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DNxHD 185 vs "Same as Source"

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stig olsen
DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 5:47:36 pm

Hi,


When exporting the file as RGB "same as source" from my timeline for encoding in a third part app, it looks like the apps are confused if should mark the file with black as 0 or 16. When opening this file in lets say QT, it can look like the black is set to 16 and when opening the same file in WMP it can look like the black is set to 0. Or vice versa.

When exporting the same file as RGB "DNxHD" from my timeline for encoding in a third part app, it looks like the apps really understand that it actually is RGB and put the black at 0 no matter what player is used to see the final film.

All the material on my timeline is 709 and all the material is imported the old fashioned way. DNX.

Any insight?


Stig


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Michael Phillips
Re: DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 6:09:23 pm

An Avid RGB_709 project still has blacks as per SMPTE video at 16 and whites at 235 (using 8 bit terms). Same for 10 bit.

Michael


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stig olsen
Re: DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 6:14:36 pm

That is the reason I remap to RGB when exporting.


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stig olsen
Re: DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 6:38:24 pm

The thing here is that the two files follow the same route but one of them (same as source) is confusing the players (0-255 or/and 16-235) and the other one (dnXhd) keep the levels constant at 0-255.


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Job ter Burg
Re: DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 7:39:09 pm

One of them (Same As Source) is just a rewrap of your final sequence into a QT container. The other is a Quicktime re-encode using the DNxHD QT Codec.

Using the first, the 'RGB' setting merely adds a display tag that will make QT player remap when playing back. Not all apps may consider that tag.

Not sure what happens with that remap tag if you use the latter, but it is a very different way to create such a file and it does mean an extra generation of DNxHD.


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stig olsen
Re: DNxHD 185 vs "Same as Source"
on Jan 13, 2014 at 9:06:50 pm

Job ter Burg, you are a genious. I think QT sometimes doesnt understand the tag created in the "same as source" file. I will be using DNxHD from now on. I want control over the black level in all players.


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Bill Ravens
Re: DNxHD 185 vs "Same as Source"
on Jan 14, 2014 at 1:09:36 pm
Last Edited By Bill Ravens on Jan 14, 2014 at 1:14:03 pm

For a while I was using Hamlet's Videoscope to read and measure my final output file color and luminance values. I began to notice the curious phenomenon that ALL my Quicktime wrapped files were 16-235. At this point, I started using external WFM's to confirm what Videoscope was telling me. I discovered that Quicktime will consistently remap luma values during playback, even if the original footage is already 16-235. The net effect is that 16-235 native footage will display as something like 32-220, giving that chronic milky washed out look. And 0-255 native footage will display as proper (16-235) REC709, even if the footage is actually 0-255.

As far as I'm concerned, it would be a HUGE step forward if QT gave the user the ability to set the flag in the header. But, I know I'm just day-dreaming as Apple will never relinquish this control.



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stig olsen
Re: DNxHD 185 vs "Same as Source"
on Jan 14, 2014 at 2:49:36 pm

Hi Bill,

Did you notice this on QT wrapped files only (same as source)?

Stig


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Bill Ravens
Re: DNxHD 185 vs "Same as Source"
on Jan 14, 2014 at 3:48:06 pm

yes, only on QT wrapped files. If I played the same file on WMP, it would appear "correct".



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