Last-modified: 1998/12/20
Version: 2.08
Send corrections and updates to Andy McFadden (fadden@netcom.com). If you have a question you'd like to see answered in here, either post it to one of the comp.publish.cdrom newsgroups (if you don't have the answer), or send it to fadden@netcom.com (if you do).
This was originally developed as a Usenet newsgroup FAQ. If you'd like to check out the newsgroups, point your news reader at the following (or go to http://www.dejanews.com/ and read them with your web browser):
The "canonical" FAQ is available from http://www.fadden.com/cdrfaq/ in HTML format and from the MIT FAQ archives in plain text format. You can get an all-in-one-file version of the HTML in a .ZIP file.
If you're maintaining a translation, or just really want to know what has changed since the last update, you can get a set of context diffs in a .ZIP file.
Please DO NOT post copies of the HTML version on your web site. I keep getting e-mail from people reading versions that are several months old. You should include a link to the www.fadden.com site instead. Links are very much appreciated, since it can be difficult to find this site by keyword through some search engines (lots of CD-R vendor spam).
The last-modified date of each section is shown below the Subject line. The date format used is YYYY/MM/DD. The date stamps were added on 1998/04/06, so you won't find any older than that.
This version of the FAQ is generated automatically by faq2html, an application developed specifically for converting the plain ASCII version of the CD-Recordable FAQ to HTML. The program isn't generally available at this time.
You are visitor
to this page since June 1st, 1998.
This FAQ is Copyright (C) 1998 by Andy McFadden, All Rights Reserved.
Free distribution of the this FAQ is encouraged, as are conversions to HTML or other formats and translation to foreign languages, so long as no content is removed, and additions are clearly marked. The plain ASCII text and www.fadden.com HTML versions aren't restricted, but other conversions might be (the content is free, the presentation might not be). Check with the publisher.
The date and version number on the FAQ *are* considered part of the content that must not be removed. I occasionally get messages from people who don't realize that the copy they're reading is more than a year and a half old.
Caveat lector: the information here is derived from Usenet postings,
e-mail, and information on WWW sites. As such, it may well be DEAD WRONG,
and you are encouraged to verify it for yourself.
I take no responsibility for damaged hardware, CD-Rs turned into coasters or frisbees, time lost, or any other damages you incur as a result of reading this FAQ. Information on specific models of hardware and software is based on *opinions* of other users, not scientific studies. I am not an expert in this (or any other) field. Everything here could be a total malicious lie, and should be treated as such. You have been warned.
I don't get paid to plug anybody's software or equipment. The sections on "what XXX should I buy" are not here because I want to sway purchases one way or another, they're here because the questions are asked *a lot*, and the answers are pretty consistent. You are invited and encouraged to investigate the capabilities and reputations of all products.
The various product and company names are trademarks of their respective companies.
Visit http://www.clari.net/brad/copymyths.html for a mini-FAQ on copyright laws.
This document attempts to answer Frequently Asked Questions about CD-Recordable technology and related fields. It is a Usenet newsgroup FAQ, updated and posted around the middle of each month. The main foci are explaining CD-R technology, describing hardware and software solutions for creating audio CDs and CD-ROMs, and helping people find solutions to common problems.
The FAQ is heavily biased toward PCs and computer-based recorders, because that's what I'm most familiar with, but I have made an effort to include useful information for owners of other equipment. I don't anticipate the section on stand-alone audio CD recorders expanding greatly, because they're far simpler to operate than computer-based recorders, and most of the "must know" information about them is more appropriate in an FAQ on stereo systems or studio recording.
I don't usually address questions that can be phrased, "how do I make my software do this?" The answers to those should be in the manual that came with your software. In general, this is a collection of answers to specific questions, not a "how to" guide. I also don't try to track moving targets, like CD recorder firmware versions or software versions unless a specific release is especially interesting. Ditto for which recorders work with which packet-writing solutions.
This FAQ does not, and will not, cover DVD, DVD-ROM, DVD-R, DVD-RAM, DVD+RW, or any of the other formats in the ever-expanding DVD morass. Recordable DVD will likely be an altogether different proposition, and will probably require its own FAQ (presumably written by somebody else!).
Another minor update. I could get used to this. ;-)
Added section (6-7-6). There were scattered changes throughout; the diffs are online if you're really interested.
There are a few translations available.
Italian, by Simone Parca: http://users.iol.it/parsi/.
There was a Chinese translation of an early version of the FAQ, but it fell out of date and has since disappeared.
French, German, Italian, Portuguese, and Spanish translations can be done through http://babelfish.altavista.digital.com/cgi-bin/translate. This is an automatic language translator that is HTML-aware. It only translates the first part of each document, so it's not entirely helpful if you just want to read a translation, but it may make doing a full translation much easier. (I'm told the translation is pretty good for an automatic translator, but is still pretty rough. I don't want to post a translation that is inaccurate or misleading, so I'm not going to run the FAQ parts through AltaVista automatically.)
