A Review of Issues Related to the Choice of Sample Rates for Digital Audio

Author(s): J. J. Gibson
Publisher: Society of Motion Picture and Television Engineers
Publication Date: 1 February 1982
Conference Location: Nashville, TN, USA
Conference Date: 5 February 1982
Page(s): 91 - 104
ISBN (Paper): 978-1-61482-912-6
DOI: 10.5594/M00626



During 1981 significant progress has been made towards the adoption of 48 kHz as a standard sample rate for digital audio to be used in professional audio equipment as well as in television and motion picture systems. This progress is the result of substantial work done by a number of technical committees sponsored by the SMPTE, the Audio Engineering Society (AES), the European Broadcast Union (EBU), the International Radio Consultative Committee (CCIR), and the International Electrotechnical Commission (IEC). This paper reviews the issues which have been debated in these committees and the background for the choice of 48 kHz among several candidates, some of which have been in use for some time. - In the spirit of reaching an agreement on the sample rate, compromises and sacrifices have been made. Of particular concern for the 525/60-color television system is that 8008 audio samples must be distributed, on the average, on 5 frames, i.e. not all frames will contain the same number of samples. It will be shown that this five-frame periodicity will not constrain editing and switching, but that it will require added hardware. The 625/50 television system as well as the 48 frames per second motion picture system will not suffer from this problem, i.e. each frame will contain the same number of samples as the preceding frame. - Finally the paper will discuss the implications of the fact that certain consumer products now in existence or about to be marketed may operate with a different sample rate than 48 kHz.