Sampling frequency converter, sampling frequency conversion method, video signal processor, and video signal processing method

A video signal processor comprising:

• an A/D converter circuit for sampling an analog video signal on a first clock signal having a first frequency, to be converted into a first digital video signal;
• a synchronous signal separation means for separating a first synchronous signal from the analog video signal;
• a first clock generation means for generating the first clock signal from the first synchronous signal;
• and
• a sampling frequency converter for interpolating the first digital video signal to be converted into a second digital video signal, and outputting the second digital video signal on the basis of a second clock signal having a second frequency,
• said sampling frequency converter comprising:
• a first digital-digital conversion means for interpolating the first digital video signal to calculate a second digital video signal, a length of one horizontal period and a sampling frequency of which signal are the same as those of the first digital video signal and an effective pixel period in one horizontal period of which signal is N times (N>0) as long as that of the first digital video signal, and converting the first digital video signal into the second digital video signal to be output on the basis of the first clock signal;
• a second clock generation means for generating a second clock signal having a second frequency which is one-Nth as high as that of the first clock signal;
• and
• a storage means for retaining the second digital video signal as well as reading the retained second digital video signal on the second clock signal to be output as a third digital video signal.

A sampling frequency conversion method comprising:

• a digital-digital conversion step of receiving a first digital video signal which has been sampled on a first clock signal having a first frequency, interpolating the first digital video signal to calculate a second digital video signal, a length of one horizontal period and a sampling frequency of which signal are the same as those of the first digital video signal and an effective pixel period in one horizontal period of which signal is N times (N>0) as long as that of the first digital video signal, and converting the first digital video signal into the second digital video signal to be output on the basis of the first clock signal;
• a clock generation step of generating a second clock signal having a second frequency which is one-Nth as high as that of the first clock signal;
• and
• a storage step of retaining the second digital video signal as well as reading the retained second digital video signal on the second clock signal to be output as a third digital video signal.

A video signal processing method comprising:

• an A/D conversion step of sampling an analog video signal on a first clock signal having a first frequency to be converted into a first digital video signal;
• a synchronous signal separation step of separating a first synchronous signal from the analog video signal;
• a first clock generation step of generating the first clock signal from the first synchronous signal;
• a first digital-digital conversion step of interpolating the first digital video signal to calculate a second digital video signal, a length of one horizontal period and a sampling frequency of which signal are the same as those of the first digital video signal and an effective pixel period in one horizontal period of which signal is N times (N>0) as long as that of the first digital video signal, and converting the first digital video signal into the second digital video signal to be output on the basis of the first clock signal;
• a second clock generation step of generating a second clock signal having a second frequency which is one-Nth as high as that of the first clock signal;
• and
• a storage step of retaining the second digital video signal as well as reading the retained second digital video signal on the second clock signal to be output as a third digital video signal.