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Demystifying the Avid Import Settings Dialog Box: Part 2

Ashley Kennedy

Import images into Avid Media Composer the right way!  Master these simple rules to make importing as accurate and effective as possible.

(Part 2)

Importing graphics and movies into editing software isn’t always as cut and dry as it might seem.  Indeed, you have many choices regarding size, aspect ratio, pixel shape, color, and alpha channel treatment — and if you make just one wrong choice, your graphic may come in unrecognizable.  For that reason, it’s a good idea to master the rules in Avid Media Composer’s Import Settings dialog box.

This is the second post in a two-part series concerning the various settings in the Import Settings dialog box in Avid Media Composer.  This post will explain the following categories:

  • File Pixel to Video Mapping
  • Frame Import Duration
  • Autodetect Sequentially-Numbered Files
  • Field Ordering in File
  • Alpha Channel

Let’s go section by section in the bottom-half of the window, and talk about what everything means.  (For an explanation of the Image Size Adjustment settings, see Part 1 of this series.)

File Pixel to Video Mapping

This section explains how Avid Media Composer treats imported files in terms of luma levels — specifically at the extreme ends (video black and video white).

  • Computer RGB (0-255):  Choose this option for traditional computer graphics that use RGB graphic levels.  (This includes pretty much any computer generated graphics.)  Upon import, the blackest black in the image is assigned to the value of video black, and the whitest white is assigned the value of video white.  This brings all values within the acceptable (legal) video signal range.
  • Computer RGB, dither image colors:  This option assigns video black and video white values as outlined above.  However, if you import an image with a fine gradient, sometimes the graphic exhibits a certain amount of “banding” where like colors can clump together.  If you see this happen, you can choose this option, which will add a slight amount of video noise to the gradient.  This can thus hide the banding and make the entire image look smoother.  (Note: Only choose this option if you first notice the banding upon import; don’t guess or anticipate that the banding might occur.)
  • 601 SD or 709 HD (16-235): This option does not clip the image at video black or video white.  Therefore, choose this option if the graphic you’re importing was created specifically to exceed the standard SD or HD video signal range.  This includes things like color bars or images that include superblack for keying purposes.  (Do not choose this option if the graphic isn’t being used for reasons like this, or illegal luma and chroma levels may result.)

Frame Import Duration

This one is easy; the number you input here determines how many seconds that still graphics will be once they are imported into Avid Media Composer.

Autodetect Sequentially-Numbered Files

You should check this box when importing multi-file animations.  (Leave it unchecked when importing single graphics.)

So basically, if you check this box when selecting the first in a series of numbered files (which usually have been generated from a graphics creation program like Adobe After Effects), then Avid Media Composer will bring all sequentially-numbered files in order, thus combining many files to produce a single animation file.

Field Ordering in File

This option controls the field ordering, or field dominance of the material you import for interlaced footage.  If you’re working in a progressive project (i.e., 23,976p, 24p, etc.), this category is not displayed in the Import Settings Dialog box.

Here’s a little cheat sheet on field ordering:
•  NTSC (Standard and DV): Even (Lower Field First)
•  PAL (Standard): Odd (Upper Field First)
•  PAL (DV): Even (Lower Field First)
•  HD: Odd (Upper Field First)

So, given those characteristics, here are the rules for import:

  • Ordered for Current format:  You choose this option when the imported file is correctly field ordered with respect to the project field order.
  • Odd (upper-field first) ordered:  You choose this option if the file is odd ordered and you are importing it into an even ordered project format.
  • Even (lower-field first) ordered:  You choose this option if the file is even ordered and you are importing it into an odd ordered project format.

So for example, if you are importing an HD graphic into an HD project, you would choose “Ordered for Current format.”  But if you are importing an NTSC graphic into an HD project, you would choose “Even (lower-field first) ordered.”

Alpha Channel

The rules for Avid Media Composer’s treatment of alpha channel information is as follows:
•  White background — the transparent “alpha” layer
•  Black foreground — the opaque “object” layer
•  Gray transparency blend between the two

So, given the above information, here’s what these options mean:

Invert on import (white = opaque):  When you choose this option, the existing alpha channel information is reversed on import.   You should almost always choose this option, as pretty much every graphics creation program out there exhibits alpha channels with the white part of the image being opaque, and the black part of the image being transparent.  Therefore, when you invert these on import, Avid Media Composer reads them “correctly.”

Do not invert (black = opaque): When you choose this option, the existing alpha channel information is used.  You don’t use this option very often.

Ignore: If you check this option, an image that contains alpha channel information just comes in as one opaque graphic — except the alpha channel information is disregarded, and only the RGB information is used.  The resulting imported graphic appears as a single master clip in the bin, rather than as a Matte Key.