Rai Radiotelevisione Italiana

Telletra Telefonia Electronica

Rai Radiotelevisions Italiano, S.p.a.

Alcatel Telettra

Mario Stroppiana

Luigi Ronchetti

Marzio Barbero

Mario Muratori

A system for controlling the rate of flow of data generated by a variable rate data source and fed to a buffer which outputs the data at a constant bit rate. The operating mode, which sets the bit rate of the variable rate data source, is determined not only by the degree to which the buffer is filled, but also by the immediately preceding operating mode. The feedback of the operating mode results in an hysteresis effect on the mode, thus reducing the number of changes of the rate of data generation and thereby increasing the transmission quality of the data generated and output from the system.

System for controlling a variable source by the feedback of the running

A method for reducing the information transmitted in the variable length encoding of numerical data blocks with encoding of single values and string lengths of a consecutive value ('run lengths'). Advantageously, the system eliminates that transmission of the last element in a string of recurrent values preceded by a 'run length' and followed by another 'run length' or by a data block end. When the string of recurrent values has a length of only one element, the single element is not transmitted.

System for reducing the information transmitted in the variable length

A converter processes a digital video signal according to a known redundancy reducing algorithm executed on successive block for each frame or field and generates a transformed signal which is applied to a quantizer adapted to generate a quantized signal at preset transition levels on opposed sides of the zero, including the zero ( . . . ,-3,-2,-1, 0, 1, 2, 3, . . . ). The quantized signal is processed by a processor, adapted to determine the block length and the consecutive zero sequences along a preset scanning order, and to output a symbolic signal constituted by symbols indicating the quantization levels of the non-null data, the zero sequences and a symbol indicating the block end. The symbolic signal is applied to a variable length VLC encoder, adapted to encode data according to a preset designation law for generating a signal which is applied to a transmission buffer. The quantized signal generated by the quantizer further includes two ambiguous levels (x1 and x-1) at input values falling within respective preset intermediate ranges respectively between the zero level and the first positive level and between the zero level and the first negative level; the processor transforms each of the ambiguous levels respectively into a first positive level and a first negative level if the preceding and subsequent input values are both non-null and non-ambiguous, and transforms the ambiguous level into zero in all other cases.

Device for reducing the redundancy in blocks of digital video data in

A redundancy reduction algorithm, such as hybrid DCT, is applied to a video signal and is subsequently encoded by pixel blocks, and motion vectors are generated for each image block. At least one global motion vector is then generated for the entire image, the block motion vectors are substracted from the global vector to obtain local motion vectors representing the shifts from the global vector, the global vector is encoded with fixed length, the local vectors are encoded with variable length, and the coded global vector and the coded local vectors are multiplexed into the coded video signal to be transmitted.

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Turin, Italy

Mario Stroppiana