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Andrew TurnerExport question
by on Jan 25, 2010 at 12:57:45 am

Hi All,

I'm currently exporting a uncompressed 4 min clip in AE to a .mov using the DVCPRO codec. I was wondering If pull the exported clip back into AE and for instance do a time warp on the clip and export it back out using the same codec settings, will the clip be re-compressed or should the quality be the same.?

Im thinking because compression has already been aplied to the video then it will be further compressed or will AE recognise that it's using the same codec as the source and destination and not recompress.?

Cheers
Andrew Turner


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Todd KoprivaRe: Export question
by on Jan 25, 2010 at 4:29:16 am

> will AE recognise that it's using the same codec as the source and destination and not recompress.?


No.

What you're asking for doesn't really make sense for a compositing and motion graphics application, like it would for an NLE. When frames come into and go out of an NLE, they're usually the same images---just different snippets of footage reordered. But, when you do just about anything in After Effects, you're changing the images; that's the whole point of using After Effects or any other compositing and motion graphics application. Even when you're just doing a time stretch, you're interpolating frames and creating a lot of new image data.

After Effects works with uncompressed frames internally. That's what you see in your Composition panel. When frames get rendered for output, the codec of the source footage isn't relevant.

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Andrew TurnerRe: Export question
by on Jan 25, 2010 at 6:15:33 am

Hi Todd,

I completley understand your point. I am using AE to do a frame rate conversion using the turorial at
http://library.creativecow.net/articles/kramer_andrew/fps.php

I have done a small test and the result was great. My project is a video clip shot on a Canon 5d MK2 at 1920x1080 30fps. One of the deliverables is SD 25fps PAL. The reason for asking the question was to reduce file sizes and time for rendering. At the moment my workflow is
Sony Vegas export, uncompressed quicktime 720x576 30fps. This file is around 10gig. I then import that into AE, apply the frame conversion and render out to an uncompressed quicktime 720x576 25fps. From this I can then make a DigiBeta master. This should take care of the PAL SD component but at the moment the render out of AE is showing around 20 hours for a 4 min clip.

My thought was that if I can use something like the Cineform Codec to export out of Sony Vegas and then keep the same codec in AE, would this reduce the render time.?

At the moment all I am trying to achieve is a HD Master clip and a SD PAL Master clip and from scouring the web the best software frame rate conversion seemed to be AE


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Walter SoykaRe: Export question
by on Jan 25, 2010 at 3:42:36 pm

[Andrew Turner] "My thought was that if I can use something like the Cineform Codec to export out of Sony Vegas and then keep the same codec in AE, would this reduce the render time.?"

I'd doubt it. As Todd mentioned, AE doesn't pay any attention to what codec you're using. It decodes the frame, works with it internally as uncompressed, and then encodes it again on render.

Unless your render is disk-bound (which is unlikely; standards conversion tends to be processor-bound), you won't see any time savings from using Cineform, and you may even see a slight performance and quality hit from the extra decode-encode cycles.

[Andrew Turner] "At the moment all I am trying to achieve is a HD Master clip and a SD PAL Master clip"

A big red flag here: if your HD material and your SD material are each running at different frame rates, you will not have consistent time code across your clips, so won't be able to easily conform one edit to another. In other words, if these are source clips for another project, you will have to edit two versions (HD and SD PAL) by hand.

Hopefully I've misunderstood, and you're doing standards conversion as the last step in your workflow on your edited output.

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
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Andrew TurnerRe: Export question
by on Jan 25, 2010 at 11:52:31 pm

Thanks Walter and Todd for clearing this up. Knowing AE decodes then re-encodes has cleared a lot of things up.

The Frame rate conversion is the last step in my workflow Walter.

Thanks again. This has cleared up my confusion.

Cheers
Andrew Turner


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