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Coloured Squares around High-Contrast areas after export ???

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Charlie Reader
Coloured Squares around High-Contrast areas after export ???
on Mar 24, 2013 at 10:10:52 pm

Hi guys,

I have rendered out a master of a music video I've made. The mater format is ProRes 4444. I have tried to encode the video to x.264 using Handbrake, but the exported file shows coloured squares around the edge of certain areas.

You can see what I mean in the photos:

Master Video Example Frame: http://www.flickr.com/photos/93980205@N02/8587683794/in/photostream

X264 Video Example Frame:
http://www.flickr.com/photos/93980205@N02/8587683918/in/photostream


Does anyone know what might be causing this/how I can get rid of them?

Thanks in advance!


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Brad Elliott
Re: Coloured Squares around High-Contrast areas after export ???
on Mar 25, 2013 at 2:54:46 pm

The artifacting that you are seeing is usually caused by the following:
1) The data rate
2) Colors/whites are too hot

No matter what the pixel dimensions of your file the data rate generally has the largest control over quality/size of your finished file.

I have had problems with compression that couldn't be easy explained and thought it was the codec that I was being asked to use. After checking my sequence in a waveform and vectorscope it was determined the whites and reds were too hot. Adding a broadcast safe filter and making some color adjustments solved the problem.

Where will your final deliverable be used?



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Charlie Reader
Re: Coloured Squares around High-Contrast areas after export ???
on Mar 26, 2013 at 5:54:40 pm

Hi Brad,

Sorry for getting back to me and apologies for my late response.

I used Handbrake to encode the master, using constant quality rather than setting a bitrate target. I also used scopes when grading the video so am fairly sure that it's all broadcast legal, although saying that I set black to 0/0.3 as it isn't going on television (only internet release), but this hasn't been a problem for any of my videos before using the same compression settings.

I will try what you said anyway though!

Thank you


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Jeff Greenberg
Re: Coloured Squares around High-Contrast areas after export ???
on Mar 27, 2013 at 11:08:54 am

Handbrake is a great automated tool for ripping DVDs. And while it 'works', it's not the tool I'd ever pick of choice. The Constant quality settings aren't always what you'd really like.

What it looks like happened is that you exceeded the data rate needs (handbrake guessed them wrong.) Do you have other tools? I'm assuming you have compressor, because you're handling a ProRes 4444 file. How about giving it to compressor and using the Youtube setting? Just compress that one scene (did you know you can set an in/out in compressor? It's great to test a difficult section of your video.) to test.

Last, I have seen problems like this with a corrupted QuickTime file or corrupted render, but that's not terribly likely.

Best,

Jeff I. Greenberg
Author/Master Instructor/Speaker/Consulting
My contact info and more
New! Come see me speak @ NAB/Post Production World!


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