Method of flow compression of data transmitted successively between a television transmitter and a television receiver, and a system for carrying out said method
First Claim
1. A method for compression of the flow of data transmitted successively between a television transmitter and a television receiver, the data being representative of the values of luminance or of chrominance of each point of a television image and being coded at the transmitter by means of a differential coding device of the type comprising at least one predictor, a quantizer, a device for reconstruction of the transmitted data and a code allocator, said transmitted data being decoded at the receiver by means of a differential decoder comprising at least one code converter, a predictor and a device for reconstruction of the transmitted data;
- wherein the method comprises the steps of;
determining, prior to transmission, codes to be transmitted as a function of at least two different characteristics Q1 and Q2 of quantization and/or of prediction P1 and P2,transmitting the indication C of a change in characteristic, to the receiver, when coding of the data is obtained by utilizing a characteristic which is different from the characteristic employed for the data previously transmitted, the indication of a change in a characteristic of quantization and/or prediction being transmitted instead of the data relating to the point for which said change takes place, andreconstructing within the receiver the non-transmitted data as a function of the corresponding data of the previous points already received by the receiver wherein the data-coding operation comprises establishing the coding costs and the corresponding codes of the data of each point to be transmitted in respect of each of the characteristics of quantization and/or prediction employed, each cost being obtained by measuring the coding error overshoot in respect of each point, above a visibility threshold at which the error becomes apparent on the received image, in defining a first series C1(i) of costs, for coding the data of each point by utilizing a first characteristic, and a second series C2(i) of costs, for coding the data of each point by utilizing a second characteristic, each cost of one series being obtained from the costs obtained and corresponding to the coding of the preceding point by determining the minumum value of the costs computed as a function either of the preceding cost of the same series or of the preceding cost of the other series;
in determining in each series, by means of a changeover code C, each minimum cost which is obtained from the coding cost of the preceding point of the other series; and
in storing the codes to be transmitted and corresponding to the computed costs of either one series or the other by determining a coding path which alternates on either one series or the other, beginning with those codes of the series in which the last computed cost is lower than the corresponding cost of the other series and continuing successively with the codes of the other series as soon as a changeover code in a series is encountered.
1 Assignment
0 Petitions
Accused Products
Abstract
The method and the system for compression of the flow of data between a television transmitter and a television receiver make provision at the transmitter for a differential coding system comprising a circuit for computation and propagation of coding costs with respect to visibility thresholds at which a coding error becomes apparent on the received image, coding being performed by utilizing at least two different quantization and/or prediction characteristics. A device connected to the differential coding system transmits to the receiver an indication relating to a change in characteristic instead of the data corresponding to the image point to be transmitted when the point is located within an image zone in which the change is necessary. A device is provided at the receiver for reconstructing the data corresponding to the non-transmitted point as a function of data of points already known to the receiver.
64 Citations
11 Claims
-
1. A method for compression of the flow of data transmitted successively between a television transmitter and a television receiver, the data being representative of the values of luminance or of chrominance of each point of a television image and being coded at the transmitter by means of a differential coding device of the type comprising at least one predictor, a quantizer, a device for reconstruction of the transmitted data and a code allocator, said transmitted data being decoded at the receiver by means of a differential decoder comprising at least one code converter, a predictor and a device for reconstruction of the transmitted data;
- wherein the method comprises the steps of;
determining, prior to transmission, codes to be transmitted as a function of at least two different characteristics Q1 and Q2 of quantization and/or of prediction P1 and P2, transmitting the indication C of a change in characteristic, to the receiver, when coding of the data is obtained by utilizing a characteristic which is different from the characteristic employed for the data previously transmitted, the indication of a change in a characteristic of quantization and/or prediction being transmitted instead of the data relating to the point for which said change takes place, and reconstructing within the receiver the non-transmitted data as a function of the corresponding data of the previous points already received by the receiver wherein the data-coding operation comprises establishing the coding costs and the corresponding codes of the data of each point to be transmitted in respect of each of the characteristics of quantization and/or prediction employed, each cost being obtained by measuring the coding error overshoot in respect of each point, above a visibility threshold at which the error becomes apparent on the received image, in defining a first series C1(i) of costs, for coding the data of each point by utilizing a first characteristic, and a second series C2(i) of costs, for coding the data of each point by utilizing a second characteristic, each cost of one series being obtained from the costs obtained and corresponding to the coding of the preceding point by determining the minumum value of the costs computed as a function either of the preceding cost of the same series or of the preceding cost of the other series;
in determining in each series, by means of a changeover code C, each minimum cost which is obtained from the coding cost of the preceding point of the other series; and
in storing the codes to be transmitted and corresponding to the computed costs of either one series or the other by determining a coding path which alternates on either one series or the other, beginning with those codes of the series in which the last computed cost is lower than the corresponding cost of the other series and continuing successively with the codes of the other series as soon as a changeover code in a series is encountered.
- wherein the method comprises the steps of;
-
2. A system for compression of the flow of data transmitted in a television transmitter and television receiver comprising:
-
means for representing the values of luminance and chrominance of each point of a television image contained within said television transmitter by way of differential coding; means for establishing coding costs and the corresponding codes of the data of each point to be transmitted as a function of at least two different characteristics Q1 and Q2 of quantization and/or prediction P1 and P2, each cost being calculated by means for calculating the coding error overshoot with respect to each point, above which a visibility threshold the error becomes apparent on said received images; where said calculating means including; first calculating means for calculating a first series of costs C1(i) of costs and for coding the data of each point utilizing a first characteristic; second calculating means for calculating a second series C2(i) of costs and for coding the data utilizing a second characteristic; means contained in each of said first and second calculating means to calculate the cost of each of the respective series by obtaining said cost obtained and corresponding to the coding of the preceding point by determining the minimum value of the costs computed as a function of the preceding cost in both series and for selecting the minimum cost series; first determining means coupled to said first and second calculating means for producing a changeover code C and for obtaining the coding cost of the preceding point of the non-selected series; storing means for the codes to be transmitted; second determining means coupled to said first determining means for determining a coding path which alternates on either of the two series in accordance with the minimum cost series selected by said first and second calculating means and for continuing with said coding upon receipt of a changeover code C; means for performing the differential coding in said transmitter comprising; at least one predictor; a quantizer; a device for reconstruction of said transmitted data; and a code allocater; means for transmitting the changeover code C; differential decoding means contained within said receiver for decoding said received data comprising; at least one code converter; a predictor; a device for reconstruction of said transmitted data; and C code receiving means coupled to said decoder means for upon receipt of a C code switching to the appropriate code converter. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification