QuickTime for Java: A Developer's Notebook

Exporting Movies to Any Installed Format

Exporting to a list of known formats is limiting—if the end user has installed new movie exporters, either from third parties or via an update to QuickTime itself, a program that uses a canned list of exporters won’t be able to pick them up. Fortunately, QuickTime provides a means of querying for installed components of a given type. You can use this strategy to offer a list of all available exporters.

How do I do that?

The AdvancedMovieExport eliminates the three canned entries in the choices array that were used by SimpleMovieExport (shown in Example 4-2) and instead builds the array through a process of discovery; this code would replace the short “build choices” block in the constructor for SimpleMovieExport but needs to go inside the try-catch, because it makes calls that can throw QTException:

Vector choices = new Vector( );
ComponentIdentifier ci = null;
ComponentDescription cd =
  new ComponentDescription(StdQTConstants.movieExportType);
while ( (ci = ComponentIdentifier.find(ci, cd)) != null) {
  // check to see that the movie can be exported
  // with this component (this throws some obnoxious
  // exceptions, maybe a bit expensive?)
  try {
      MovieExporter exporter = new MovieExporter (ci);
      if (exporter.validate (movie, null)) {
          ExportChoice choice =
              new ExportChoice (ci.getInfo( ).getName( ),
                                ci);
          choices.addElement(choice);
      }
  } catch (StdQTException expE) {
      System.out.println ("** can't validate " +
                          ci.getInfo( ).getName( ) + " **");

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