Error concealment in digital television signals
First Claim
1. A method of concealing errors in a composite PAL or NTSC digital television signal, which television signal comprises a plurality of sample signals corresponding respectively to sample positions along a horizontal scan line of a television picture made up of a plurality of said horizontal lines, the method comprising, in respect of each said sample signal:
- using a first algorithm to calculate a first expected value of said sample signal, said first algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal for said calculation;
performing a first comparison between said first expected value and the actual value of said sample signal;
using a second algorithm to calculate a second expected value of said sample signal, said second algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal and actual values of adjacent sample signals in the horizontal lines preceding and following the horizontal line of said sample signal;
performing a second comparison between said second expected value and the actual value of said sample signal;
continuously storing an indication as to which of said first and second comparisons gives a result closer to zero; and
on occurrence of an error sample signal substituting a corrected sample signal for said error sample signal so as to conceal the error, said corrected sample signal being generated using said first or second algorithm in dependence on said indication.
1 Assignment
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Accused Products
Abstract
A method of concealing errors in a composite PAL or NTSC digital television signal formed of sample signals corresponding respectively to sample positions along horizontal scan lines of a television picture made up of a plurality of such horizontal lines, comprises, in respect of each sample signal the steps of, using a first algorithm to calculate a first expected value of the sample signal, the first algorithm using actual values of adjacent sample signals in the same horizontal line as the sample signal, using a second algorithm to calculate a second expected value of the sample signal, the second algorithm using actual values of adjacent sample signals in the same horizontal line as the sample signal and actual values of adjacent sample signals in the horizontal lines preceding and following the horizontal line of the sample signal, continuously monitoring which of the first and second algorithms gives expected values closer to the actual values, and on occurrence of an error sample signal using the algorithm currently giving the better result to calculate a corrected sample signal to be substituted for the error sample signal.
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Citations
7 Claims
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1. A method of concealing errors in a composite PAL or NTSC digital television signal, which television signal comprises a plurality of sample signals corresponding respectively to sample positions along a horizontal scan line of a television picture made up of a plurality of said horizontal lines, the method comprising, in respect of each said sample signal:
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using a first algorithm to calculate a first expected value of said sample signal, said first algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal for said calculation; performing a first comparison between said first expected value and the actual value of said sample signal; using a second algorithm to calculate a second expected value of said sample signal, said second algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal and actual values of adjacent sample signals in the horizontal lines preceding and following the horizontal line of said sample signal; performing a second comparison between said second expected value and the actual value of said sample signal; continuously storing an indication as to which of said first and second comparisons gives a result closer to zero; and on occurrence of an error sample signal substituting a corrected sample signal for said error sample signal so as to conceal the error, said corrected sample signal being generated using said first or second algorithm in dependence on said indication. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for concealing errors in a composite PAL or NTSC digital television signal, which television signal comprises a plurality of sample signals corresponding respectively to sample positions along a horizontal scan line of a television picture made up of a plurality of said horizontal lines, the apparatus comprising:
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means operative in respect of each said sample signal to use a first algorithm to calculate a first expected value of said sample signal, said first algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal for said calculation; means for performing a first comparison between said first expected value and the actual value of said sample signal; means operative in respect of each said sample value to use a second algorithm to calculate a second expected value of said sample signal, said second algorithm using actual values of adjacent sample signals in the same horizontal line as said sample signal and actual values of adjacent sample signals in the horizontal lines preceding and following the horizontal line of said sample signal; means for performing a second comparison between said second expected value and the actual value of said sample signal; means for continuously storing an indication as to which of said first and second comparisons gives a result closer to zero; and means operative on occurrence of an error sample signal to substitute said corrected sample signal for said error sample signal so as to conceal the error, said said corrected sample signal being generated using said first or second algorithm in dependence on said indication.
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Specification