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Using ProRes4444 when I don't need an alpha channel

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Seth Marshall
Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 1:51:35 pm

I would like to keep high fidelity in my image sequences from Canon 5DmkII raw files. ProRes4444 with 4:4:4 would retain the most color data but I never use transparency and wouldn't need an alpha channel.

I do not know how ProRes compresses, but if my alpha channel doesn't change would the file size be as if it was only saving RGB data and not alpha channel? Or would my files be bloated with data from an unchanging alpha channel?

I am needing a codec for archival. Otherwise I could use ProResHQ but its only 4:2:2.


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Walter Soyka
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 3:20:21 pm

[Seth Marshall] "I do not know how ProRes compresses, but if my alpha channel doesn't change would the file size be as if it was only saving RGB data and not alpha channel? Or would my files be bloated with data from an unchanging alpha channel?"

I have read elsewhere that the ProRes 4444 alpha channel uses lossless compression. A movie with full alpha shouldn't be wasting much space on the fourth channel.

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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Seth Marshall
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 4:32:00 pm

Thanks Walter! I guess if there's any compression, even if lossless, hopefully the algorithm would take into account situations where the alpha isn't needed and compress that channel entirely (like a losslessly compressed audio file for an empty sound track).

Otherwise if it's tied into the RGB channels it may eat up bandwidth. But I'm not an engineer, just overly concerned about file size.


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Dave LaRonde
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 4:05:26 pm

Then bear this in mind: even humble ProRes 422 can withstand 6 generations of re-rendering before even the most miniscule problems appear to the eye.

It seems that ProRes HQ might be a viable alternative for you. And if you're cutting in ProRes 422, even HQ would be unnecessary.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Seth Marshall
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 4:35:39 pm

Thanks Dave. I do like the 4:4:4 option but don't need an alpha. As long as the compression does the alpha independently then using 4444 won't be so bad.


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Dave LaRonde
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 5:41:10 pm

Well, there are few reasons to use ProRes other than in Final Cut Pro. If you match the codec of your FCP edit when rendering in AE, you're good.

Since anything more than ProRes 422 is overkill for your original DSLR video, you gain nothing by going to a higher-quality codec.

No, wait, that's not entirely correct. You DO gain something: unnecessarily large file sizes.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Seth Marshall
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 6:31:43 pm

Hi Dave, copy that for video from DSLR. But actually my files are raw stills (time lapse image sequences). I was the guy you helped yesterday with my mask issue. Thanks though :)

I just wanted to know the best codec for archiving the raw file image sequence before processing and after (so I can have an original and delivery both at highest fidelity).

I figure 4444 gains me 4:4:4 but depending on how the compression algorithm I'll either waste bandwidth on an unnecessary Alpha channel or ideally the Alpha channel will recognize there is no transparency information and dedicate bandwidth for RGB or give me a smaller file.


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Dave LaRonde
Re: Using ProRes4444 when I don't need an alpha channel
on Apr 11, 2013 at 6:43:23 pm

That's a tough question to answer without knowing your delivery specifications.

AE is all about delivering your work to the NEXT piece of software you will use. Only in the most rare of circumstances would one ever create work that would be immediately used from AE.

Without knowing what comes next, we're clueless.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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