Cselt-Centro Studi E Laboratori Telecomunicazioni S.p.a.

S.i.p. Societa' Italiana Per L'esercizio Telefonico P.a.

Mario Guglielmo

Benedetto Riolfo

Giovanni Baronetti

Leonardo Chiariglione

Fabrizio Oliveri

Luigi Corgnier

Garibaldi Conte

The method of and the device for digital signal coding by vector quantization exploit representation of signal portions in a one-dimensional space for vector codebook generation and for coding for transmission and/or storage purposes. The n-dimensional sampling is transformed into coordinates in one-dimensional space preferably in accordance with Hilbert's curve.

Method of and system for digital signal coding by vector quantization

Coder-decoder of television pictures for transmission and/or reception via digital low-speed channel. In transmission, it first carries out the bidimensional transform of digital sample blocks of the television signal and then a dichotomic quantization thus obtaining quantized coefficients with variable length as a function of the coefficient index; in reception, it first carries out a quantization for quantized coefficients re-assignment of suitable quantization levels, and then the bidimensional antitransform for obtaining again the digital television signal samples. An optimized configuration of digital sample memory in transmission and in reception is shown in FIG. 1.

Coder-decoder for transmission and/or reception of television pictures

A train of incoming data words, specifically digitized video samples arrayed in frames of Y lines of X pixels each which have already undergone a 2-dimensional spatial transformation, is scrambled by being divided into Z sequences (frames) whose data words are temporarily written in respective cells of Z.sup.2 storage units of a memory of dynamic-RAM Type. The Z.sup.2 storage units, each divided into Z sections, are read out in cyclic-succession--at a rate of one cell per unit--and each cell is reloaded immediately after being vacated. Reading and writing occurs for one set of Z sequences in a first addressing mode, conforming to the order of arrival of the data words in the incoming train, and for the next set in a second addressing mode involving the grouping of homologous data words of respective sequences into successive series of Z data words each. The two addressing modes alternate for consecutive sets and the outgoing train so formed can be subjected to a further transformation before being transmitted to a remote station for unscrambling.

System for spatially and temporally transposing data words arrayed in

A two-dimensional data array, such as an orthogonally scanned television image, is divided into a multiplicity of elemental blocks each containing a given number of PCM samples which are converted by linear transformation into a series of coefficients to be quantized for transmission to a remote receiver. The data blocks are processed one at a time by an iterative coder which allots a progressively increasing number of bits to a given block in successive operating stages, the bits being allocated to the several coefficients of the block according to the position of the barycenter of their signal energy assigning the block to one of K classes. An initial overall reconstruction error, computed from the coefficients of a block with no bits yet available for quantization, is updated with each bit allotment in the course of an iteration in which a selected coefficient is subjected to simultaneous coding with S quantizers differing from one another in their quantum steps. The coding operations of the S concurrently active quantizers have different error-reducing effects and the resulting minimum error is compared with a threshold which itself may be variable according to the activity of the image block being processed. When the residual overall error falls below that threshold, processing is terminated and the bits used in the coding of each coefficient are sequentially sent out together with a count of the total number of bits allotted to the block and a parameter k indicating its classification, this information enabling the receiver to reconstruct the image within the limits of the tolerated residual error.

Growing community of inventors

Montalenghe, Italy

Mario Guglielmo