Any solution to the h.264 gamma bug?

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Level 2

251 points

Any solution to the h.264 gamma bug?

I am one of those victims of the h.264 gamma bug. When I compress a movie out of Final Cut Pro using h.264, the gamma in the resulting video is too bright, making the movie look washed out. This happens regardless of whether I use Compressor or Quicktime compression, or even save a full quality and compress it later.

I'm using Final Cut 6.0.6, OS X 10.6.2, a MacBook Pro with an external HP monitor. Both the external (main) monitor and the built-in monitor use custom calibrations. I have also tried disconnecting the external monitor and compressing when the built-in monitor is the only one, but that makes no difference. I've also tried x264 but that did not improve anything either.

Thanks for any thoughts...

Mac OS X (10.6.2)

Posted on Jan 8, 2010 11:35 AM

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Answer 1

reicko

Level 1

0 points

Jan 8, 2010 8:25 PM in response to Brian Dunning

Yes, I've experienced this phenomenon as well. The H.264 codec squeezes down, compresses, all your beautiful color information into a tighter package but loses some of the color and luminance factors. I'm sure there's a more scientific description of what happens but anyway...

To my knowledge there is no filter for Quicktime that fixes this issue, that's just the way it will come out looking. But you can handicap your image, darken or otherwise adjust the gamma levels or color settings, so that when the "gamma bug" hits your video, you've already compensated for the change in brightness & color. You can use the Color Correct 3-way tool in FCP to darken the darks, mids and whites so that when the gamma shift takes place in creating the H.264, the output will look closer to the original image.

Now, this will take some playing around with. And it will probably vary some depending on the make-up of your source footage. But it's worth a shot if you want better looking H.264's.

Hope this helps.

~reicko

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Answer 2

Brian Dunning Author

Level 2

251 points

Jan 15, 2010 11:55 AM in response to reicko

No, you don't want to try and fix it by compensating. If/when the bug is fixed, your videos will suddenly all be too dark.

Common wisdom says you need the latest version of Perian installed (1.2 as of today) and the latest version of x264 (1.1.10 as of today). This seems to fix it for most people. It did not improve anything for me.

I have found that if I export x264 in a QT container (.mov) that I do not have the problem - colors and gamma look great. But if I use the exact same settings in Compressor to an .m4v, I do have the problem - all washed out. I notice that all the top video podcasts are in .m4v now, and many of the video sharing sites recommend against the .mov container for maximum compatibility. So I'm still stuck without a solution. (Saving the .mov then editing the filetype to .m4v does not work, by the way, though it would have been nice to have such a simple solution.)

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