Overlaying Video Tracks
When
one video track is drawn on top of
another, the top doesn’t necessarily have to obscure
the bottom. QuickTime gives you the option of specifying a
GraphicsMode
to combine pixels from multiple video
layers to create interesting effects.
How do I do that?
You can create a
GraphicsMode
object to describe the means of
combining overlapping colors. To try it out, take the previous
lab’s code and replace all the matrix stuff (after
the foreTrack
and backTrack
are
created, but before the MovieController
is
created) with the following:
GraphicsMode gm = new GraphicsMode (QDConstants.addMax, QDColor.green); VisualMediaHandler foreHandler = (VisualMediaHandler) foreTrack.getMedia( ).getHandler( ); foreHandler.setGraphicsMode(gm); foreTrack.setLayer(-1);
Note
Run this example with ant run-ch08-composit-evideotracks.
When run, this sample program asks you to open two movies, then creates a new movie with video tracks from the source movies’ media, and combines the pixels of the foreground movie with the background, so the foreground appears atop the background. The result is shown in Figure 8-4.
Figure 8-4. Composited video tracks with addMax graphics mode
What just happened?
Setting a GraphicsMode
instructs QuickTime to
apply a specific behavior to combine overlapping pixels. The
GraphicsMode
has a
“mode” int
,
which indicates which kind of behavior to use, and a
QDColor ...
Get QuickTime for Java: A Developer's Notebook now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.