If the same hardware is required or used for a combination of video capture and video compression, you might combine both of these functions into a common DLL and use a single DriverProc entry point to service them. The common entry point will simplify the coordination of the different functions.
Note Because video capture drivers can rely on video compression and decompression drivers for efficient operation, a single driver can handle both video capture, and video compression and decompression services. Video capture drivers use the VIDEO_OPEN_PARMS data structure when they are opened. This structure has the same member definitions as the ICOPEN structure used by video compression and decompression drivers. By examining the fccType member, a combined driver can determine whether it is being opened as a video capture driver or a video compression and decompression driver. (Video capture devices contain the four-character code 'vcap' in this member.) For more information on video compression and decompression drivers, see Video Compression and Decompression Drivers.