Apple DVD Studio Pro 4 - Manual (Page 118)

Important: When the alpha channel is embedded with the asset movie, be sure the video
output is premultiplied.
Switch Points
If your transition does not require the start and end frame video to be on the screen at
the same time, you can add a switch point marker to the asset movie to control when
the transition switches from showing the start frame to showing the end frame. If you
do want to have both the start and end frame video on the screen at the same time, you
must use a background matte movie (described in
Background Matte Movie ).
If the transition asset folder does not contain a background matte movie, DVD Studio Pro
does the following to set the switch point:
• DVD Studio Pro first looks in the asset movie to see if it includes a marker named
TransitionSwitchPoint. If present, this marker is used as the switch point.
• If not present, DVD Studio Pro looks to see if there are any markers in the asset movie.
If present, the first marker is used as the switch point.
• If no markers are present in the asset movie, the switch point is set to the asset movie’s
halfway point.
Asset Matte Movie
The asset matte movie is required only when an asset movie that does not include an
alpha channel is used by the transition. Having a separate asset matte movie is particularly
useful when the asset movie is normal video (as opposed to an animation).
The asset matte movie must have the same name as the transition asset folder, followed
by “-matte” and can have an extension. For example, if the transition asset folder’s name
is Spinning DVD, the asset matte movie could be named Spinning DVD-matte.mov.
The white areas define
where the asset movie
video appears.
The black areas define
where the background
video (start or end frame,
depending on the switch
point or background
matte movie) appears.
The gray areas define
where the asset movie
video appears, but
is transparent.
118 Chapter 8 Preparing Alpha Transitions