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ISO/MPEG layer III audio coding: CD-like quality with only 9 per cent of the data rate

: Grill, B.; Popp, H.

National Association of Broadcasters -NAB-:
NAB HDTV World Conference 1993. Proceedings
Washington, DC: NAB Services, 1993
ISBN: 0-89324-163-6
HDTV World Conference <3, 1993, Las Vegas/Nev.>
Fraunhofer IIS A ( IIS) ()
audio coding; data compression; Datenkompression; Datenreduktion; error concealment; Fehlerverschlüsselung; gehörangepaßte Codierung; Layer-3; low bitrate audio coding; MPEG-Standard; NMR; Noise to mask ratio; perceptual coding; psychoacoustic; Psychoakustik; Toncodierung

The ISO-MPEG-Layer III digital audio compression alogrithm is the most powerful of the three audio compression schemes standardized in ISO/MPEG IS-11172 in November 1992. Layer III, which merges the best parts from the ASPEC and MUSICAM algorithms can be used for encoding audio data at medium to very high compression rates from a factor of 3 to 12 while maintaining CD-like quality. Higher compression rates can be achieved at the expense of the audio bandwidth. Tests performed by independent institutions on behalf of ISO and CCIR have shown the excellent performance of Layer III at bit rates which are low enough to permit real-time transmission on the ISDN network. With the ISDN currently being installed world-wide as a successor for today's telephone net, Layer III opens up new possibilities for connections with CD-like audio quality via a standard dial up network. This paper introduces some basic principles of psychoacoustic (perceptual) sound coding. The Layer III algorithm will be e xplained togehter with implementation aspects. Furthermore results of the tests performed by CCIR and ISO are presented. Finally some practical applications are given.