Inside Macintosh: QuickTime Components
You can control digitization on a frame-by-frame basis in your application. The VDGrabOneFrame function (described on VDGrabOneFrame ) digitizes a single video frame. All video digitizer components support this function.
Alternatively, you can use the VDSetPlayThruOnOff function (described on VDSetPlayThruOnOff ) to enable or disable digitization. When digitization is enabled, the video digitizer component places video into the specified destination continuously. The application stops the digitizer by disabling digitization. This function can be used with both destination options. However, not all video digitizer components support this function.