Supporting Progressive Downloads

The Movie Toolbox includes functions for supporting progressive downloads of movies. These functions are illustrated in the following sections.

Displaying a Progressively Downloaded Movie

Listing 18 illustrates how to use the QTMovieNeedsTimeTable function to find out if a movie if being progressively downloaded and the GetMaxLoadedTimeInMovie function to find out how much of the movie has been downloaded.

Listing 18Displaying a progressively downloaded movie



 
WindowPtr   movieWindow;

Movie       theMovie;

Boolean     needsTimeTable;

TimeValue   loadedTime = -1;



err = GetDisplayedMovie (&movieWindow, &theMovie);

if (err) goto bail;

err = QTMovieNeedsTimeTable (theMovie, &needsTimeTable);

if (err) goto bail;



if (needsTimeTable)

{

    err = GetMaxLoadedTimeInMovie (theMovie, &loadedTime);

    // Display the movie up to the current end

}

Creating a Track Time Table

Listing 19 illustrates how to use the MakeTrackTimeTable function to create a time table for the tracks in a movie.

Listing 19 Creating a time table for movie tracks



 
OSErr       theErr = noErr;

WindowPtr   movieWindow = nil;

Movie       theMovie = nil;

Track       theTrack;

long        trackCount,

            trackIndex,

            retDataRefSkew;

TimeValue   startTime,

            endTime,

            timeIncrement;

short       firstDataRefIndex,

            lastDataRefIndex;

                    

Handle      offsets,

            offsetsSet [32];



err = GetDisplayedMovie (&movieWindow, &theMovie);

if (err) goto bail;



timeIncrement = GetMovieTimeScale (theMovie);

firstDataRefIndex = -1;

lastDataRefIndex = -1;

trackCount = GetMovieTrackCount (theMovie);



for (trackIndex = 1; trackIndex <= trackCount; trackIndex++)

{

    theTrack = GetMovieIndTrack (theMovie, trackIndex);

    offsets = NewHandle (0);

    offsetsSet [trackIndex - 1] = offsets;

    startTime = GetTrackOffset (theTrack);

    endTime = GetTrackDuration (theTrack);

    err = MakeTrackTimeTable (theTrack, (long **) offsets, 

                startTime, endTime, timeIncrement, 

                firstDataRefIndex, lastDataRefIndex, &retDataRefSkew);

    if (err) goto bail;



    // check data

    }

    

for (trackIndex = 1; trackIndex <= trackCount; trackIndex++)

{

    DisposeHandle (offsetsSet [trackIndex - 1]);

}

Creating a Media Time Table

Listing 20 illustrates how to use the MakeMediaTimeTable function to create a time table for media.

Listing 20 Creating a time table for media



 
OSErr       theErr = noErr;

WindowPtr   movieWindow = nil;

Movie       theMovie = nil;

Track       theTrack;

Media       theMedia;

long        trackCount,

            trackIndex,

            retDataRefSkew;

TimeValue   startTime,

            endTime,

            timeIncrement;

short       firstDataRefIndex,

            lastDataRefIndex;

Handle      offsets,

            offsetsSet [32];



err = GetDisplayedMovie (&movieWindow, &theMovie);

if (err) goto bail;



firstDataRefIndex = -1;

lastDataRefIndex = -1;

        

trackCount = GetMovieTrackCount (theMovie);

            

for (trackIndex = 1; trackIndex <= trackCount; trackIndex++)

{

    theTrack = GetMovieIndTrack (theMovie, trackIndex);

    theMedia = GetTrackMedia (theTrack);

    offsets = NewHandle (0);

    offsetsSet [trackIndex - 1] = offsets;

    startTime = GetTrackOffset (theTrack);

    startTime = TrackTimeToMediaTime (startTime, theTrack);

    endTime = GetTrackDuration (theTrack);

    endTime = TrackTimeToMediaTime (endTime, theTrack);

    timeIncrement = GetMediaTimeScale (theMedia);

    err = MakeMediaTimeTable (theMedia, (long **) offsets, 

                startTime, endTime, timeIncrement, firstDataRefIndex,

                lastDataRefIndex, &retDataRefSkew);

    if (err) goto bail;

    

    // check data

}

    

for (trackIndex = 1; trackIndex <= trackCount; trackIndex++)

{

    DisposeHandle (offsetsSet [trackIndex - 1]);

}