Apple Shake 4 - Manual (Page 216)

216 Chapter 6 Importing Video and Anamorphic Film
The correct way to account for video pixel ratios is to use the viewerAspectRatio
parameter (within the format subtree of the Globals tab) to set the aspect ratio of the
Viewer, leaving the fields of your video frames untouched. This also only affects the
Viewer—rendered images are not affected. However, Viewer playback performance
may be slightly affected.
You need only to change the defaultAspect for proper rendering. Unlike using the
proxyRatio method, you set defaultAspect to 1/YourVideoAspectRatio. For example, PAL
HD uses 1.422 as its aspect ratio. Therefore, set viewerAspectRatio to 1.422, and
defaultAspect to 1/1.422. Shake resolves the expression of 1 divided by 1.422 to become
0.703235. All other principles of image manipulation apply.
Table of Common Aspect Ratios
Below is a table of common aspect ratios, containing the values you should assign to
specific parameters. For nodes, the aspectRatio parameter is taken from the
defaultAspect value at the time the node is created. It is not changed if you later
change the defaultAspect.
Additionally, RGrad is the inverse of the other aspectRatio parameters, for example, 1/
defaultAspect, which accounts for its own column in the table. Initially setting the
defaultAspect guarantees that all nodes automatically get the proper aspect ratio.
Finally, follow the guidelines in Chapter 14, “ Customizing Shake ,” and save your
interface settings to preserve default values for these parameters. For more
information, see “
Customizing Interface Controls in Shake ” on page 359.
Preset Formats
The format pop-up menu in the Globals tab provides a number of preset formats. You
can also create your own formats.
Format
aspect
Ratio proxy
Ratio
Viewer
Aspect
Ratio
default
Aspect
aspect Ratio
(common
nodes) aspect
Ratio
(RGrad)
2:1
Anamorphic
Film 2 .5 NA .5 .5 2
4:3 NTSC D1
720 x 486,
720 x 480 .9 NA .9 1/.9 = 1.1111 1.11111 .9
16:9 NTSC
720 x 486 1.2 NA 1.2 1/1.2 =
.83333 .8333 1.2
4:3 PAL D1
720 x 576 1.066 NA 1.06 1/1.066 =
0.938086 0.938086 1.066
16:9 PAL
720 x 576 1.422 NA 1.422 1/1.422 .703235 1.422