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brightness levels

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Yidhartha
brightness levels
on Sep 2, 2007 at 8:05:07 pm

Hey there,

I am a film editor that does basic DVD authoring for clients (not distribution) using DVD Studio Pro. On a recent project my DVDs are substantially brighter than the master file I am using to encode. Does DVD Pro do some sort of IRE shift up in its encoding? If so, what are my options for creating a DVD that accurately reflects the image values of the original.

Thanks

Eric GRush



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Noah Kadner
Re: brightness levels
on Sep 4, 2007 at 4:29:26 am

Depends on the source and on how it was compressed. The possibility for a gamma shift is definitely there with so many variables from source view to DVD.

Noah

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cowcowcowcow
Kieran Matthew
Re: brightness levels
on Sep 4, 2007 at 5:54:38 pm

Hi Eric,

DVDSP doesn't do anything to the IRE level, but its internal encoder is expecting the media to be in a certain form.

What you are probably seeing is a levels/gamma shift resulting from media with a different colourspace than Apple's codecs.

DVDSP is expecting media to be 1.8 gamma with levels in the 0-255 range (critically with black at 0). Some NLE's work with Media at 2.2 in the 16-235 range. Encoding this through DVDSP leaves you with overbright low contrast video with blacks distinctly grey.

The options are to encode separately in Compressor with setting adjusted to add contrast and gamma shift, or to use another encoder like Bitvice, which has a "studio RGB" button for this.

Hope that helps,

K


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Antonio Atzei
Re: brightness levels
on Sep 10, 2007 at 9:15:20 pm

Hi Kieran

[Kieran Matthew] "The options are to encode separately in Compressor with setting adjusted to add contrast and gamma shift, or to use another encoder like Bitvice, which has a "studio RGB" button for this."

Can you suggest how to compensate the offset in compressor. I tried various settings but without luck.
Should I just give it up and purchase bitvice?
I have Power Mac G5 QUAD with FCS 2 , oh yes i`m in Sydney so i`m a PAL kind og guy
Thanking you in advance



BABALOTTI PRODUCTIONS
SYDNEY
POWER MAC G5 QUAD SYSTEM
5.5GB RAM
1 TB OF MEMORY.
Blackmagic Decklink Intensity Pro
Dell 24" 2407 WFP
FCS 2




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Kieran Matthew
Re: brightness levels
on Sep 10, 2007 at 10:13:58 pm

Hi Antonio,

I'm in the UK, so I'm a PAL kind of guy too :-)

Off the top of my head, the most critical thing is to apply a gamma filter set to around 1.2 (There's a mathematical reason for this figure, but I've heard of people going as high as 1.4 and above).

Other than that, adding contrast and lowering the brightness does the rest, but I don't have exact figures (I've seen -5.6 brightness and +3.3 contrast posted by one cow-er, +16 contrast by another).

There's a demo version of bitvice you can try to see if it cures your problems and works well for you if you don't want to take the plunge straight away.

Hope that helps.

K


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