While many digital TV production systems have been introduced in isolated “islands”, there is increasing user demand to incorporate these islands into larger networked infrastructures. As a consequence, television production is currently undergoing a second phase of digitalization – the move towards IT-based technologies.

By way of an introduction to the AAF, GXF and MXF articles published in this issue of EBU Technical Review, this article presents – in a broader context – the file formats and systems issues that are likely to be encountered when migrating to “file-oriented” TV production.

The Advanced Authoring Format (AAF) enables content creators to easily exchange digital media – essence – and metadata across platforms, and between applications. It simplifies project management, saves time and preserves valuable metadata that was often lost in the past when transferring essence between applications.

The Material eXchange Format is an open file format, aimed at the interchange of AV material along with associated data and metadata. It establishes interoperability of content between various applications used in the television production chain. This leads to operational efficiency and creative freedom through a unified networked environment.

The General eXchange Format was originally conceived by Grass Valley Group for the interchange of simple camera shots over data networks, and for archival storage on data tape. Over the years it has evolved to include additional compression types, and support for compositions with video cuts, audio fades and metadata. It is now an SMPTE standard.

CT-aacPlus is a combination of Spectral Band Replication (SBR) technology – a bandwidth-extension tool developed by Coding Technologies (CT) in Germany – with the MPEG Advanced Audio Coding (AAC) technology which, to date, has been one of the most efficient traditional perceptual audio-coding schemes.

CT-aacPlus is able to deliver high-quality audio signals at bit-rates down to 24 kbit/s for mono and 48 kbit/s for stereo signals. The forthcoming Digital Radio Mondiale (DRM) broadcasting system, among others, will use CT-aacPlus for its audio-coding scheme. CT-aacPlus will enable DRM to deliver an audio quality, in the frequency range below 30 MHz, that is equivalent to – or even better than – that offered by today’s analogue FM services.

This article describes the principles of traditional audio coders – and their limitations when used for low bit-rate applications. The second part describes the basic idea of SBR technology and demonstrates the improvements achieved through the combination of SBR technology with traditional audio coders such as AAC and MP3.

The EBU recently carried out a survey of its Members to establish the extent of their Internet and webcasting activities. The results are reported here and offer a valuable snapshot of the webcasting activities of EBU Members in late 2001.

Danmarks Radio (DR) has carried out an analysis on how to establish an MHP application development environment.

In this article, some of the conclusions and considerations are presented. Different areas of relevance are discussed: the technical changes in the transmission chain, the establishment of the application development environment and some aspects of the play-out system.