Why is the image brighter after converting H264 to Apple Prores 422 in Compressor ?

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Jacobinetto Author

Level 1

10 points

Why is the image brighter after converting H264 to Apple Prores 422 in Compressor ?

Hello -

Very strange situation, keep reading please!

I am using Compressor to convert H264 1080p footage from a D600, to Apple Prores 422HQ for editing. Normal.

I am using the default Quicktime Settings named "Apple Prores 422 (HQ)".

The converted file is a bit brighter than the original... Why is this even possible! 😁 I find this a bit problematic because I'm loosing some details in the whites, at a way too early stage for signal alterationt!

So I tried different other stuff that you will find interesting:

• changing gamma correction in the codec settings had no effect

• I can see the change happening already in the Preview window

• and this is the best one : if I apply a resize, to anything, like 1919 X 1079, or 1280 X 720... then the color change does not occur, even when exported! If I apply a resize to the same size, then the output is brighter again.

I am proof checking in Quicktime 7 of course, with "FCP compatibility" enabled and disabled.

I know this is a hot topic and there are many unsolved aberrations like this around this topic, but maybe there is something I don't get ?

Thanks 🙂

Compressor, Mac OS X (10.6.8)

Posted on Jul 25, 2013 6:19 AM

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Answer 1

Best reply

Russ H

Level 7

22,432 points

Jul 25, 2013 10:46 AM in response to Jacobinetto

Hiey Jacob.

I'm not getting that.

Here are two screenshots of the waveform for an h.264 and Pro Res HQ clip.

Russ

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Answer 2

Jacobinetto Author

Level 1

10 points

Jul 25, 2013 11:35 AM in response to Russ H

Hey Russ,

Thanks for taking the time to help out,

Indeed on your screencap the converted file looks exactly the same. Nice house!

Here is a video of the process, where you can clearly see the difference, even on this compressed MPEG-4 video!

What is this ? 😐

LINK: http://wvorg.online.fr/posts/h264toprores-problem.mov

(let it load a few seconds, it's a quicktime movie)

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Answer 3

Russ H

Level 7

22,432 points

Jul 25, 2013 4:36 PM in response to Jacobinetto

Jacob,

Thanks for the link. I would say it's a lot more than a bit brighter and I'm at a loss why that would happen.

The only difference between what I showed you and your outcome is my source files were from a Canon 60D; like you I encoded using the Pro Res HQ stock settings. When I previewed them, there was no visual difference. After encoding I brought them into FCPX to see what showed on the scopes.

I'll think about this some more, but perhaps someone else will chime in with an idea.

Russ

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Answer 4

Jacobinetto Author

Level 1

10 points

Jul 26, 2013 5:17 AM in response to Russ H

Thanks Russ for the info; I would normally do exactly like you did too.

For now well... I converted them all in 1919 X 1079 lol, I never thought I would have to do this in my life! But at least it worked and the brightness seems the same...

Still very curious if someone has an explanation!

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Answer 5

Jul 26, 2013 5:59 AM in response to Jacobinetto

I'm having this exact issue as well. It seems that any codec in Compressor 4 results in a brighter preview.

Even just selcting any codec in the settings browser (not applying it to the source) gives a brighter preview.

Can anyone check if they too have this behaviour?

I get this with Sony nex 5n video, a h.264 file exported from fcpx, but with another h.264 exported from fcpx it does not happen. All 1080p. I can't see a pattern.

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Answer 6

Jacobinetto Author

Level 1

10 points

Jul 26, 2013 6:08 AM in response to gudbandsdalsost

I was using Compressor 3, so it's not Compressor 4 specific

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Answer 7

Russ H

Level 7

22,432 points

Jul 26, 2013 7:07 AM in response to gudbandsdalsost

Is the preview window accurate? In other words, after you output the file from Compressor 4 is it also brighter when opened in a player like QT or VLC?

Russ

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Answer 8

Jacobinetto Author

Level 1

10 points

Jul 26, 2013 7:12 AM in response to Russ H

Yes unfortunately it's exactly the same on the output file!

Maybe it's a programmer bug that occured on my install... 😐

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Answer 9

Russ H

Level 7

22,432 points

Jul 26, 2013 7:21 AM in response to Jacobinetto

Unfortunately it's not practical for me to test this on C 3.0.

If you are near an Apple Store, sometime take a sample clip and see whether this happens on another machine running C 4.0.

Russ

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Answer 10

Jacobinetto Author

Level 1

10 points

Jul 26, 2013 7:48 AM in response to Russ H

Good idea, will try on another computer. Thanks!

Will let you know 😎

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Answer 11

Aug 3, 2013 11:10 AM in response to Jacobinetto

I was just converting 1080p30 footage from my Nikon D800 and I encountered this same issue. Our subject is wearing a white shirt and the Apple ProRes 422 version is significantly overexposed such that we lost detail in the shirt pattern. I converted using Compressor 4. I even previewed using ProRes 4444 and it is overexposed the same way.