nathan@eddie.MIT.EDU (Nathan Glasser) (01/07/88)
This isn't really about anything interactive, but since there's been
some discussion of CD roms here, this isn't such an inappropriate question.
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?
Thanks,
--
Nathan Glasser
fnord nathan@{mit-eddie.uucp, xx.lcs.mit.edu}
"A tribble is the only love that money can buy."
Presently there is insufficient evidence to conclude that tribbles spread AIDS.olson@endor.harvard.edu (Eric K. Olson) (01/08/88)
In a recent article Nathan Glasser writes: >and some have 25 songs. Is there a limit to the number of "tracks" >that they can have? Our CD player at home only has 32 track display indicators. I wonder if that's a standard, or our player is crippled for CDs with >32 tracks. -Eric (defun maybe (x) (maybe (not x))) Eric K. Olson olson@endor.harvard.edu harvard!endor!olson D0760 (Name) (ArpaNet) (UseNet) (AppleLink)
hull@hpsal2.HP.COM (James Hull) (01/08/88)
> What exactly is the capacity of a standard size CD, both in bytes and > in playing time for music (assuming a standard speed)? > Nathan Glasser A CD can hold approximately 75 minutes of music (on one side). HP has a CD-ROM product which claims to hold "over 550 megabytes" on a "three-mile long spiral track with a density of 16,000 tracks per inch". The pictures in the brochure definitely show labeling on one side of the disc, so I assume that only one side is being used for data. -- Jim Hull hplabs!hpda!hull
daford@watdragon.waterloo.edu (Daniel Ford) (01/08/88)
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 The capacity of an audio CD is approximatley 60 minutes. The figure of 75 minutes is part of the Sony-Philips standard but most do not use this amount. The capacity in bytes depends on the level of error checking required. Excellent (below 10 ** -25) -> 553 Megabytes little/none -> 682 Megabytes Basically enough to store more than 200000 pages of text. >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? An audio CD can have a maximum of 99 tracks. There is basically no physical difference between an audio CD and a CD ROM. They even have logical similarities in addressing sectors. The main difference is that the data on an audio CD is always digitized sound and on a CD ROM it may not be. The discs are single sided and made from polycarbonate (the same stuff as in bullet proof windows). The two types of disks can be read with the same drive (Hitachi makes one right now) "all" that is needed is a D/A convereter. Dan Ford -- --------------------------------------------------------------------- Daniel A. Ford daford@watdragon.uucp CS Department daford%watdragon@waterloo.csnet U. of Waterloo daford%watdragon%waterloo.csnet@csnet-relay.arpa
nishri@gpu.utcs.toronto.edu (Alex Nishri) (01/11/88)
>What exactly is the capacity of a standard size CD, both in bytes and >in playing time for music (assuming a standard speed)? CD-A can have up to 72 minutes of audio, but due to molding problems toward the outer edge of the disc, it is rare to see 60 minutes exceeded. (The 'audio' is actually in a spiral track which goes from the inside to the outside.) CD-ROM, which uses the same disc, track, speed and other physical specifications can store approximately 550 megabytes of data. The actual amount quoted in various sources varies both because the term 'megabytes' is not standard (is it 1000000 bytes, or 1000 times 1024 bytes or is it 1024 times 1024 bytes?) and because the amount of data you can store depends on the amount of error correcting & detecting overhead you have. If you are interested in the technical details "CD-ROM Review" has covered them. A good book to read is the 1987 Bradley CD-ROM book. Incidently, CD-ROM is one sided because CD-A is. CD-ROM gets its economies of scale by using the same glass mastering and the same disc pressing plants as does CD-A. Larger discs using the same technology are more expensive because they don't enjoy the economies of scale. A large optical disc can have one gigabyte worth of data on one side. There do exist two sided versions with two gigabytes worth of information. There also exists something called optical tape. The same kind of technology is used on a tape surface. Capacity is measured in hundreds of gigabytes ...
