[Avid-L2] Re: DNxHD QuckTime FCP Import Question

Here's the article below. I don't get why the RGBsource_709 options imports properly when both RGB and 709 are selected. RGB will not be a fast import but according to the article both will come in at the right level. That part seems wierd because in my experience the RGB 709 setting on import has no effect with Avid codecs. Hence from the article I gleemed that the assumption with Avid codec QTs is the video level should be 709. Here's part of the article:

If you start with source material with RGB levels (0-255), such as the image above, you should select the RGB button in the QuickTime export options shown below. This is because the option in the QuickTime dialog specifies the levels of the source material. However, it isn't a disaster if you don't select the RGB button.

Assume you export two movies. The first has RGB level source material and is exported with the RGB option selected. This is called RGBsource_RGBOption.mov. The second movie has RGB level source material and is exported using the 709 option. This movie is called RGBsource_709Option.mov.

Select the RGB brightness option with RGB source material.

Importing Source Material With RGB Levels

When you import RGBsource_RGBOption.mov into the editor, select the 601/709 option to perform a quick import. Selecting the RGB button will bring the video in at the correct levels, but it will be a slow import. It is OK to select the 601/709 button as the levels within the QuickTime movie were converted to 709 compliant levels when the RGB button was selected on export. Quick import copies the 709 compliant video data from the QuickTime movie to the editor. See the image below for the optimal setting when bringing this movie into the editor.

Select the 601/709 option for import of RGB source material.

If you look at the levels while in color correction mode, you can see that the darkest black is 16 and the brightest white is 235 as shown in the image below. The left side of the color picker represents the darkest black value and the right side of the color picker represents the brightest white value. The levels of the imported media are correct.

When you export source material that is already 709 level compliant, as shown above, the 709 button should be selected in the QuickTime dialog options as shown below. The RGB button should never be selected in this scenario, as this will not import into the editor with 709 compliant levels. Assume you export two movies. The first contains 709 level compliant source material and is exported using the 709 option. This movie is called 709Source_709Option.mov. The second movie contains 709 compliant source levels and is exported improperly using the RGB option. This movie is called 709Source_RGBOption.mov.

--- In Avid-L2@yahoogroups.com, Dennis Degan <DennyD1@...> wrote:
>
>
> On Feb 5, 2010, at 1:41 AM, johnrobmoore wrote:
>
> > It is my understanding that the Avid DNX codec is alway considered to
> be 601 not RGB. When you check the RGB for export you are telling QT
> to adjust the video levels from RGB to 601 level when making the QT so
> that when the Avid imports it the levels will always be interpreted as
> 601 and come out right. By definition the DNX codec is 601. You can
> get fouled up if your source is RGB but you check 601 option then it
> will not lower the RGB levels to 601. If you are exporting from an
> Avid timeline that would be 601 space so I don't think it would be
> correct to check RGB on export. If you are exporting captured material
> that too would be 601 level. Am I missing something here. It was just
> last week I read about this and I thought the light had finally turned
> on for me regarding why some imports in Avid codecs don't change no
> matter RGB or 601 on import. Is my light fading, please say it ain't
> so.
>
> John:
>
> I can only tell you that if you export as anything other than RGB from
> Avid, the export will contain elevated black levels. That is my own
> personal experience when doing DNxHD145 1920x1080 Avid exports. If you
> export using 709 (for HD), the QT imported into FCP will have elevated
> blacks. By setting the Avid export's color space to RGB, the video
> levels are correct in FCP. I don't know if this is different from
> doing SD exports using 601; I'm talking about Avid HD exports which
> give you the choice to use 709 or RGB. In this case, RGB works
> correctly.
>
> Dennis Degan, Editor-Consultant-Knowledge Bank
> NBC Today Show, New York
>

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