Video interface systems for displaying input video signals from different types of video sources are known. While many characteristics of video signals vary in accordance with the particular source, common video signal attributes are Horizontal SYNC, or HSYNC, pulses which define the end of a line and Vertical SYNC, or VSYNC, pulses which define the end of a field.
Generally, video interface systems include a memory table containing a list of known video source names and a set of characteristics associated with each known video source. When a video signal is received, one or perhaps a few characteristics of the video signal are measured and compared to the sets of characteristics stored in memory. If the measured characteristics match a set of characteristics stored in memory, then the input video signal is determined to be provided by the video source associated with the matching set of characteristics. Thereafter, the measured characteristics are discarded and the prestored control parameters for that source are used to process and display the input video signal.
The memory table storing known video source names and associated sets of characteristics is limited both by the number of known video sources and the amount of available memory. If either of these factors results in the omission of a particular video source from the table (i.e., if a video signal is received from an "unknown" source), then the system has no way of processing and displaying the signal.