Exporting Data to a PICS File

Inside Macintosh: QuickTime Components

Exporting Data to a PICS File

To export data to a PICS file, your component must

allow the Movie Toolbox to call the MovieExportToFile function in order to export movie data into a file
read the data from the track or movie
perform appropriate conversions on that data
place the data into the specified file (the file's type corresponds to the component subtype of your movie data export component)

Listing 4 provides an implementation of these tasks in a movie export component. The ExportPICSToFile function performs the export operation by opening the resource fork of the PICS file and cycling through the movie time segment, adding a frame to the PICS file.

Listing 4 Exporting a frame of movie data to a PICS file



 
pascal ComponentResult ExportPICSToFile (ExportPICSGlobals store, 

                                            const FSSpec *theFile, 

                                            Movie m, 

                                            Track onlyThisTrack,

                                            TimeValue startTime,

                                            TimeValue duration)

{

    OSErr err = noErr;

    short resRef = 0;

    short saveResRef = CurResFile();

    short resID = 128;

    PicHandle thePict = nil;



 
    /* open the resource fork of the PICS file 

        (the caller is responsible for creating the file) */

    resRef = FSpOpenResFile (theFile, fsRdWrPerm);

    if (err = ResError()) goto bail;



 
    UseResFile(resRef);



 
    /* cycle through the movie time segment you were given */

    while (startTime < duration) {

        Byte c = 0;



 
        if (onlyThisTrack)

            thePict = GetTrackPict (onlyThisTrack, startTime);

        else

            thePict = GetMoviePict(m, startTime);

        if (!thePict) continue;



 
        /* add a frame to the PICS file */

        AddResource ((Handle)thePict, 'PICT', resID++, &c);

        err = ResError();

        WriteResource ((Handle)thePict);

        DetachResource ((Handle)thePict);

        KillPicture (thePict);

        thePict = nil;

        if (err) break;



 
        /* find the time of the next frame */

        do {

            TimeValue nextTime;

            if (onlyThisTrack)

                GetTrackNextInterestingTime (onlyThisTrack,

                                             nextTimeMediaSample, startTime, 

                                             kFix1, &nextTime, nil);

            else {

                OSType mediaType = VisualMediaCharacteristic;



 
                GetMovieNextInterestingTime (m, nextTimeMediaSample, 

                                                        1, &mediaType, 

                                                        startTime, kFix1,

                                                        &nextTime, nil);

            }



 
            if (GetMoviesError ()) goto bail;

            if (nextTime != startTime) {

                startTime = nextTime;

                break;

            }

        } while (++startTime < duration);

    }



 
bail:

    if (thePict) KillPicture (thePict);

    if (resRef) CloseResFile (resRef);

    UseResFile (saveResRef);

    return err;

}