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Generation loss & after effects

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James MartinGeneration loss & after effects
by on Nov 25, 2011 at 12:00:08 pm

A question for you that reflects my ignorance of how AE's back-end works:

With FCP, as I understand it, if you drag a clip into a new sequence and set the sequence to the clip's specs, you can export that sequence ("current setting"), reimport that new file, export & re-import it, infinitely without any generation loss as FCP isn't re-encoding the clip each time. Correct me if I'm wrong.

With AE I'm less sure. Say you drag a ProRes422 clip into a new comp and set the comp to have the clip's dimensions and time-base, then render out the clip as ProRes422 (the codec it started as).... could you do the same as FCP, reimport and render out infinitely without generation loss, or is AE re-encoding it each time. If not is there a way you can bypass that generation loss (at least in theory as I'm not sure why you'd do that in the first place)?

Thanks,

James


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Chris WrightRe: Generation loss & after effects
by on Nov 25, 2011 at 12:33:11 pm

all your answers here. in a nutshell, 422 is not generational, you'd want prores444.
http://www.simvideo.com/resources/Post/ProRes_422_WhitePaper.pdf




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James MartinRe: Generation loss & after effects
by on Nov 25, 2011 at 1:08:52 pm

Thanks for your response, Chris. I'm not sure if I've misunderstood you or vice versa, but my query doesn't relate to ProRes per se, but any format and the way AE spits out a clip if you try to preserve that format. Substitute ProRes in my original post for DV or h264 or any codec - where FCP would refer back to the clip and export without re-encoding, I'm trying to find out what AE would do.

Thanks,

James


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Michael SzalapskiRe: Generation loss & after effects
by on Nov 25, 2011 at 6:14:42 pm

AE and other pixel-based compositors such as Flame, Shake, Fusion, etc. are not like an NLE. They creates new pixels for every frame.

So, if you give AE a compressed file, like h.264, it will create new pixels on every frame based on the incomplete pixel data in the file (incomplete because it's a long GOP codec). And, if you render to a compressed format like H.264, it will simply create a new h.264 based on the pixel data it has created with absolutely no relation to the original h.264.

You don't ever want to render an h.264 from AE anyway. From AE, you always want to render a lossless file and then use that in your NLE or compression software to make your final file. From Dave LaRonde:
Dave's Stock Answer #3:

Don't use AE to compress files for final delivery. The various compressors are there only to make quick 'n dirty files showing a project's progress to producers, clients, the kids, etc. AE is incapable of doing multipass encoding, a crucial feature that greatly improves the image quality of H.264 and MPEG-type files in particular.

Render a high-quality file from AE, and use a different application to do the compression. Popular ones are Adobe Media Encoder, Sorenson Squeeze and Apple's Compressor, which comes bundled with Final Cut Suite. Even compressing in Quicktime Pro is better than compressing in AE.


- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Todd KoprivaRe: Generation loss & after effects
by on Nov 25, 2011 at 8:23:10 pm

Michael is correct.

If you want to avoid generational quality loss with your intermediate files, you must use a lossless codec. Animation and PNG are the two lossless codecs that come with the standard QuickTime installation. I use the PNG codec in a QuickTime container for my intermediate files.

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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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Chris WrightRe: Generation loss & after effects
by on Nov 25, 2011 at 11:48:23 pm

don't forget, unlike prores' 444 10 bit (trillions of color); animation and png in the quicktime container only support 8 bit (millions) color so if you do any color manipulation, there's a small error pixel shift.


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Walter SoykaRe: Generation loss & after effects
by on Nov 26, 2011 at 2:03:57 am

[Chris Wright] "don't forget, unlike prores' 444 10 bit (trillions of color); animation and png in the quicktime container only support 8 bit (millions) color so if you do any color manipulation, there's a small error pixel shift."

You could also render to cross-platform OpenEXR sequences to keep the color depth without ProRes's lossy compression.

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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Roland R. KahlenbergRe: Generation loss & after effects
by on Nov 26, 2011 at 7:21:34 am

And if you're working with EXR files, then take a look at ProEXR - http://www.fnordware.com/ProEXR/

HTH
RoRK

Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer


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Todd KoprivaRe: Generation loss & after effects
by on Nov 26, 2011 at 7:46:00 am

Note that ProEXR is included with After Effects. See this page.

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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
---------------------------------------------------------------------------------------------------------


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James MartinRe: Generation loss & after effects
by on Nov 28, 2011 at 9:12:42 am

Wow, thanks - great answer.

I work A LOT with ProRes as Im usually dealing with SLR footage. I common step in my workflow is to take ProRes clips, or other video assets, that need dramatic color correction (beyond what I'm doing in FCP) or some simple compositing. To get them back into the edit, I'll render out in ProRes (so the clip sits natively in the sequence). Is that wrong? Should I be rendering out animation and compressing that with QT or compressor, then?


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Walter SoykaRe: Generation loss & after effects
by on Nov 28, 2011 at 11:42:15 am

[James Martin] "To get them back into the edit, I'll render out in ProRes (so the clip sits natively in the sequence). Is that wrong? Should I be rendering out animation and compressing that with QT or compressor, then?"

Rendering directly to ProRes from AE is a fine workflow (and an exception to Dave's Stock Answer #3).

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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