Video bandwidth reduction system using a two-dimensional transformation, and an adaptive filter with error correction
First Claim
1. A system for reducing the bandwidth required for the transmission of two-dimensional video data comprising:
- two-dimensional transformer means for transforming said video data into arrays of transform coefficients,transform coefficient compressor means for separating the transform coefficients into zonal coefficients, all of which are transmitted, and non-zonal coefficients of which the largest "n" coefficients are selected for transmission, for arranging the zonal coefficients such that such zonal coefficients may be identified by their position in the stream of data, and for attaching identification data to the non-zonal coefficients; and
transmitting modem means for transmitting the coefficients output from the transform coefficient compressor.
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Accused Products
Abstract
A reduction in bandwidth of two-dimensional video data is obtained by the two-dimensional transformation of the video data by means of one of a class of fast transformations followed by the elimination of certain non-significant transform coefficients prior to the transmission of the transform data. The lower-order transform coefficients or "zonal coefficients" which are usually significant in size, are always transmitted. Prior to transmission, parity bits are added to the zonal coefficients to allow error detection. An adaptive filter eliminates from the higher-order transform coefficients, those non-significant transform coefficients of magnitude less than a threshold level, which level is adjusted in response to the amount of data in the buffer memory awaiting transmission so as to transmit the most significant transform coefficients from a succession of two-dimensional data vectors. At the receiving end of the communication link the array of transform coefficients is reconstituted from the received data. The non-zonal coefficients, eliminated prior to transmission, are replaced by zeros in the reconstituted array. Transmission errors occurring in the zonal coefficients, are detected by parity checks and the erroneous zonal coefficients are replaced by the like transform coefficients from the previously received zonal coefficients corresponding to the prior scan of the same portion of the two-dimensional video data. An approximation to the original video data is obtained by the application of the inverse two-dimensional transformation to the reconstituted array of transform coefficients.
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Citations
7 Claims
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1. A system for reducing the bandwidth required for the transmission of two-dimensional video data comprising:
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two-dimensional transformer means for transforming said video data into arrays of transform coefficients, transform coefficient compressor means for separating the transform coefficients into zonal coefficients, all of which are transmitted, and non-zonal coefficients of which the largest "n" coefficients are selected for transmission, for arranging the zonal coefficients such that such zonal coefficients may be identified by their position in the stream of data, and for attaching identification data to the non-zonal coefficients; and transmitting modem means for transmitting the coefficients output from the transform coefficient compressor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification