This page contains information that you should know before creating AAF/MXF file using the options on the Render Pass Property Editor.
About MXF Media Files and the AAF Master Clip
MXF (Material Exchange Format) is an industry-standard container format that encapsulates media and production metadata into a single file. MXF is supported as a common file format in a wide variety of Avid editing applications including Avid 3D. MXF files replace OMFI media files.
MXF media files are video files, similar to AVI or QuickTime movies, and can be used on their own. However, they are not directly seen by users but instead are referenced by master clips and managed by an Avid editing application.
AAF (Advanced Authoring Format) is a cross-platform, multimedia file format that allows interchange of composition information between AAF-compliant applications. AAF replaces OMFI compositions.
The purpose of the AAF file is to present the media files as a higher-level named clip for the destination application.
AAF Naming, Location, and Auto-Import
You can create the AAF master clip in any location and import it into Avid editing applications.
In the Avid editor, if the current Avid project has a bin named “Avid3D InComing”, the application automatically imports AAF files found in a special directory named “Avid3D OutGoing”, either on startup or when switching between applications.
The “Avid3D OutGoing” directory must be located in the root of a local drive. By default, XSI creates AAF files in the D:\Avid3D OutGoing directory, and will create the directory automatically if it doesn’t exist.
Both the bin name and the directory name must have proper spacing and Capitalization for AAF Auto-Import to work correctly. Please verify your editing application's documentation for AAF Auto-Import support.
MXF Naming and Location
Media files are usually put on a high performance hard disk for real-time playback in the destination editing application. XSI always creates the MXF media files in the \Avid MediaFiles\VideoStorage\Avid3D folder on the selected media drive. If the directory doesn’t exist, XSI creates it automatically.
The absolute path to the MXF Media Files is stored inside the AAF Master Clip. If the MXF files are produced on a different machine and moved onto the machine on which the Avid editing application is installed, they must be available from the same path on the same drive letter.
For example, if the media drive is D: in XSI, when the AAF is created, and the AAF and MXF files are copied over to an Avid machine, the MXF files must be found on the D: drive, under the same directory tree structure. The AAF file itself can be located anywhere.
XSI automatically generates a unique name for an MXF media file by combining the clip name and a globally unique identifier (GUID). It is not possible to explicitly name the MXF files. New MXF files are created every time the clip is re-rendered. Existing MXF files are never replaced, and their names will never conflict other media files.
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It is up to you to explicitly purge unused media files once they are no longer used by any sequence or clip. In Avid editing products, this is done with the “Media Tool.” MXF files produced in XSI or are managed the same way as media captured directly in Avid editing applications. |
MXF media files are video material and therefore do not contain the alpha information an RGBA image sequence provides. If you export alpha information for compositing, two MXF files are produced, one for the color track and the other for the alpha. The AAF master clip will contain a simple composition with a “Matte Key” effect that recombines these two media files in the destination application.
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MXF files are created in the YCbCr601 color space or YCbCr709 for high-definition files. |
Setting Camera and Field Rendering Options for AAF/MXF
MXF media files are created to be ready for real-time video playback in the destination editing application. Several compression codecs are offered, including DV50 and Avid’s High-Definition HD codecs—DNxHD.
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For more information about DNxHD codecs, visit the Avid website at http://www.avid.com/DNxHD. All internet addresses have been checked prior to publication. However, because of the transient nature of the Internet, they may no longer be valid. |
Setting Camera Options
When you create AAF/MXF files, the render pass camera must be set to the image size the destination application expects. You should use one of XSI’s camera presets: NTSC D1 (720x486) or PAL D1 (720x576) for standard definition, and HD 1080 16/9 (1928x1080) or HD 720 16/9 (1280x720) for high definition. Other sizes are not presently supported. The pixel aspect ratio should be set to the default.
Setting Field Rendering Options
You can use field rendering for smoother motion in NTSC, PAL or 1080i. The destination application for the AAF file generally ignores information about whether or not XSI rendered the sequence in fields. However, you should make sure to use the field order expected by the destination format.
The options for the Field Order setting on the Fields and Script tab of the Render Options property editor correctly identify the required field order for NTSC, PAL, DV or HD. If Field Order is set to Lower Field First / Even (NTSC and DV Format), XSI always creates correct NTSC files, regardless of whether the destination application has the reverse meaning for “Odd” and “Even”.
SOFTIMAGE|XSI v.7.0