Convert to Prores first or color correct first?

Abaddon

Abaddon

Well-known member
I'm getting ready to do the post work on my project shot on a Canon 5D Mark III. I'm cutting on Premiere and will be doing color grading either with After Effects of Speedgrade. Just wondering if I should convert to Prores before doing anything or color correct and noise reduce first, then export 10 bit Prores files. I do notice the video noise increasing when I convert to Prores first, so I'm not sure.

Any thoughts on the best proven workflow?
 
Are you using Magic Lantern, or are these the native canon files. If native, those are essentially 8bit h264 files. Converting them to 10bit ProRes would be unnecessary. But either way, color then convert. Conversions can add artifacts which will be amplified in the coloring process.

If if shooting raw with magic lantern, I'd say color first and then convert. The raw files will give you the latitude to push your image significantly, then when you convert to 10bit ProRes, you can still push the image a bit, but you won't need to as much because you've ready done most of the pushing in raw.

Of course there are many situations that could render this advice less than ideal, but this is a generic start/approach.

Main any case, best of luck with your project!
 
Thanks for the info. I didn't use Magic Lantern, just the standard settings. I'll work on grading first, then converting. The project will mostly be for DVD but some large screen showings may be possible.

Would you say that I should keep everything from start to finish in 8bit h264 and not convert at all?
 
My knowledge is strictly from experience so others may have more technical information on these processes. That said, you don't gain anything by up converting to 10bit. If anything, you run the risk of adding unwanted artifacts to the image. In your case I'd say stick to 8bit all the way through. Then, if you have time, try exporting your final finished edit to 10bit and 8bit, and try to see for yourself on your TV if you notice anything.
 
I'm not so sure that's the right way to do this. H264 is a compressed codec. If you stick with it in grading, you won't be able to introduce the subtle colors that fall in the 10 bit space that you'd have with ProRes. Converting to ProRes422HQ or ProRes4444 should not lose any quality, while staying in H264 will limit your options. The ProRes files will of course be a lot bigger, but they are far easier for all the programs to work with assuming you're on a Mac.
 
The one thing I did notice in converting h264 to Prores 422HQ is that the noise increased a fair amount. It seems like more noise reduction would then be needed, which is not ideal.
 
Andrius might be right. I wasn't aware that by upconverting and working with 8bit h264 files as ProRes would give you any advantage. But I suppose it could be that working in a 10bit 422 color space might allow you to, as Andrius said, introduce color tones that wouldn't be available in an 8bit color space. Now I'm gonna go give that a try! :)

My understanding was always that if you had 255 of each RGB, that you would not gain any more color by upconverting.

it sounds a bit counter intuitive but I think Insee your logic. And after all, I'm still learning things every day!
 
Abaddon said:
The one thing I did notice in converting h264 to Prores 422HQ is that the noise increased a fair amount. It seems like more noise reduction would then be needed, which is not ideal.
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I wonder if what you're seeing isn't so much an increase in noise in ProRes, but that when the H264 is played back the decode is hiding noise that's already present. Just a theory really as I haven't seen it myself. I do recall hearing from people who were using external recorders to get ProRes files that they were seeing more noise as some cameras HDMI outputs bypassed some of the noise reduction that happened at the internal recording stage. Is this what you're talking about, recording ProRes on an external recorder or are you seeing noise from taking your h264 file and running it through a conversion to ProRes?
 
Andrius Simutis said:
I wonder if what you're seeing isn't so much an increase in noise in ProRes, but that when the H264 is played back the decode is hiding noise that's already present. Just a theory really as I haven't seen it myself. I do recall hearing from people who were using external recorders to get ProRes files that they were seeing more noise as some cameras HDMI outputs bypassed some of the noise reduction that happened at the internal recording stage. Is this what you're talking about, recording ProRes on an external recorder or are you seeing noise from taking your h264 file and running it through a conversion to ProRes?
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I shot in H264 and then converted one of the files into Prores 422HQ. I did a side by side comparison and noticed that the new Prores version was noticeably noisier in certain darker areas. I did read somewhere that it is recommended to bring the original H264 into After Effects, take care of noise reduction, and then export as a Prores 422HQ file which can then be edited and graded later.
 
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