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DNX playback on FCP7 turns brighter?

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Francisco Belda
DNX playback on FCP7 turns brighter?
on Jan 16, 2013 at 6:10:48 am

Hello Guys!
(I apologize if this topic is discussed elsewhere, I searched on these forums, and abroad on google and haven't come up with anything)

I am having some trouble with a DNxHD quicktime on FCP.

First a little backstory: In our facility we have always worked with Apple boxes and FCP 7, we have begun to switch to PC boxes in the last months and have been trying to figure out a nice workflow to share media between stations. The Avid DNX codec seemed ideal: free, many compression options, lightweight, goodlooking. Very akin to the tried-and-true ProRes with the advantage that we can compress and decompress from both our PC's and Mac's. It seemed ideal but... When playback is stopped on our FCP with a DNX sequence the image turns brighter! A lot brighter, think at least a whole f-stop. We tried the same media, on the same Mac but in our Smoke and everything was perfect!

Any ideas?

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Shane Ross
Re: DNX playback on FCP7 turns brighter?
on Jan 16, 2013 at 5:35:39 pm

DNxHD isn't a realtime codec in FCP. It isn't one it is designed to work with. Smoke was designed with using it in mind.

Yes, it will work in FCP, but you won't get any RT effects (you'll have to render every dissolve and any time you add a filter or text), and it won't act as well as a native FCP codec like ProRes will.

If you want smooth workflow between PC boxes and Apple boxes...use one NLE that works on both. Avid MC 6.5 and Adobe Premiere Pro CS6 works on both.

Little Frog Post
Read my blog, Little Frog in High Def

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Chad Brewer
Re: DNX playback on FCP7 turns brighter?
on Jan 16, 2013 at 8:57:31 pm

Shane's correct that DNxHD is not a real-time codec in FCP as far as adding any transitions, filters, etc., but it "SHOULD" be a real-time codec for playback of a self-contained Quicktime. And it is, but as you've seen the black levels get improperly raised and it's most easily noticed when the playhead is stopped. I've been over this issue for years as the facility I work at is all FCP based, but we of course have to do mastering and other post work on DNxHD files from clients who are Avid based.

You can see the improper black levels in FCP of DNxHD files on the waveform scopes. Just try a DNxHD file of color bars only or watch the scopes when you pause the playhead. You'll also notice because of not being a real-time codec in FCP, that you'll see weird behavior of the FCP scopes when looking at the file.

And years ago, I finally figured out what's going on here. It's as simple as this: FCP misinterprets Rec.709 color space from these files. It's as if FCP thinks they are RGB, when they are actually Rec.709. So, you have FCP treating a Rec.709 file like it's RGB and the levels get whacked out of sorts. Primarily the black level.

The fix for this is to transcode the DNxHD files to Pro Res in Compressor. Compressor translates the color space correctly to the Pro Res file that will then be properly translated in FCP.

It's kind of an Avid on the PC and FCP don't play nice together thing.
So you could do what Shane suggested - use an NLE that works on Mac and PC.

Chad Brewer
Senior Videotape Operator
TeleVersions, LLC - Chicago

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Francisco Belda
Re: DNX playback on FCP7 turns brighter?
on Jan 17, 2013 at 5:53:27 am

Thanks for the response, guys!

To sum up: DNxHD is NOT the way to go to share assets between boxes and softwares. This is a bummer, I thought we had hit the answer to our woes. Transcoding it is, then.
Avid, FCP, Premiere, geez: to paraphrase Rodney King "Why can't they all just get along?"

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Rafael Amador
Re: DNX playback on FCP7 turns brighter?
on Jan 17, 2013 at 10:33:38 am

As has been said by Shane and Chad, is a problem with the poor capability of FC for color managing and QT for color space flagging, but in fact is one of the few quality cross-platform options.
Applications like AE or FCPX should manage it without problems.

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Dennis Radeke
Re: DNX playback on FCP7 turns brighter?
on Jan 17, 2013 at 12:56:21 pm

to answer the question: because a lot of companies (Apple, Avid, GV, etc). create propietary codecs or wrappers that you have to license - i.e pay money for in order to use.

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