A DirectDrawVideoPort object represents the video-port hardware found on some display adapters. Generally, a video-port object controls how the video-port hardware applies a video signal it receives from a video decoder directly to the frame buffer.
More than one channel of video can be controlled by creating as many DirectDrawVideoPort objects as is required. Because each channel can be separately enumerated and configured, the video hardware for each channel does not need to be identical.
For more information, see Video-Port Technology Overview.