INTRODUCTION

Television is one of the most widely available means of communication. Large screen, high-definition television is the target for the next step in television, and may bring about a new standard system which will be common throughout the world. It will perform the same function better and will also provide a powerful tool for other uses. These will include film production for the cinema and for television, printing, medical applications and scientific work.

The move to HDTV production offers new opportunities to simplify programme exchange and to bring together the production of programmes for television and for the cinema. A single standard would be beneficial to producers, as well as broadcasting organizations.

Figure 1, which is based on a suggestion by Prof. Krivocheev, is a simplified schematic of the expected future environment for HDTV, as it relates to broadcasting. The central element is the HDTV production centre, whose activities in programme production and programme exchange will be similar to those of today's production centre. While most of these activities will be in high definition, provision must be made to work with a number of other contribution formats, such as current 525- or 625-line television in analogue or digital forms, film, etc. The introduction of high-definition television offers a new opportunity to simplify the exchanges of both recorded and live programme material.

A feature of HDTV production is the capability to produce films suitable for projection in the cinema. Thus a high-quality video-to-film transfer process will be particularly important for the production centre.

HDTV signals from the production centre will pass to the delivery network at the broadcast distribution interface. Delivery to the viewer may use one of a number of possible methods including terrestrial broadcasting (e.g., VHF or UHF), satellites, cables (e.g., coaxial or fibre - optical fibres are considered to be one of the most promising transmission media for wideband HDTV) or pre-recorded media (e.g., cassettes or disks). Each has particular characteristics and, as a consequence, the HDTV signal must be converted into a form appropriate for each delivery method. This will be accomplished in an encoder or converter between the HDTV signal at the broadcast interface and the delivery interface.