Converter to convert a computer graphics signal to an interlaced video signal

A non-interlaced to interlaced video signal converter comprising:

• an input for receiving a digital video input signal at a first line rate;
• three one-line stores each coupled to said input to receive lines of said digital video signal;
• averaging means coupled to the outputs of said three one-line stores to generate a weighted average therefrom;
• and
• control means for controlling the writing of lines of said digital video input signal into said stores and the reading from said stores to said averaging means, said control means causing said lines of said digital video input signal to be applied to said stores at a first rate and in the sequence A,B,C,B,A . . . , and causing lines to be read from said stores simultaneously at a second rate which is substantially half said first rate.

A converter for converting a computer graphics signal into a video signal, comprising:

• receiving means for receiving an input computer graphics signal in the form of a VGA 640.times.480 mode non-interlaced signal;
• and
• converting means coupled to said receiving means for converting said non-interlaced signal to an interlaced signal with half the number of lines per field;
• said converting means comprising:
• a plurality of line stores coupled to receive lines of said non-interlaced signal at a first line rate and to output an output signal at a second line rate which is half said first line rate, each said line store being a first-in first-out (FIFO) store and having a data input, a data output, a write clock input and a read clock input, and each said line store being capable of receiving data at said data input in response to write clock pulses received at said write clock input, and simultaneously, outputting data at said data output in response to read clock pulses received at said read clock input;
• and
• means coupled to said data outputs of said line stores for providing an output video signal formed of an average of said output signals from said line stores so as to apply a filter function to said output signals from said line stores to generate said output video signal.

A process for converting a computer graphics signal into a video signal, comprising the steps of:

• receiving an input computer graphics signal in the form of a VGA 640.times.480 mode non-interlaced signal;
• and
• converting said non-interlaced signal to an interlaced signal with half the number of lines per field, said converting step comprising:
• providing a plurality of line stores, each said line store being a first-in first-out (FIFO) store having a data input, a data output, a write clock input, and a read clock input;
• applying input lines of said input computer graphics signal sequentially to said line stores at a first line rate;
• applying write clock pulses to an individual line store to enter input line data into said line store and, simultaneously, applying read clock pulses to said individual line store to output data from said data output of said individual line store;
• and
• forming an average of said output signals from said line stores so that a filter function is applied to said output signals from said line stores to generate an output video signal having a second line rate, said second line rate being half said first line rate.