Method and apparatus for correction of time base errors
AssigneePixelworks, Inc.
InventorNeil Woodall
Life of this patent
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Abstract
The present invention provides a method and apparatus for the correction of time base errors in a video signal. The method and apparatus may combine a horizontal scaler and a time base corrector. A time base corrector in accordance with the present invention can function without locking a clock to a horizontal synchronization signal. Furthermore, a method or apparatus in accordance with the present invention may operate as a finite impulse response filter, an infinite impulse response filter, a low pass filter or an adaptive filter.
Claims29
A circuit comprising:
- a scaler;
- and
- a time base filter connected with the scaler, the time base filter to convert a video signal to a constant number of vertically aligned samples per line, to use a current horizontal synchronization signal to calculate a starting position for a prior line and to operate as an adaptive filter;
- where the time base filter samples a video signal without locking to a horizontal synchronization signal.
A circuit comprising:
- a scaler;
- and
- a time base filter connected with the scaler, the time base filter to convert a video signal to a constant number of vertically aligned samples per line;
- where the time base filter filters line lengths to reduce noise in a video signal;
- where the time base filter filters line lengths as a function of a phase error;
- and
- where the phase error includes a difference between a current line length and a target line length.
A circuit comprising:
- a scaler;
- and
- a time base filter connected with the scaler, the time base filter to convert a video signal to a constant number of vertically aligned samples per line;
- where the time base filter includes a low pass filter to filter a phase error;
- and
- where the phase error includes a difference between a current line length and a target line length.
A method comprising:
- determining a line length for an input signal;
- and
- filtering the input signal responsive to the determination;
- where the filtering the input signal is a function of a phase error;
- and
- where the phase error includes a difference between a current line length and a target line length.
A method of operating a time-base correction circuit comprising:
- determining a line length for an input signal;
- using a current horizontal synchronization signal to calculate a starting position for a prior line;
- sampling the input signal without locking to a horizontal synchronization signal;
- filtering the input signal responsive to the determination;
- and
- scaling the filtered input signal.
A method of operating a time-base correction circuit, comprising:
- determining a line length for an input signal;
- sampling the input signal without locking to a horizontal synchronization signal;
- filtering line lengths to reduce noise in the input signal responsive to the determination by filtering the line lengths as a function of phase error where the phase error includes a difference between a current line length and a target line length;
- and
- scaling the filtered input signal.
A time base correction circuit, comprising:
- a filter to filter image data responsive to a horizontal synchronization signal;
- and
- a scaler to scale the digital image data responsive to the filter;
- where the filter samples the image data without locking to a horizontal synchronization signal.
Dependencies are inferred from the claim text.