Technique for reducing transmission error propagation in an adaptively predicted DPCM video encoder
First Claim
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1. Apparatus for encoding a video signal representing the intensity of picture elements (pels) of a picture including:
- means (105) for predicting the intensity of each pel as a function of reconstructed intensity values of previously encoded pels;
means (107) for forming an error signal indicative of the difference between the intensity of each pel and the predicted intensity thereof;
means (108) for quantizing said error signal; and
means (110) for combining the quantized error signal with said predicted intensity to form said reconstructed intensity value,wherein said predicting means (105) includes;
first means (113) for forming an intermediate prediction of the intensity of said each pel as a function of the reconstructed intensity value of at least a selected one of the pels in the neighborhood thereof; and
second means (114) for forming said predicted intensity as a function of said intermediate prediction,characterized in that said second forming means (114) forms said predicted intensity also as a function of the reconstructed intensity values of at least first and second ones of said neighboring pels.
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Abstract
Propagation of transmission errors in adaptively predicted, DPCM encoded video signals is reduced by including a leak circuit (114) in the encoder (FIG. 1). The leak circuit modifies each prediction in response to local characteristics in the area of the picture being encoded.
27 Citations
8 Claims
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1. Apparatus for encoding a video signal representing the intensity of picture elements (pels) of a picture including:
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means (105) for predicting the intensity of each pel as a function of reconstructed intensity values of previously encoded pels; means (107) for forming an error signal indicative of the difference between the intensity of each pel and the predicted intensity thereof; means (108) for quantizing said error signal; and means (110) for combining the quantized error signal with said predicted intensity to form said reconstructed intensity value, wherein said predicting means (105) includes; first means (113) for forming an intermediate prediction of the intensity of said each pel as a function of the reconstructed intensity value of at least a selected one of the pels in the neighborhood thereof; and second means (114) for forming said predicted intensity as a function of said intermediate prediction, characterized in that said second forming means (114) forms said predicted intensity also as a function of the reconstructed intensity values of at least first and second ones of said neighboring pels. - View Dependent Claims (2, 3, 4)
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5. Apparatus for encoding a video signal comprising a series of samples each representing the intensity of an associated element of a picture, comprising:
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(a) means for predicting the value of each sample based upon the values of prior samples; (b) means for modifying each prediction to reduce the effects of transmission errors on the decoded version of said video signal, and (c) means for transmitting the error signal formed by subtracting each modified prediction from the corresponding one of said samples, wherein said modifying means includes means for attenuating said prediction as a function of (1) the intensity of ones of said picture elements in the vicinity of the element associated with the prediction and (2) the range of possible intensity values for said picture elements. - View Dependent Claims (6, 7)
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7. The invention defined in claim 6 wherein said apparatus also includes:
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(1) means for forming reconstructed versions of each sample using outputs from said transmitting means and said modifying means, and (2) means for storing ones of said reconstructed versions, wherein said predicting means and said modifying means are each responsive to said storing means.
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8. A method of encoding a video signal representing the intensity of picture elements (pels) of a picture including the steps of:
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predicting the intensity of each pel as a function of reconstructed intensity values of previously encoded pels; forming an error signal indicative of the difference between the intensity of each pel and the predicted intensity thereof; quantizing said error signal; and combining the quantized error signal with said predicted intensity to form said reconstructed intensity value, wherein said predicting step includes the steps of; forming an intermediate prediction of the intensity of said each pel as a function of the reconstructed intensity value of at least a selected one of the pels in the neighborhood thereof; and forming said predicted intensity as a function of said intermediate prediction, characterized in that said last mentioned forming step includes forming said predicted intensity also as a function of the reconstructed intensity values of at least first and second ones of said neighboring pels.
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Specification