Patent ID: 7355653

Claim:
A video signal processing circuit is characterized by comprising: analog/digital converting means for inputting a composite video signal of a first system with a first color burst signal frequency, said first system and said first color burst signal frequency being different than a second system having a second color burst signal frequency, and for converting an inputted analog composite video signal to a digital composite video signal by sampling with a sampling frequency in accordance with a system clock; video signal processing means for executing a YC separation process for separating a luminance signal and a chroma signal from said digital composite video signal and for executing a chroma demodulation process for demodulating said chroma signal obtained by said YC separation process, at a predetermined timing based on said system clock; and system clock generating means for generating said system clock synchronized with a color burst signal extracted from said digital composite video signal, and configured to change and set a coefficient n in accordance with a system of said composite video signal inputted to said video signal processing means such that the coefficient n corresponding to said first system, n 1 , is different from the coefficient n corresponding to said second system, n 2 , the product of the color burst signal frequency (fsc) of said first system and n 1 being substantially equal to a frequency m, and the product of the fsc of said second system and n 2 being substantially equal to said frequency m, the system clock frequency being set to m.