Converter to convert a computer graphics signal to an interlaced video signal
First Claim
1. 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×
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;
three line stores A, B, C 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;
means coupled to the outputs of said three line stores for providing a weighted average of said output signals from said line stores; and
means for causing input lines to be applied to said line stores in the sequence A, B, C, B, A . . . .
2 Assignments
0 Petitions
Accused Products
Abstract
A converter receives a computer graphics signal from a PC and provides from it a video signal for display or recording. Analogue RGB signals are digitised and applied to a vertical filter and rate buffer. The rate buffer needs only one to three lines of storage capacity. The received graphics signal is a VGA 640×480 non-interlaced mode signal, and the rate buffer halves the line rate and produces an interlaced output. Such a signal can be treated as a video signal, after reconversion to analogue form. The vertical filter provides a degree of vertical averaging to remove flicker. In a preferred store using three line-store FIFOs, input lines are applied to them in the sequence A,B,C,B,A, and so on.
46 Citations
13 Claims
-
1. 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×
480 mode non-interlaced signal; andconverting 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;three line stores A, B, C 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; means coupled to the outputs of said three line stores for providing a weighted average of said output signals from said line stores; and means for causing input lines to be applied to said line stores in the sequence A, B, C, B, A . . . . - View Dependent Claims (2, 3, 4, 5)
-
-
6. In a personal computer system comprising a personal computer having a microprocessor and a video output, said video output being capable of providing a non-interlaced graphics signal in VGA 640×
- 480 mode, and a video monitor for displaying a graphics image in response to said graphics signal, a converter circuit, said converter circuit comprising;
input means for connection to said video output of said personal computer; first output means coupled to said input means for connection to said video monitor; converting means coupled to said input means for converting said non-interlaced graphics signal to an interlaced signal with half the number of lines per field and each line having double the line duration, said converting means comprising three 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 means for causing successive input lines to be stored in said line stores in the sequence A, B, C, B, A . . . . - View Dependent Claims (7, 8, 9, 10)
- 480 mode, and a video monitor for displaying a graphics image in response to said graphics signal, a converter circuit, said converter circuit comprising;
-
11. 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.
-
-
12. 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×
480 mode non-interlaced signal; andconverting 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.
-
-
13. 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×
480 mode non-interlaced signal; andconverting 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.
-
Specification