Method and apparatus for converting analog video signal to digital video signal

A method for removing flicker from a luminance component of a video signal, comprising the steps of:

• storing a first video scan line of the video signal in a first line store;
• storing in parallel a second immediately following video scan line of the video signal in a second line store without the second scan line first being stored in the first line store;
• and
• forming a weighted sum of the stored video scan lines and a third video scan line immediately prior to the first video scan line.

A video color subcarrier signal generator, comprising:

• a phase locked loop driven by a horizontal line synchronizing signal of a video signal;
• a scaler driven by the phase locked loop and by a reference clock signal;
• and
• a digital frequency synthesizer having two input terminals, a first input terminal being coupled to a pixel clock signal output by the phase locked loop and a second input terminal being connected to the scaler, the digital frequency synthesizer providing the color sub-carrier signal at its output terminal.

A method of generating a video color sub-carrier signal, comprising the steps of:

• generating a pixel clock signal from a horizontal line synchronizing signal of a video signal;
• determining any frequency error in the pixel clock signal from a reference clock signal;
• and
• digitally synthesizing the color sub-carrier signal from the pixel clock signal and the frequency error.

A method for converting an analog video signal to a digital video signal, comprising the steps of:

• sampling the analog video signal at a time when a level of the analog video signal is not changing;
• comparing the sampled analog signal to each of a plurality of N values;
• and
• converting the compared values to a digital signal having less than N bits.

An analog to digital converter for video signal, comprising:

• a sample and hold circuit coupled to receive an analog video signal, and having a clock terminal and an output terminal;
• a plurality of comparators coupled in parallel to the output terminal of the sample and hold circuit;
• a digital converter coupled in a parallel to output terminals of the comparators;
• and
• a logic gate having its output terminal coupled to the clock terminal of the sample and hold circuit and having a first input terminal coupled to an input clock signal and a second input terminal coupled to a signal controlling a phase of the input clock signal.

A video signal converter for converting RGB non-interlaced video to composite video, comprising:

• three analog to digital converters, each receiving at an input terminal one of the R, G, and B video signals;
• a converter circuit coupled to receive digitized R, G and B signals from the analog to digital converter and converting the R, G, and B digitized signals to YCbCr component video;
• a flicker filter coupled to the converter circuit to receive the YCbCr video components from the converter circuit and to remove flicker from the YCbCr components;
• an interlacer coupled to the flicker filter to interlace a signal output from the flicker filter;
• a digital video encoder coupled to receive the interlaced signal from the interlacer circuit;
• and
• at least one digital to analog converter coupled to the digital video encoder to output a composite video signal.