Patent ID: 6545725
Filing Date: 2003-04-08
Classification: H04N

Abstract:
An apparatus for identifying standard and non-standard video signals, comprising:clock generating means for generating a clock of a frequency of aÃ—fSC (a is an integer not less than 1, and fSC is a color carrier frequency) based on a color burst signal extracted from a video signal; clock counting means whose maximum output value is a value corresponding to the number of clocks generated by said clock generating means in one field section of a standard signal, said clock counting means counting the number of clocks generated by said clock generating means, and repetitively changing an output value thereof from zero to the maximum output value; resetting means for resetting a count value of said clock counting means to zero in response to input of an external reset signal, and canceling the reset of the count value of said clock counting means in response to an external vertical synchronizing signal separated from the video signal and input after the input of the external reset signal; count value holding means for holding the count value of said clock counting means in response to the input of the external vertical synchronizing signal; first determining means for comparing an output value of said count value holding means with a first threshold value to thereby determine whether the output value of said count value holding means is zero or a value in the vicinity thereof, or the maximum output value of said clock counting means or a value in the vicinity thereof; subtracting means for obtaining a difference between the output value of said count value holding means and the maximum output value of said clock counting means; selecting means for, based on a result of the determination by said first determining means, selecting the output value of said count value holding means when the output value of said count value holding means is zero or a value in the vicinity thereof, and selecting the output value of said subtracting means when the output value of said count value holding means is the maximum output value of the clock counting means or a value in the vicinity thereof; and second determining means for determining that the video signal is a non-standard signal when an absolute value of an output value of said selecting means is higher than a second threshold value.