Digital-to-analog video encoder with novel equalization
AssigneeAnalog Devices, Inc.
InventorsBrian P. Murray, Philip A. Curran, Colm J. Prendergast, Timothy J. Cummins
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Abstract
A digital-to-analog video encoder method and apparatus having unique equalization are disclosed. The encoder converts digital video signals into one or more analog video formats using one or more digital-to-analog converters. Equalization is provided to compensate for zero order hold effects of the digital-to-analog converters. Equalization is provided to a luminance signal and/or a chroma signal to equalize RGB, composite video, and super VHS video outputs. Multiplexed digital-to-analog converter inputs allow selection of several output formats.
Claims15
A video encoder comprising:
- a digital video input for receiving a digital video signal;
- a modulator having a color difference input connected to said digital video input and having a chroma signal output for providing a chroma signal;
- a chroma equalization circuit having an input connected to said chroma signal output for receiving said chroma signal and having an equalized chroma output for providing an equalized chroma signal;
- at least one digital-to-analog converter having a digital input connected to said equalized chroma output for receiving said equalized chroma signal and an analog output for providing an analog video output signal;
- said equalization circuit having a response bearing a predetermined relationship to at least one characteristic of a transfer response of said digital-to-analog converter.
A video encoder comprising:
- an input for receiving digital video signals;
- a luminance filter connected to said input for receiving a luminance input signal and having a filter output for providing an equalized luminance signal;
- a video converter having an input connected to said filter output for receiving said equalized luminance signal, said video converter selectively generating and outputing digitized video signals representative of a standard format video signal responsive to said digital video signals and said equalized luminance signal;
- a digital-to-analog converter having an input connected to receive said digitized video signals and an output, said digital-to-analog converter selectively converting said digitized video signals to analog signals according to a predetermined transfer function and providing said standard format video signal on said output;
- and
- said luminance input filter having an equalization response bearing a predetermined relationship to at least one characteristic of said transfer function.
A video system comprising:
- a video input for receiving a video signal;
- a decoder connected to receive said video signal and responsively generating digital component video signals on a decoder output;
- a parser connected to said decoder output for receiving said digital video signals and responsively routing luminance and color difference signals to an input filter;
- said input filter having an equalization response for compensating said luminance signal;
- a format converter having an input connected to said filter for receiving a compensated luminance signal and said color difference signals and an output connected to a digital-to-analog converter, said format converter selectively generates a compensated digital video signal;
- said digital-to-analog converter selectively generates and outputs at least one analog video signal responsive to said compensated digital video signal;
- at least one video device connected to receive said at least one analog video signal.
A method of encoding video signals comprising the steps of:
- receiving a digital video signal;
- separating said digital video signal into a luminance component and a color difference component;
- filtering said luminance component to form a frequency response equalized luminance component;
- generating a digitized component analog video signal using said equalized luminance component.
Dependencies are inferred from the claim text.