#define kMovieLengthInSeconds   10    // the length of our data in seconds

#define kVideoSampleRate        3000  // 30 frames per second

#define kVideoFrameDuration     100

#define kVideoFrameHeight       120L

#define kVideoFrameWidth        160L

// the structure that stores information we want passed to the app-defined

// procedure that generates video data

// a pointer to this struct is pass to MovieExportAddDataSource as the refCon

typedef struct {

  GWorldPtr              fGWorld;

  long                   fTrackID;

  long                   fDataSize;

  ImageDescriptionHandle fImageDescription;

} VideoDataRec, *VideoDataRecPtr;

static pascal OSErr My_VideoDataProc(void *inRefCon, MovieExportGetDataParams *inParams)

{

  CGrafPtr         myOldPort;

  GDHandle         myOldDevice;

  Rect             myRect;

  Str255           myString;

  static long      myFrameNum = 0;

  VideoDataRecPtr  myVideoDataRecPtr = (VideoDataRecPtr)inRefCon;

  if (NULL == myVideoDataRecPtr) return paramErr;

  // end the data after desired length of movie

  if (inParams->requestedTime >

       kVideoSampleRate * kMovieLengthInSeconds) return eofErr;

  // set the size of the video frame

  MacSetRect(&myRect, 0, 0, kVideoFrameWidth, kVideoFrameHeight);

  // if we haven't allocated a GWorld yet do it now

  // this is our "source" for the video frame

  if (NULL == myVideoDataRecPtr->fGWorld) {

      PixMapHandle myPixMap = NULL;

      OSErr        myErr = noErr;

      QTNewGWorld(&(myVideoDataRecPtr->fGWorld), k32ARGBPixelFormat,

                   &myRect, NULL, NULL, 0);

    if (NULL == myVideoDataRecPtr->fGWorld) return memFullErr;

    // grab the pixmap and create the ImageDescription

    myPixMap = GetGWorldPixMap(myVideoDataRecPtr->fGWorld);

    if (NULL == myPixMap) return memFullErr;

    LockPixels(myPixMap);

    // creates an Image Description for our "source" PixMap

    // MakeImageDescriptionForPixMap fills in the dataSize parameter of the

    // ImageDescription structure with the correct value

    myErr = MakeImageDescriptionForPixMap(myPixMap,

                                          &(myVideoDataRecPtr->fImageDescription));

    if (noErr != myErr) return myErr;

    myVideoDataRecPtr->fDataSize = (**(myVideoDataRecPtr->fImageDescription)).dataSize;

  }

  GetGWorld(&myOldPort, &myOldDevice);

  SetGWorld(myVideoDataRecPtr->fGWorld, NULL);

  // draw a frame:

  // white rectangle with black frame number centered horizontally in frame

  EraseRect(&myRect);

  ForeColor(whiteColor);

  PaintRect(&myRect);

  ForeColor(blackColor);

  NumToString(++myFrameNum, myString);

  MoveTo((short)(myRect.right / 2) - (StringWidth(myString) / 2),

         (short)(myRect.bottom / 2));

  TextSize((short)(myRect.bottom / 4));

  DrawString(myString);

  // fill in the MovieExportGetDataParams for QuickTime

  inParams->actualTime = inParams->requestedTime;

  inParams->dataPtr = GetPixBaseAddr(GetGWorldPixMap(myVideoDataRecPtr->fGWorld));

  // we know the dataSize is correct as MakeImageDescriptionForPixMap

  // supplied this value

  inParams->dataSize = myVideoDataRecPtr->fDataSize;

  inParams->desc = (SampleDescriptionHandle)(myVideoDataRecPtr->fImageDescription);

  inParams->descType = VideoMediaType;

  inParams->descSeed = 1;

  inParams->actualSampleCount = 1;

  inParams->durationPerSample = kVideoFrameDuration;

  inParams->sampleFlags = 0L; // sync sample

  // restore the original graphics port and device

  SetGWorld(myOldPort, myOldDevice);

  return noErr;

}