Calibrated Software MXF Import v3 - Manual (Page 23)

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supply this Color Level setting to the Avid QuickTime Codecs so that they will know whether to use SMPTE RGB or Full
Range RGB.
Another interesting facet of the Avid QuickTime Codecs is the QuickTime Gamma that is reported when 8-bit YUV422 is
requested from the Avid QuickTime Codecs. QuickTime Gamma can be a very confusing and complex topic but to keep
things simple
– traditionally the QuickTime Gamma for YUV is reported as 2.22 for HD and 2.2 for SD, while traditionally
QuickTime Gamma for RGB is report as 1.8 on the Mac and 2.5 on Windows ( this is known as ‘QuickTime Platform
Gamma’ – for the gamma of the platform that you’re on). In more QuickTime-centric applications (such as Final Cut Pro
and FC Studio applications), Gamma correction is also applied when converting to and from YUV<->RGB. When
decoding DNxHD to YUV, the QuickTime Gamma that is reported by the Avid QuickTime Codecs
is the ‘Platform Gamma’
and not the traditional 2.22 for YUV HD in QuickTime. It is unknown at this time why this is done in the Avid QuickTime
Codecs but presumably this was done so that QuickTime would not possibly perform any Gamma Correction during
YUV<->RGB transformations
– while this can be beneficial in some workflows (and we’re not trying to second guess why
Avid designed their codecs the way they did) and many applications do ignore reported QuickTime YUV Gamma - by not
reporting the ‘expected’ QuickTime Gamma for YUV this can also cause color differences in more QuickTime-centric
applications like FCP and FC Studio applications where they are expecting to see the traditional QuickTime Gamma of
YUV being reported.
So with these considerations in mind:
(1) Color Level Setting to report to Avid QuickTIme Codecs for decoding DNxHD
(2) Avid QuickTime Codecs report a ‘Platform’ QuickTime Gamma when DNxHD is decompressed to YUV data
the following options in the next sub-section have been added to Calibrated{Q} MXF Import.
Possible Issue in 2.3.7 Avid QT Codecs for DNxHD444: For working with DNxHD444 (RGB- encoded DNxHD that’s new in Avid MC6) – you will need to
have the Avid 2.3.7 QuickTime codecs; however at this time there appears to be an error if 8-bit RGBA is requested from the Avid QT Codecs for
DNxHD444 data
– on Mac OSX the decoded 8-bit RGB video will look gray with a gray plaid overlay and on Windows 8-bit RGB will always be decoded
as SMPTE RGB regardless if Full Range RGB is selected. 16-bit RGBA and 8-bit YUV422 colorspaces appear to behave as expected.
Overview of the ‘dnxhd’ options in Calibrated{Q} MXF Import
IMPORTANT: These options are GLOBAL in nature – meaning the options will apply to all DNxHD MXF files, 1-1
10bit MXF files,and Meridien MXF files that Calibrated{Q} MXF Import is opening for any application on the
computer.
There three options that you can choose for each of the different video formats are:
(1) SMPTE RGB (16-235) (DEFAULT OPTION)
(2) Full RGB (0-255)
(3) Full RGB (0-255) & Gamma Ext. (BETA OPTION)
These three options can be independently set for DNxHD (YUV based), DNxHD444 (RGB based), 1-1 10bit YUV
(Uncompressed), 1-1 10b RGB (Uncompressed) and Meridien MXF Files as these are the video compression formats that
Calibrated{Q} MXF Import uses with the Avid QuickTime Codecs. Please note that for simplicity sake we will only refer to
‘DNxHD’ when describing how to use the options for all five of the Avid formats that use this option.
Please note that the number ranges used: 16-235 and 0-255 in the menu choices are used for simplicity sake as a point
of reference for YUV<->RGB color levels. 16-bit RGB conversions would obviously not be limited to values less than 255,
and would have much higher levels but in similar ranges.