Silvio Cucchi

A bit-rate reduction system for HDTV transmission

The transmission of HDTV (high-definition television) signals on available digital networks and satellites requires the adoption of sophisticated compression techniques to limit the bit-rate requirements and to provide a high-quality and reliable service. A hybrid predictive/transform system has been devised and implemented. The main parameters of this system are in accordance with those being recommended by CMTT for the transmission of conventional component TV. The basic algorithms, the codec architecture, the developed VLSI, and the equipment are described. The codec is designed to operate with the currently envisaged TV and HDTV formats and with a wide range of transmission rates. The optimization of the system and the evaluation of its performance have been carried out on the basis of a large number of subjective tests in accordance with the user requirements specified by the standardization bodies. The codecs have been extensively tested on-field during experimental point-to-multipoint satellite transmission of HDTV signals. >

A novel architecture for VLSI implementation of the 2-D DCT/IDCT

The implementation of a 8*8 two-dimensional forward/inverse discrete cosine transform (DCT) chip is presented. The structure is highly regular and modular and the DCT computation is carried out using registers and adders only. A fully pipelined structure based on a new approach for serial arithmetic computation allows a high throughput capability (i.e., up to 40 MHz). The chip is fully functional and is being employed in the Alcatel Telettra HDTV (high definition television) codec. Fabricated in 1 eta m double-metal CMOS technology by LSI Logic, the chip uses approximately 57000 transistors which occupy a 218-pad die area of 8.6 mm*8.6 mm (56 pads are used).<<ETX>>

Buffer control technique for transmission frequency recovery of CBR connections over ATM networks

The transmission of audio-video coded signals in real time applications over ATM networks requires sophisticated techniques for synchronization and buffer control. The presence of ATM cell delay variation (CDV) represents the major jitter source affecting the reconstruction of the time reference signal associated to the actual real-time service. In this paper is presented a buffer control technique and the related implementation aspects, based on both measure and utilization of CDV statistics or alternatively making use of buffer occupation statistics. The system allows setting target jitter attenuation in a way to have pre-established buffer underflow and overflow probabilities and its optimal utilization. The presented technique can be further extended to any asynchronous network context and is particularly suitable for high demanding professional audio-video applications.

On improving performance of analysis by synthesis speech coders

An algorithm for improving the performance of analysis-by-synthesis (A-by-S) speech coders is presented. It is shown that proper modifications of the A-by-S strategies commonly used to determine the excitation parameters can be devised. In particular, a redefinition of the classical objective function based on the weighted mean squared error criterion may allow a better tracking of the speech signal transients as well as a better alignment of the synthetic pitch pulses. The implementation details of the algorithm are discussed and experimental results are presented.

Performance of an HDTV codec adopting transform and motion compensation techniques

Digital techniques are widely adopted to process the video signal, and nowadays there is the necessity of transmitting conventional and high-definition television signals between different studios. In the near future it could be possible to deliver a digital signal to the consumer. To allow the use of the presently available digital networks and satellites, sophisticated compression techniques have been devised to limit the bit-rate requirements and to provide a high-quality and reliable service. A hybrid predictive/transform system has been devised and implemented in the framework of the European project EU 256. The main parameters of this system are in accordance with those being recommended by ETSI and CMTT for the transmission of conventional component TV. Codecs are available for the TV and HDTV formats presently in use and can operate with a wide range of transmission rates. The optimization of the system and the evaluation of its performance have been carried out on the basis of a large number of subjective tests in accordance with the user requirements specified by the standardization bodies. The codecs have been extensively tested on-field during experimental point-to-multipoint satellite transmission of HDTV signals on the occasion of soccer matches.