Calibrated Software MXF Import v3 - Manual (Page 22)

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Overview of YUV/RGB in Avid Media Composer
Avid Media Composer is aware of the color level differences of YUV and RGB data, and Avid MC allows workflows where
YUV can be converted to/from SMPTE Range RGB, thus preserving the Super White and Super Black values of YUV.
Basics of Importing Media into Avid MC
When importing files into Avid MC via the
‘Import…’ command from the Avid Media Composer application menu, Avid MC
will usually convert the incoming media to a flavor of DNxHD (usually the YUV-based DNxHD) and one of the import
options that Avid MC gives you is to identify the incoming media as you hav
ing either SMPTE RGB via the ‘601 SD or 709
HD (16-235) ’ option or ‘Computer RGB (0-255)’ and Avid MC will compress the incoming media to DNxHD based on the
When importing via AMA Linking, Avid Media Composer is able to decompress and read the compressed video data
natively
– thus Avid MC AMA Linking can avoid any unnecessary YUV<->RGB conversions.
Basics of Exporting QuickTime MOV files from Avid MC
When exporting from Avid MC, you can export into a wide range of formats
– but for the purposes of this User Guide we
will only go over exporting DNxHD MXF files as DNxHD MOV files in Avid MC.
In Avid MC, you can right-click on a DNxHD MXF file in your Av
id Bin and choose export and select ‘QuickTime Movie’
and choose ‘Same as Source’ and check ‘Use Avid Codecs’ – using those settings for exporting will simply rewrap the
DNxHD MXF file as a DNxHD MOV file without converting the actual DNxHD data.
There’s also another option we have to set before exporting from Avid MC – it’s the ‘Color Levels’ option and the two
options are
(a) ‘RGB’
(b) ‘601/709’
The above options will not convert the DNxHD data; rather it’s a setting for the Avid QuickTime Codecs that gets
embedded in the MOV file wrapper. The above setting will tell the Avid QuickTime Codecs how to convert the DNxHD to
RGB, if RGB is requested by
an application. So if you had selected the ‘601/709’ Color Level on export the DNxHD MOV
file then anytime DNxHD is converted to RGB by the codecs it will be SMPTE RGB, and likewise for the ‘RGB’ Color Level
setting.
We believe that Avid MC gives this option on exporting DNxHD MOV files because Avid realizes that not all applications
work with SMPTE RGB and this setting enables users to work with DNxHD MOV files at Full Range RGB in those
applications.
Please note that Avid did introduce a new DNxHD444 RGB format in Avid MC 6. This flavor of DNxHD is not compressed
from YUV data like the other flavors of DNxHD, but it is compressed from RGB data. The above ‘Color Level’ settings still
seem to apply on whether the DNxHD444 is decompressed to SMPTE RGB or Full Range RGB.
Overview of the Avid QuickTime Codecs
The reason why we discussed how to export DNxHD MOV files from Avid MC is because Calibrated{Q} MXF Import is a
QuickTime Import component that enables supported applications to ‘open’ and ‘use’ a MXF file like a MOV file. However,
the actual video in MXF files is decoded by the appropriate QuickTime Video codecs installed on your computer. So when
Calibrated{Q} MXF Import opens a DNxHD MXF file
– the actual DNxHD data in the MXF file will be decoded by the Avid
QuickTime Codecs installed on the computer.
Per our research
– the Avid QuickTime codecs support decoding to 16/8-bit RGB(A) 444(4), 8-bit YUV422, and two other
‘special’ 8-bit YUV444 formats that mainly are only used in Final Cut Pro or Final Cut Studio applications.
When the Avid QuickTime Codecs are converting YUV<->RGB the embedded Color Level setting in the DNxHD MOV file
lets the Avid QuickTime Codecs know whether to use SMPTE RGB or Full Range RGB.
The actual DNxHD MXF files do not have
this embedded ‘tag’ in the MXF file, but because Calibrated{Q} MXF Import
uses the Avid QuickTime Codecs to decode the DNxHD data in MXF files then Calibrated{Q} MXF Import must also