to AE for compositing and I'm just trying to do some simple apples-to-apples tests on exports/imports but I'm not coming up with apples. Here's what I'm doing and the results:

I'm exporting from Avid Media Composer as QT Reference files. So, there should be no issues there. AE interprets the footage correctly as DV Widescreen 720 x 480 1.21 aspect. To keep things simple, I'm just dropping the footage into a comp and rendering back out to the Avid so I can make sure things are, as I said, apples-to-apples. But, when I import, the file has taken on a slight bit of softness and has lost image detail.

On the After Effects side, I have tried just making a new comp from the footage (720 x 480 comp, 1.21) and rendering it, as well as placing the footage into a 720 x 486, 1.21 comp and rendering. I'm rendering a QT Movie using the Animation Codec and field rendering using lower field first (native to the footage).

On the Avid side, I'm importing the QT at 1:1, using 601 color levels and lower field first.

When I import the 720 x 486 rendered comp, I get the noticeable image degradation and softness. When I import the 720 x 480 rendered comp, I get better detail but also the typical slight jittery video you would expect from feeding the Avid anything that's not 720 x 486.

So, it's a very simple but very frustrating problem: What is the proper way to be handling this footage in AE so I get a correct import into Avid MC? I'm attaching 2 images, pre and post render to illustrate. Notice the detail in the vases in the top image. Thanks in advance for any help!





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Jason Brown
Re: the six pixels that changed my life
on Dec 23, 2010 at 1:09:22 am

What avid media composer codec are u using? Is it an older avid? U need to confirm that u r using DV and not D1.


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 1:35:36 pm

AE CS4, MC 3.01 Mojo.

I don't understand your DV/D1 comment. I've done renders both ways from AE (480H and 486H). It only imports into the Avid one way.


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Jason Brown
Re: the six pixels that changed my life
on Dec 23, 2010 at 2:10:18 pm

Well Dave,

I'm not understanding...my AVID experience was on Media Composer using Meridien hardware which is D1 - 720x486.

You say --

[Dave Fleming] "I'm exporting from Avid Media Composer as QT Reference files. So, there should be no issues there. AE interprets the footage correctly as DV Widescreen 720 x 480"

But then you also say -

[Dave Fleming] "but also the typical slight jittery video you would expect from feeding the Avid anything that's not 720 x 486"

Which, as I read it, sounds contradictory...does your AVID work natively at 480 or 486? I've never dealt with MOJO, but I think that is a DV system which would be 480.

-Jason


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 2:27:33 pm

Ah yes--there is a contradiction, you're right. But to explain it, now that's another story.

Here's the deal: The native files were captured on a Sony XDCam at SD Widescreen, which is 720 x 480 at 1.2 aspect. The Avid has no problem playing these files natively (that was the top image in my original post). But, whenever I feed the Avid anything coming from After Effects, it needs to be 720 x 486 or else I will get a slight jitter in the motion of the video. However, the 720 x 486 rendered file produced the bottom softer image.

I'm not sure why that is...I'm just trying to do the most basic of tests to see if I can get the same result out of AE as I have in the Avid. Thanks!


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 2:32:17 pm

Also, the Mojo is only a transcoder for material headed to or from videotape, which I rarely use anymore. The system definitely handles SD files at 720 x 486. Now, is it playing the DV files at 480 or tanscoding to 486? I have no idea what's happening under the hood.


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John Cuevas
Re: the six pixels that changed my life
on Dec 23, 2010 at 2:51:18 pm

Work with Avid and AE a lot...if you are creating QT Refernces you need to be exporting at 720 x 486, not 480. When Avid exports to 480, it doesn't crop it scales down and that will completely mess up the fields. Even if AE interprets it correctly, it's not going to come back to the AVID correctly. If you scale it up to 486 in AE, it's missing data and gives you that "soft look" you mentioned.


So export a QT Refernce with native dimensions. I've never had AE interpret a 1.21 Avid QT export correctly, so you will mostly likely need to use interpret footage to get to be 1.21.

Johnny Cuevas, Editor


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 3:14:51 pm

Thanks Johnny, you may have helped me hit on something...Initially, I thought your reply was wrong, because a native file is a native file when you're exporting QT Reference...i.e. you can't (or shouldn't) change the resolution.

But, then I re-examined my export workflow and discovered that I didn't have the "Use Avid DV Codec" option checked on the reference file. When it was unchecked, AE was interpreting the file as 720 x 480, 1.2 aspect. When it is checked, the file is interpreted as 720 x 486, .9 aspect.

Could that have made all the difference?


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 3:45:41 pm

OK, onto the next question: Assuming my video is now apples-to-apples, how in the world do I create graphics both inside AE and/or prepare them in Photoshop? When I was working in a widescreen 1.2 comp, the compensation was done for me, but now that I'm in a stretched .9 comp, graphics will distort on import.


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John Cuevas
Re: the six pixels that changed my life
on Dec 23, 2010 at 5:55:06 pm

You should still be working in a WS composition. I don't know why AE interpets QT's that come from avid as .91, but right click on the footage, choose "interpret footage" and make it 1.21. Either drag it to the create new comp button, or when creating a new composition choose NTSC D1 Widescreen.

Johnny Cuevas, Editor


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Dave Fleming
Re: the six pixels that changed my life
on Dec 23, 2010 at 6:05:17 pm

Thanks again Johnny--I had done this already but forgot to post a response. You're absolutely right. 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...oh well...at least I'm off and running on this project. Thanks for your help!


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Walter Soyka
Re: the six pixels that changed my life
on Dec 23, 2010 at 6:27:08 pm

[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


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Dave Fleming
Re: the six pixels that changed my life
on Dec 24, 2010 at 1:50:56 am

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


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Jason Brown
Re: the six pixels that changed my life
on Dec 23, 2010 at 6:30:04 pm

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.


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Gary Hazen
Re: the six pixels that changed my life
on Dec 24, 2010 at 12:51:36 am

[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.


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Jason Brown
Re: the six pixels that changed my life
on Dec 24, 2010 at 1:30:54 am

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


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Walter Soyka
Re: the six pixels that changed my life
on Dec 24, 2010 at 1:53:24 am

[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


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Jason Brown
Re: the six pixels that changed my life
on Dec 24, 2010 at 5:41:49 am

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


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