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Old February 22nd, 2009, 09:02 AM   #1
Inner Circle
 
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HD, IRE and Setup

Hello,

I have recently moved to HD production and wanted to run some things by the community to see if you are exeriencing this.

Back in the SD days, when I edited a project for television consumption if I decided to put a file on the web, I would make a Windows Media file, place it on my site and the levels looked very similar to the DVD.

In the HD world, what looks correct on my production monitor for DVD use, turns out to look under exposed when I make a web file and put it on the internet.

So I am finding that I have to "bump up" any footage for web use.

Anybody else noticing this?

Is it possible that the REC 709 color space differs from the color space of computer screens and the difference between 16-235 IRE and 0-255 IRE really shows more?

I thought the HD material would be closer to computer screens.

I am using Edius as my Editor.

BTW, my older SD material looks properly exposed on the monitor, so I don't think the monitor is out of calibration.

Thanks for your input.
Tim Polster is offline   Reply With Quote
Old February 22nd, 2009, 09:36 AM   #2
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Here is an article that you may have already seen.

Convert HDV for Superior DV
Reuben Miller is offline   Reply With Quote
Old February 22nd, 2009, 09:43 AM   #3
 
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Hi Tim....

You didn't mention what NLE you're using, and in my experience the luma problems you're seeing are really codec problems that extend across NLE's and apply to specific codecs and workflows. In the Avid realm, files can be imported as RGB (0-255)or Rec601/709(16-235). Likewise, files can be exported with the same choice. However, many codecs don't apply the differences and simply adjust the file according to hardwired approaches. The net result is that if you import as REC610/709 and you export to particular codecs, the codec will bump the output, automatically, to 32-241. One needs to be acutely aware of how the file is imported, how it is exported and all the intermediate and final codecs used. The best procedure I've found is to carry along a SMPTE colorbar pattern with a pluge to test the workflow, end to end.

I am looking at every step in my workflow with a waveform monitor and vectorscope, verifying which workflows are distorting luma values incorrectly. Some NLE's, like Vegas, will automatically import as REC601/709, giving you no choice for the extended range files typical of RGB. In the case of Vegas, an internal filter correction must be applied. The most frustrating part of this is that some codecs will ignore the luma remap and bump luma values without telling you. Frustrating indeed.

I really don't think this is a REC601/709 difference. While the color mapping is different for each spec, the differences are very, very small. Luma values are RGB16-235 for both specs, altho' in REC709 superwhites (ie whites above RGB235) are allowed. If the superwhites aren't handles properly in the NLE, they get clipped when exported.
Bill Ravens is offline   Reply With Quote
Old February 22nd, 2009, 10:08 AM   #4
Inner Circle
 
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Hi Bill.

I am using Edius 5.

I posted on the Edius forum as well. Maybe I am missing a setting which tells the output module to adjust for 0-255 viewing?

So many variables...

So what I am seeing should be handled by the export codec/software and probably is not a color space difference?

I notice that After Effects has two selections for REC 709 output/color space, 16-235 or 0-255.

I wonder if Edius has this kind of setting?

Thanks
Tim Polster is offline   Reply With Quote
Old February 22nd, 2009, 10:55 AM   #5
 
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Ahh..importing into AE has the problem I am referring to. You need to select the appropriate standard. Since I don't use AE, I can't help you with which one to use.

Edius has an export option, depending on which codec you're exporting to. You also need to set up the option to use "superwhite" or not. If you're source is DV, do not select this option. If your source is HDv, then DO select this option.
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