Technical Q&A QTMTB58

BeginMediaEdits -2050 badDataRefIndex error after calling NewMovie

Q: I have created a movie with the NewMovie function. After adding the tracks and the media using the NewMovieTrack and NewTrackMedia functions, I'm calling BeginMediaEdits to start a media editing session. However, BeginMediaEdits returns the -2050 badDataRefIndex error code. I have checked the movie, track and media, and all are valid. What am I doing wrong?

A: What's happening is when you create a movie from "nothing," as with NewMovie, the movie does not have a containing data reference (for example, if you call NewMovieFromFile, the containing data reference is an alias to the movie file on disk). Therefore, when you attempt to add sample data to the media with BeginMediaEdits, QuickTime can't do this because there's no data reference. You can solve this problem by specifying a data reference when you create your media with the NewTrackMedia function. In the sample below, we show how to create a handle data reference (you can get away with specifying a 0-length handle for the reference). Now, when BeginMediaEdits is called to begin the media editing session, QuickTime will have a data reference to write data to:

OSType    dataRefType;
Handle    dataRef = nil;
Handle    hMovieData = NewHandle(0);

// Construct the Handle data reference
err = PtrToHand( &hMovieData, &dataRef, sizeof(Handle));

theMedia = NewTrackMedia (theTrack,
                          VideoMediaType,
                          600, // pass an appropriate time scale
                               // for your media here
                          dataRef,
                          HandleDataHandlerSubType);
.
.
.
// clean up when we are done with the
// media editing session
DisposeHandle(hMovieData);
DisposeHandle(dataRef);

[Sep 05 2000]