This new biennial report is intended to support technical specialists and managers in understanding the major digital broadcasting techniques, and the sound and video compression technologies which underlie these techniques.
This Handbook is intended to support technical specialists and managers in understanding the major digital broadcasting techniques, and the sound and video compression technologies which underlie these techniques.
The Handbook begins with an introduction to audio sampling and compression and a detailed description of the internal operation of MP3 (MPEG Audio, Layer III) compression. Other approaches to lossy compression are discussed. We then describe in detail AAC (MPEG-2/4 Advanced Audio Coding), which with HE-AAC (AAC+) is very widely used, for instance in the iTunes system.
We describe MPEG-2 and the increasingly widely used MPEG-4 video compression techniques, which are used in all broadcasting, DVD-based and IP-based digital video delivery systems. We also discuss MPEG-4’s major non-video-related techniques, including animation, Java-based interactivity and synthetic speech.
The main focus of the Handbook is broadcasting - and we provide a review of radio propagation and analogue transmission techniques. The behaviour of radio waves, antennae and modulation schemes gives rise naturally to certain areas of coverage and interference - and therefore to certain business and regulatory models with more or less flexibility and localised programming.
The DVB (and Japanese ISDB) approaches to digital broadcasting use completely different modulation techniques, with far-reaching implications for broadcasters, regulators and listeners/viewers. Far more programs can be delivered in a given radio frequency bandwidth, and it is possible and often desirable to construct large Single Frequency Networks (SFN) covering much larger areas with a single set of programs than is possible with analogue techniques. This leads to transmission systems being a shared resource which is likely to be owned collectively by, or separately from, the broadcasters themselves. This leads to lower costs of entry and to a greater variety of organisations becoming broadcasters.
In contrast, the approaches to digital sound and video broadcasting which are favoured in the USA and some other American countries do not provide much greater capacity per MHz, do not enable the use of Single Frequency Networks or support multiple broadcasters sharing a transmission system. Consequently, these technologies tend to consolidate the positions of organisations who already own spectrum.
We discuss the terrestrial television systems DVB-T and its successor DVB-T2, both of which are based on the OFDM system which facilitates robust, high-efficiency data delivery in a wide variety of conditions. DVB-T2 is optimised for the post Analogue Switch Off environment, when digital stations are able to transmit at higher powers and are free of concerns about interfering with analogue receivers’ low-selectivity tuners. DVB-T2 is capable of delivering several HDTV programs per 8MHz channel, and with still greater efficiency if multiple UHF channels are bonded together using Time-Frequency Slicing. We also discuss the US-based ATSC 8-VSB system, where one 6MHz channel can deliver one or perhaps two HDTV programs.
The Digital Audio Broadcasting (DAB, or DMB for Digital Multimedia Broadcasting) techniques are widely used in many countries. We discuss DAB, the oldest successful digital broadcasting technique and its successor, DAB+, which uses more advanced modulation techniques and more efficient AAC+ compression techniques. We also discuss satellite digital broadcasting systems including DVB-S and DVB-S2.
Terrestrial and/or satellite transmitters can be used for another class of broadcasting, which has something in common with the terrestrial and satellite video broadcasting: mobile broadcasting to handheld and vast-moving vehicular-mounted receivers. We describe DVB-H and its S-band satellite extension DVB-SH. We also discuss Qualcomm’s MediaFLO system, which is increasingly used in North America, and the major Asian Digital Mobile Broadcasting systems such as the satellite-based MobaHo.
This Handbook provides a solid introduction to a rapidly expanding field, in which new technologies compete not just with established technologies, but vie for success in promising new markets such as mobile video broadcasting.
Data in this report is the latest available at the time of preparation and may not be for the current year.