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In article <7813@eddie.MIT.EDU> nathan@eddie.MIT.EDU (Nathan Glasser) writes:
>What exactly is the capacity of a standard size CD, both in bytes and
>in playing time for music (assuming a standard speed)? I've been
>wondering this since I have this feeling that music CD's are quite
>wasteful of space. Some of them may have only about a half an hour's
>worth of music, whereas others have almost an hour. Some have 9 songs
>and some have 25 songs.  Is there a limit to the number of "tracks"
>that they can have? 

If you are seriously interested in these questions, there have been a couple
of excellent, detailed, and *long* postings in rec.audio recently.  Try to
read them if they haven't expired.  I'll summarize briefly:

First the easy part.  A CD, by definition, may have no more than 99 tracks.
This is so a 2-digit decimal display is guaranteed to be sufficient.  Each
track may be subdivided into no more than 99 indices (same reason).  Very
few music CDs actually contain indices, and many CD players don't support them.
A few test disks with 99 tracks (and some tracks with 99 indices) can be had.

The playing time question is more complicated than you might think.  While
there is a theoretical upper bound due to the size of the disk and the
track density, in practice this can not be reached because of distortions
caused by non-flatness in the plastic near the outer edge of the CD.  When
CDs were first released, the practical maximum was around 72 minutes.  Since
then, improvements in manufacturing techniques have increased this to around
75 or 76 minutes.

The usable data is given approximately by:

			2 bytes       44,100 samples   60 sec
	2 channels x -------------- x -------------- x ------ x ~75 min
		     channel-sample       second        min

and if I haven't messed up my arithmetic, that comes out to about 757 MB.
I seem to recall a number more like 550 MB fro a discussion about CD-ROM,
so there may be some added redundancy or some other factor I haven't taken
into account.

-- 
	Howard A. Landman
	{oliveb,hplabs}!intelca!mipos3!cpocd2!howard
	howard%cpocd2.intel.com@RELAY.CS.NET
	One hand clapping sounds a lot like two hands clapping, only quieter.