[net.audio] Why CD Sampling Rate = 44.1kHz

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