An apparatus and method for automatically detecting a display mode to be used
in a serial data interface (SDI) of a decoded video signal is provided. The apparatus
for detecting a display mode includes a mode detector which detects a predetermined
display mode by counting clock pulses generated between a present horizontal synchronous
signal and a next horizontal synchronous signal from input decoded video signals,
and a signal processing unit which converts formats of the decoded video signals
so as to correspond to a display mode detected by the mode detector, serializes
and outputs the decoded video signal. By deleting a control signal indicating a
display mode, a control signal that does not coincide with processed data as a
result of an incorrectly or incompatibly designed controller can be prevented.
