mart@utcsri.UUCP (Mart Molle) (02/26/85)
For a long time in this newsgroup there have been flaming debates about the adequacy of the sampling rate for compact disc recordings. As far as I can remember, these debates have only considered how good (or bad) this sampling rate is for audio reproduction. In the latest issue of _IEEE_Communications_Magazine_ (Vol 23, No. 2, February 1985), there is a tutorial article written by J.B.H. Peek from Philips Research Labs, where the system was first developed, which explains how the digital recording process works. The following paragraph quoted from the article gives a surprising explanation for the selection of 44.1kHz... "Recording: A video recorder is often used in combination with a PCM interface unit for digital recording of the audio signals on magnetic tape. It is because this video recorder uses the PAL television standard that the sampling frequency has been set at 625-37 44.1kHz, which is ------ * 3 * 15625 = 44.1kHz, where 625 625 is the number of lines in a PAL picture, 37 is the number of unused lines, 3 the number of audio samples recorded per line, and 15625 Hz is the line frequency [5]." Reference [5] is: T. Doi, Y. Tsuchiga, and A. Iga, "On several standards for converting PCM signals into video signals," J. Audio Eng. Soc., vol. 26, no. 9, pp. 641-649, Sept. 1978. ------------- Mart L. Molle Computer Systems Research Institute University of Toronto {decvax,ihnp4,decwrl,uw-beaver}!utcsri!mart