Television digital signal processing apparatus employing time-base correction
AssigneeYves C. Faroudia
InventorSteven D. Wagner
Life of this patent
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Abstract
A color television signal, digitized by a sampling clock asynchronous with respect to the television signal's horizontal synchronizing pulses, is applied to a dynamically programmable digital filter which upsamples or downsamples the received digitized television signal over short time periods in response to time-base disturbances in the signal. The user may also select a higher or lower long-term clock frequency. Resampled digital samples are applied to a FIFO memory for readout at a clock rate which follows the time-averaged horizontal frequency of the received digitized television signal, or, alternatively, at a substantially fixed clock rate, asynchronous with respect to the horizontal line frequency of the received digitized color television signal.
Claims19
A time-base corrector receiving a digitized color television signal made up of digital samples representing an analog television signal digitized by a sampling clock asynchronous with respect to the analog television signal's horizontal synchronizing pulses, whereby the number of digital samples in response to each horizontal line of the analog television signal may vary and the relative time alignment of the first digital sample of each horizontal line may vary with respect to the horizontal synchronizing pulse of the corresponding analog television signal's horizontal line, comprising
- means for resampling said digitized color television signal to produce resampled digital samples, said means for resampling having a controllable sampling-rate-conversion ratio;
- means for controlling the sampling-rate-conversion ratio of said means for resampling, said means for controlling including a feedback loop having an input and an output, said feedback loop receiving said resampled digital samples at its input and providing a sampling-rate-conversion ratio control at its output;
- means for storing said resampled digital samples;
- means for reading out stored resampled digital samples;
- and
- wherein each of said first three recited means operates exclusively in the digital domain.
A television signal processing and reproduction system, comprising means for digitizing an analog color television signal, said means including analog-to-digital conversion means employing a sampling clock asynchronous with respect to the analog television signal's horizontal line frequency, whereby the number of digital samples in response to each horizontal line of the analog television signal may vary and the relative time alignment of the first digital sample of each horizontal line may vary with respect to the horizontal synchronizing pulse of the corresponding analog television signal's horizontal line;
- time-base corrector means, including
- means for resampling said digitized color television signal to produce resampled digital samples, said means having a controllable sampling-rate-conversion ratio;
- means for controlling the sampling-rate-conversion ratio of said means for resampling, said means including a feedback loop having an input and an output, said feedback loop receiving said resampled digital samples at its input and providing a sampling-rate-conversion ratio control at its output;
- means for storing said resampled digital samples,
- means for reading out stored resampled digital samples;
- wherein each of said first three recited means operates exclusively in the digital domain;
- monitor-type reproducer means, said reproducer means requiring an analog video input that has been time-base stabilized to a highly stable clock locked to the television signal's horizontal line frequency;
- and
- means, includes digital-to-analog converter means, for coupling said time-base corrector means to said monitor-type reproducer means.
A television signal processing and reproduction system, comprising means for digitizing an analog color television signal, said means including analog-to-digital conversion means employing a sampling clock asynchronous with respect to the analog television signal's horizontal line frequency, whereby the number of digital samples in response to each horizontal line of the analog television signal may vary and the relative time alignment of the first digital sample of each horizontal line may vary with respect to the horizontal synchronizing pulse of the corresponding analog television signal's horizontal line;
- time-base corrector means, including
- means for resampling said digitized color television signal to produce resampled digital samples, said means having a controllable sampling-rate-conversion ratio;
- means for controlling the sampling-rate-conversion ratio of said means for resampling, said means including a feedback loop having an input and an output, said feedback loop receiving said resample digital samples at its input and providing a sampling-rate-conversion ratio control at its output;
- means for storing said resampled digital samples;
- means for reading out stored resampled digital samples;
- wherein each of said first three recited means operates exclusively in the digital domain;
- line doubler means receiving said read-out stored resampled digital samples, said line doubler means including digital-to-analog converter means;
- and
- monitor-type reproducer means receiving the output of said line doubler means, said reproducer means requiring an analog video input that has been time-base stabilized to a highly stable clock locked to the television signal's horizontal line frequency.
A television signal processing and reproduction system, comprising means for digitizing an analog color television signal, said means including analog-to-digital conversion means employing a sampling clock asynchronous with respect to the analog television signal's horizontal line frequency, whereby the number of digital samples in response to each horizontal line of the analog television signal may vary and the relative time alignment of the first digital sample of each horizontal line may vary with respect to the horizontal synchronizing pulse of the corresponding analog television signal's horizontal line;
- time-base corrector means, including
- means for resampling said digitized color television signal to produce resampled digital samples, said means having a controllable sampling-rate-conversion ratio;
- means for controlling the sampling-rate-conversion ratio of said means for resampling, said means including a feedback loop having an input and an output, said feedback loop receiving said resampled digital samples at its input and providing a sampling-rate-conversion ratio control at its output;
- means for storing said resampled digital samples,
- means for reading out stored resampled digital samples;
- wherein each of said first three recited means operates exclusively in the digital domain;
- and
- digital bit-rate reducer means receiving said read-out stored resampled digital samples, said bit-rate reducer means requiring a video input that has been time-base stabilized to a highly stable clock locked to the television signal's horizontal line frequency.
Dependencies are inferred from the claim text.