Proxy Clarification

[Jeff Brown]

Chaps,

Been playing with 2k H proxies in FCP. I did a split screen comparison of the H proxy with a Redcined rendered 2k prores version of the same shot. Now I know the H proxy is supposed to be 1024 x 512. My rendered version is 2040 x 1024 and in my timeline the H proxy is scaled 200% to match. The thing is they appear to be of exactly equal quality when rendered to prores. No sign of aliasing/compression etc. (with the M and P proxies it's really noticeable)

So what is going on here? The H proxy references the 2k .r3d so is it scaling its decode to match? Ideally I'd like to finish from the proxies and avoid transcoding to get a 1080 finish - the final destination being web based. So if I scale up my 1024 x 512 how much quality am I really losing?

On another note if the proxies are 8 bit but I convert my sequence to 10 bit prores and render am I effectively then creating a 10 bit sequence from the .R3d reference or is the 8 bit baked to the proxy?

Thanks in advance for feedback on my ponderings.

Cheers

Jeff Brown
#708

[cjderosa]

What build are you on. In 15 the _h proxy is upped to 2048x1024 (i was on build 13 with _h equaling 1024x512) which would explain why the quality is equal to the prores'd 2048x1024. Check your proxy resolution.

My real question is - DO WE KNOW DEFINITIVELY THAT PROXIES ARE ONLY 8BIT??

In all the side by side testing i've done, between proxies and redalert outputs - i see no difference in quality.

[Deanan]

Proxies will be 32bit float when you set FCP to high precision yuv in settings->video processing.

[Uli Plank]

Be careful, though, to use only filters and transitions that run in 32 bit float or you'll loose that quality. Not even all of Apple's own filters are ready for it.

Have a look at these articles:

http://www.coremelt.com/support/workflow/red-camera-10-bit-color-online-workflow-with-fcp-6.0.2.html

http://www.coremelt.com/support/workflow/codec-and-effects-limitations-for-10-bit-online-workflow-with-final-cut-pro-6.0.2.html

http://www.noiseindustries.com/support/technotes/files/high-precision_rendering_in_rgb_and_yuv.html

Regards,

Uli

[Jeff Brown]

Thanks for confirmation of the 32bit float.

Regarding the proxy size - I'm on 15.2.1.7 and on my 2k my H proxies are still 1024 x 512. I know there's now an F proxy but that currently doesn't work with anything. Do we know when that will be enabled?

Also, Deanan any confirmation on wether the H proxy is scaling in my timeline (it looks as good as the 2048x1024 prores) or is it definitely locked to 1024x512 and I just can't tell the difference!?

Rgeards

Jeff

[Stuart English]

Thanks for confirmation of the 32bit float.

Regarding the proxy size - I'm on 15.2.1.7 and on my 2k my H proxies are still 1024 x 512. I know there's now an F proxy but that currently doesn't work with anything. Do we know when that will be enabled?

Also, Deanan any confirmation on wether the H proxy is scaling in my timeline (it looks as good as the 2048x1024 prores) or is it definitely locked to 1024x512 and I just can't tell the difference!?

Rgeards

Jeff

Did you shoot the original .r3d at 4K or 2K?. And are the proxies from the camera? The _H proxy should always be always half the original .r3d pixel H and V size.

[Stuart English]

Regarding the proxy size - I'm on 15.2.1.7 and on my 2k my H proxies are still 1024 x 512. I know there's now an F proxy but that currently doesn't work with anything. Do we know when that will be enabled?

Also, Deanan any confirmation on wether the H proxy is scaling in my timeline (it looks as good as the 2048x1024 prores) or is it definitely locked to 1024x512 and I just can't tell the difference!?

Did you shoot the original .r3d at 4K or 2K?. And are the proxies from the camera? The _H proxy should always be always half the original .r3d pixel H and V size.

[Jeff Brown]

Hi Stuart,

I shot 2k .r3ds and am using the H proxies (1024x512) in a timeline that is 2048x1024 - so scaled to 200%. FCP is set to high precision rendering YUV and rendering the sequence in proresHQ.

I'm doing this to compare the quality difference between rendering out a 2K prores from redcine and working from the h proxies.

To my eye there appears to be little difference in terms of resolution/aliasing although of course the proxy is a more contrasty image.

I was really just curious to know what the proxie is doing and weather it is fixed at 1024x512 or weather it scales on the fly

Cheers

Jeff
#708

[Kenn Michael]

Did you render your RedCine ProRes file at 'Full' or 'Standard'?

If Standard, then RedCine is effectively using half the 2K resolution (hence looking like a 1024x512 image scaled 200 percent).

If Full, then RedCine is using all the resolution - where it should look better than the 1024x512 upscaled.

When shooting in 2K, it's imperative that you render 'Full' out of RedCine to get the best looking images. When the '_F' proxies work, then at least you'll be getting all the pixels from your original footage.

[Jeff Brown]

Hi Kenn

Tried it with full demoisaic from Redcine. The difference is negligible I feel - I'm thinking for SD / Web destined projects it may be a quick and easy workflow that avoids the full trranscode times..

Full size proxies would be welcomed and of course if I can get Crimson working OK....

Cheers

Jeff

[Deanan]

_F, if it works on some systems (i believe leopard and the latest codec), is a scaling being done by QT. Proper _F support will likely appear in about 3-6 weeks if all goes well.

[Kenn Michael]

I believe I'm on the latest version of the codec as well as Leopard and the _F proxies don't work for me.

Bring on Build 16 and the new apps!!!!! :)

[Cüneyt Kaya]

difference between 2k proxies and 2k Pro Res out of redcine?
its not 8 bit vs. 10 bit, right?
its not the resolution you say?

So what is the difference?

-----more precise : how are the proxies defined?

[Jeff Brown]

Sorry Deanan - didn't quite get what you meant in that last post. Are you saying that my H proxies are scaling in QT in this instance? So although its 32 bit float I'll still have aliasing and so an inferior image to the prores I create in Redcine from a full debayer. Have I got that right?

I'm latest codec and Leopard with latest graphics update and I can't get F proxies working yet.

3-6 weeks is cool. Looking forward to it.

Cheers

Jeff

[Deanan]

Bottom line for _F: Don't use them right now. The fact that it works on some systems is just a coincidence and is totally unsupported.

Bit depth is separate from resolution so if you're using the proxies, they will be lower quality than doing a full debayer and scaling down. For some workflows, the proxies are completely usable as half res high quality. For other workflows, a full debayer is necessary. RedAlert also has a half res debayer right now which is a high quality debayer that's alot faster than the full res debayer but but very close in quality to full res debayer.

So in order of quality for a 4k source and 2k output:
1. Full res debayer w/ a down scale.
2. Half res debayer direct to 2k (redalert only at the moment)
3. _H proxies

[Jeff Brown]

Thanks Deanan

That clears up a lot.

Cheers

Jeff

[jimhare]

"F" works on my system! Just tried it. Pretty wild seeing it fill my 1920 monitor with 1/4 of the image! Plays at about 12FPS or so with audio.

Mac Pro 2 x 2.66 Leopard 10.5.2, 7GB RAM, QT 7.4.5.