2006 Digital Media Technology - Digital TV, Mobile TV, IPTV, MPEG

Trends and frequencies

As a prelude to detailed discussion of the various digital broadcasting technologies, we review the propagation of radio waves, the established analogue broadcasting techniques and the resulting spectrum management arrangements in which digital broadcasting takes place. We summarise the key technical and commercial trends and principles we believe characterise the digitisation of broadcasting.

DVB and ISD B

The distinctions between digital broadcasting for stationary video receivers, for mobile receivers and for small handheld devices. DVB standards which are used in most countries for digital video broadcasting. The report also discuss the Japanese ARIB ISDB digital standards, which are similar in principle to DVB-T.

ATSC and Middleware

The North American ATSC digital television broadcasting standard differs greatly from the DVB and ISDB techniques used in other countries. Technologies are looked at which affect broadcast television quality and usage, including real-time vs. offline compression and personal video recorders. The report also discusses the MHEG and MHP middleware and transmission standards for digital television receivers.

Sound and narrowband

Three types of digital broadcasting for sound and data applications are discussed. Firstly, the low data rate systems RDS and DirectBand. Then we explain the capabilities and limitations of Digital Radio Mondaile and the two USA-based In Band On Channel HD Radio systems. Finally we discuss the major wideband audio broadcasting system Eureka 147 and the satellite systems of WorldSpace, Sirius and XM.

Mobile TV

Broadcasting real-time and stored for replay sound, video and multimedia material to small handheld devices such as cellphones is the “Holy Grail” of both the telecommunications and broadcasting industries. We discuss the needs of such systems and the major approaches to achieving it: Eureka 147 T-DMB, DVB-H, ISDB-Tsb and Qualcomm’s promising MediaFlo. We also discuss the Japanese and South Korean MBSAT ‘T-DMB’ broadcast system.

Streaming media and conferencing

The report examines open and proprietary standards including MP3, MPEG-2, MPEG-4, H.264 Advanced Video Coding, Real Networks, Windows Media and Quicktime. Bandwidth restrictions of last-mile technologies such as HFC and ADSL are discussed as well as the advantages and disadvantages of file vs. server streaming for multimedia serving.

Video on demand

The technical principles behind VoD are described, with special reference to IP multicasting, the need for extensive systems integration for all network elements, and the suitability for VoD and ‘triple play’ of the various access technologies: FttH, FttC, HFC, ADSL and WiMAX.

AAC and Video

The report discusses Advanced Audio Coding (AAC) and how it improves on MP3. We explain enhancements to both AAC including Spectral Band Replication (SBR), Parametric Stereo and Scalable Lossless Coding. We discuss HILN parametric audio coding and voice compression algorithms including CELP. We also explain the process of MPEG-2 video compression, which is the basis of almost all digital television systems.

Video and VRML

Advanced Video Coding (AVC/H.264) improves on MPEG-2 video compression. The MPEG-4 standards are of unprecedented scope, including animation, synthetic sound and video, VRML interactivity and Java. We introduce these technologies and discuss how they can be used together to provide services and communication systems far beyond the modes we are familiar with today. We also discuss the MPEG-7 metadata and MPEG-21 digital rights management standards.

MPEG1 and MP3

The report discussed MPEG-1 and MPEG-2 audio compression (coding) and major non-MPEG audio coding systems including Real Audio, Windows Media and Vorbis. A detailed explanation of the internal mechanism of MP3 (MPEG-1 Audio Layer III) compression serves as a basis for understanding MP3pro and all other perceptual audio codecs, including AAC.