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Topic: Best export format from ProRes 422 for E-Cinema?
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Jim Cassedy
Phenomenal Film Handler
Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 03-14-2017 02:43 PM
Ok- - I can't claim I'm an expert in this particular area, but I've had to deal with this kind of thing on a regular basis for the last 7 or 8 years. So when I first started doing that, I did a lot of "Google-ing" and it seems that ProRes 422 is fine 99% of the time
Generally speaking - - unless you're projecting onto a huge screen, or dealing with 4K, the extra huge file sizes of 422HQ aren't going to buy you that much more image quality.
Also, from notes I took when investigating this- - 422HQ which has a 10bit pixel depth, isn't going to make something mastered with an 8bit pixel depth (which many projects are) look any better. Also, 422HQ requires a much higher data transfer rate to play properly, which, depending on your combination of software or hardware, may be tricky to achieve. I was recently called in to troubleshoot playback problems for a local event which was using ProRes 422HQ & was experiencing playback problems. Their entire issue was that their hardware couldn't handle the extra data rate of 422HQ. (7200rpm drives are almost a must)
Long story short- - I've been using plain old Pro-Res 422 for several years at dozens of small & large film festivals and corporate events. - - and I've never had any complaints from either attendees or the film makers about image quality. IMO 422HQ is overkill. (Sure, you can buy a car that goes 200mph, but how often do you need to go 200mph?)
That's my .02cents worth, based on my personal experiences.
Here's some info I've had filed on my computer for some time explaining the difference in Pro-Res versions, mainly as they apply to editing, but I kept it because it explained the different pro-res formats in 'plain language':
ProRes 4444: virtually lossless, extremely high-fidelity codec, only to be used with high-end acquisition formats such as HDCAM SR, AVC-Intra and the likes, AND when doing high-end multiple generation compositing or keying OR when you need to export high-end video with alpha channel (roundtripping to third party applications).
ProRes 422(HQ): virtually lossless codec, only to be used with high-end acquisition formats such as HDCAM SR, AVC-Intra and the likes, AND when you need high-end compositing or keying.
ProRes 422(regular): virtually lossless codec to be used with most common acquisition formats (HDV, EX, AVCHD...) and when you need multiple generations in editing or compositing (multiple layers, renders or exports).
ProRes 422(LT): relatively lossless codec, to be used with most common acquisition formats and where no heavy editing or compositing is involved.
ProRes 422"Proxy": for first generation viewing and editing (cuts only).
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Antti Nayha
Master Film Handler
Posts: 268
From: Helsinki, Finland
Registered: Oct 2008
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posted 03-18-2017 05:06 AM
quote: Jim Cassedy 422HQ which has a 10bit pixel depth, isn't going to make something mastered with an 8bit pixel depth (which many projects are) look any better.
All ProRes 422 variants have a 10-bit sample depth, the only difference is the bitrate. The nominal/average bitrates for 1920x1080 24p content are:
ProRes 422 HQ: 176 Mbps ProRes 422: 118 Mbps ProRes 422 LT: 82 Mbps ProRes 422 Proxy: 36 Mbps
I've done a few tests with extremely grainy, difficult-to-compress material, and I could see absolutely no difference between 422 HQ and 422 even when zooming in on a still image. So yeah, HQ is definitely overkill for projection purposes, no matter how huge the screen. And like Jim, I've also experienced cases where the playback equipment couldn't handle HQ's extra bitrate – note that ProRes is not a constant bitrate codec, so the bitrate rises even higher when encoding very grainy/complex material.
I would go so far as to say that even ProRes 422 LT is perfectly fine for projection, too. I'll have to do some more close-up tests at some point, but even if they do show a difference when zooming in on a freeze frame, I doubt that it's actually visible on a moving image.
ProRes 422 Proxy, on the other hand, is definitely visually lossy and should be avoided for this purpose.
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