Hearing and seeing are just two of our senses and we take them for granted, that is until we lose – or notice an impairment in – one or both of them.

In this Article, brief mention is made of the physiology of the eye and the ear, and how the combination of this complex eye/ear/brain relationship can assist engineers in the design of compressed data equipment. Comments are then made to show that perhaps care should be taken not to push the exploitation of the so-called deficiencies of our seeing and hearing organs too far. Finally some comments are given on more work that needs to be done to try to determine just how much "cheating" can be tolerated by we humans before the results become unacceptable.

The EC project, RACE MOSAIC, was set up to find ways of overcoming specific digital picture quality issues (e.g. content-dependent encoding performance, codec cascading and dynamic statistical multiplexing). In the framework of this project, a new methodology has been designed to allow subjective assessment of both picture and service quality, in conditions that are closer to the actual home environment.

This Article describes the new method – known as Single-Stimulus Continuous Quality Evaluation and, more particularly, "SSCQE Stage 1" which was recently introduced in ITU-R Recommendation BT.500-7.

The double-stimulus DSCQE methodology – recently studied in the EC project, ACTS TAPESTRIES – is an adaptation of SSCQE. DSCQE has been proposed to the MPEG-4 group to address the specific issue of error-robustness evaluation, and is briefly described here.

Which role does picture quality play in the new competitive world of multi-channel digital television services? In order to suggest an answer to this and other questions, RAI Research centre – in collaboration with TDF-C2R – is committed to studies which relate to the quality evaluation of compressed digital video sequences.

This Article collects together the preliminary results obtained within the framework of the ACTS Project, QUOVADIS, and briefly describes the future planned studies to be carried out within the ACTS Project, TAPESTRIES.

In this article the Author considers, firstly, a hypothetical broadcast network in which compression equipments have replaced several existing functions – resulting in multiple-cascading. Secondly, he describes a similar network that has been optimized for compression technology.

Picture-quality assessment methods – both conventional and new, subjective and objective – are discussed with the aim of providing background information. Some proposals are put forward for objective evaluation together with initial observations when concatenating (cascading) codecs of similar and different types.

The European Space Agency (ESA) has investigated the use of multiregional highly-inclined eliptical orbit (M-HEO) satellites for digital radio systems. these studies have demonstrated, in particular, that it is possible to use the Eureka-147 DAB system – delivered by six HEO satellites – to provide a digital radio service to Europe, North America and East Asia.

This article describes how these studies, sponsored by ESA and carried out by DLR and IRT, set out to answer unresolved questions about the transmission channel and the use of the Eureka-147 system under operational conditions.