ns@CAT.CMU.EDU (Nicholas Spies) (01/11/88)
In article <1988Jan10.214104.7965@gpu.utcs.toronto.edu> nishri@gpu.utcs.UUCP (Alex Nishri) writes: > ... >There also exists something called optical tape. The same kind of technology >is used on a tape surface. Capacity is measured in hundreds of gigabytes ... ...so maybe the film "Mind Storms" was a _documentary_ after all... :-)
norman@a.cs.okstate.edu (Norman Graham) (01/12/88)
in article <1988Jan10.214104.7965@gpu.utcs.toronto.edu>, nishri@gpu.utcs.toronto.edu (Alex Nishri) says: > The actual amount quoted in > various sources varies both because the term 'megabytes' is not standard (is > it 1000000 bytes, or 1000 times 1024 bytes or is it 1024 times 1024 bytes?) Of course the term 'megabyte' is standard and means 2^20 = 1024 * 1024, just as a KByte is standard and means 2^10 = 1024 and a gigabyte means 2^30. But this by no means keeps people from misusing the terms.
howard@cpocd2.UUCP (Howard A. Landman) (01/13/88)
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.
mark@cygnet.CYGNETSYSTEMS (Mark Quattrocchi) (01/15/88)
In article <10820001@hpsal2.HP.COM> hull@hpsal2.HP.COM (James Hull) writes: >> What exactly is the capacity of a standard size CD, both in bytes and >> in playing time for music (assuming a standard speed)? >> Nathan Glasser > >A CD can hold approximately 75 minutes of music (on one side). > >HP has a CD-ROM product which claims to hold "over 550 megabytes" on a >"three-mile long spiral track with a density of 16,000 tracks per inch". >The pictures in the brochure definitely show labeling on one side of the disc, >so I assume that only one side is being used for data. > > -- Jim Hull > hplabs!hpda!hull Both CD-ROM and WORM drives can hold between 500-750 meg depending on the manufacturer. It is expected within a year both will be able to hold 1 gig (double sided of course).
mark@cygnet.CYGNETSYSTEMS (Mark Quattrocchi) (01/15/88)
In article <1988Jan10.214104.7965@gpu.utcs.toronto.edu> nishri@gpu.utcs.UUCP (Alex Nishri) writes: > >>What exactly is the capacity of a standard size CD, both in bytes and >>in playing time for music (assuming a standard speed)? > >CD-A can have up to 72 minutes of audio, but due to molding problems toward the >outer edge of the disc, it is rare to see 60 minutes exceeded. (The 'audio' is >actually in a spiral track which goes from the inside to the outside.) > >CD-ROM, which uses the same disc, track, speed and other physical specifications >can store approximately 550 megabytes of data. The actual amount quoted in >various sources varies both because the term 'megabytes' is not standard (is >it 1000000 bytes, or 1000 times 1024 bytes or is it 1024 times 1024 bytes?) and >because the amount of data you can store depends on the amount of error >correcting & detecting overhead you have. If you are interested in the >technical details "CD-ROM Review" has covered them. A good book to read is >the 1987 Bradley CD-ROM book. Incidently, CD-ROM is one sided because CD-A >is. CD-ROM gets its economies of scale by using the same glass mastering and >the same disc pressing plants as does CD-A. > >Larger discs using the same technology are more expensive because they don't >enjoy the economies of scale. A large optical disc can have one gigabyte worth >of data on one side. There do exist two sided versions with two gigabytes worth >of information. > And if you want even higher capacity you can buy one of our jukeboxes which can hold up to 242 gigabyes. >There also exists something called optical tape. The same kind of technology >is used on a tape surface. Capacity is measured in hundreds of gigabytes ...
jack@cs.hw.ac.uk (Jack Campin) (01/21/88)
Expires: Sender: Followup-To: >>There also exists something called optical tape. The same kind of technology >>is used on a tape surface. Capacity is measured in hundreds of gigabytes ... > The January Scientific American mentions a *magnetic* tape drive used for very- long-baseline radio interferometry that records on 512 tracks at a rate of 256 megabits/second onto twelve-hour reels. I think that's more! -- ARPA: jack%cs.glasgow.ac.uk@nss.cs.ucl.ac.uk JANET:jack@uk.ac.glasgow.cs USENET: ...mcvax!ukc!cs.glasgow.ac.uk!jack Mail: Jack Campin, Computing Science Department, University of Glasgow, 17 Lilybank Gardens, Glasgow G12 8QQ, Scotland (041 339 8855 x 6045)