If you're interested in translating this FAQ, you are welcome to do so, but please respect the amount of work that I and others have put into it. Don't strip out whole sections, remove author attributions, or hide the revision date of the document. I don't think the terms in section (0-1) are terribly restrictive. If, for whatever reason, you can't keep up with every update of the English version, that's fine; all I ask is that you include a link to the www.fadden.com version, so that the current information is easily locateable. (Some commonly updated things, like the list of recorders in section (5-1), don't need much translation.) If you don't want to translate a particular section, just leave it in English.
If you want to start with an HTML version, use the pages from http://www.fadden.com/cdrfaq/.
If you do a translation, let me know and I'll put the URL here.
This FAQ covers the three newsgroups in the comp.publish.cdrom hierarchy, one for software, one for hardware, and one for multimedia. The names of the newsgroups imply that the intended topics are related to publishing material on CD-ROMs, but the current discussions cover most everything related to CD-Recordable devices.
Here are a few guidelines. These aren't hard and fast rules -- nobody died and put me in charge of making the rules -- but if you're not sure what the appropriate subject matter is then this may be helpful.
news:comp.publish.cdrom.hardware is the most popular of the groups. Appropriate material includes questions about past, current, and future CD-R devices. Asking for installation help or advice on what to buy is appropriate, as are questions about related hardware like SCSI adapters and CD-ROM drives. Some related newsgroups are:
news:comp.sys.ibm.pc.hardware.cd-romnews:comp.publish.cdrom.software is for discussions about software used to prepare material for and create CDs and CD-ROMs. Questions about how to do things with a specific piece of software belong here, as do "the CD-R software from XXX won't recognize my drive", and "does a program exist that does YYY". Some related newsgroups are:
news:comp.sys.ibm.pc.hardware.storage
news:comp.sys.ibm.pc.hardware.systems
news:comp.periphs.scsi
news:alt.cd-rom
news:alt.comp.periphs.cdr
news:linux.apps.cdwrite
news:alt.cd-romnews:comp.publish.cdrom.multimedia is for discussions about creating multimedia products on CD-ROMs. Questions about multimedia authoring software belong here, as do most production-type questions, e.g. "where can I go to get my CD pressed with jewel cases and glossy inserts?" Related newsgroups are:
news:linux.apps.cdwrite
news:comp.multimediaPlease try to keep cross-posting to a minimum. Broadcasting questions to 3 or 4 related newsgroups will increase the noise level and probably won't get you more answers.
news:rec.video.desktop
news:rec.video.professional
news:rec.photo.digital
news:misc.education.multimedia
Some general rules apply to all of the comp.publish.cdrom.* groups:
(1) Piracy of CD-ROM software or CDs: CD recorders can be used to make copies of copyrighted material, and while backups of data are legal, making or accepting copies from others most likely isn't. Whatever your opinion of the matter, software piracy and other copyright violations are illegal in most countries in the world, so requests and/or advertisements for pirated material should be kept off the newsgroup. Also, please don't start or participate in a debate about whether or not software piracy is bad. There have been hundreds of such debates over the past several years, and the only thing that either side has managed to prove is that piracy debates are a tremendous waste of time.
(2) Personal CD-R hardware and software sales: strictly speaking, these groups aren't appropriate for selling off your old hardware or software. Such things are best left in misc.forsale.computers.*, ba.market.computers, and related groups. Since many readers are in the market for new hardware, a limited number of clearly marked articles are tolerated. The common Usenet convention is to use "FS: HP4020i $400 obo" for "For Sale" messages and "WTB: HP4020i" for "Want To Buy" messages.
(3) CD-R product advertising: these groups by their nature are somewhat commercial. Many readers are in the market for new hardware or CD-R media, and for this reason a *limited* amount of retail/wholesale advertising is tolerated but discouraged. If you *clearly* mark your postings as advertisements, you will get relatively few complaints. Posting frequent and useless followups just to broadcast your 20-line signature will get you flamed and subsequently ignored. Feel free to send mail to people who post questions about product pricing and availability, but please don't create mailing lists and broadcast to everyone who posts.
(4) Other advertising: while it's certainly the case that most or all of the readers have a CD-ROM drive on a computer, the same could be said of almost every person reading news from a home computer today. Please keep ads in newsgroups that are more appropriate. Advertising the latest educational, game, or adult CD is inappropriate for these groups, as are "hot new Cyrix 686 PC" posts. Subtle attempts to advertise web sites ("golly, this looked really neat, so I thought I'd tell everyone") are more obvious than you might think.
(5) Spam: you cannot make money fast. That's life, get used to it. If the message involves putting your name at the top of a list of 5 or 10 people, don't post it. If it has an 800 or 888 number that a reader would call to hear more about your unique business opportunity, don't post it.
(6) Job postings: looking for job candidates on these newsgroups is a tolerated but generally futile exercise. Most of the readers are looking for or offering help on CD-Rs, not searching for a job. Try one of the other groups, like misc.jobs.offered.
(7) Binaries: as with most Usenet newsgroups, posting binary files (large or small) is inappropriate. If you want to make a binary file available to Usenet readers, send it to an appropriate alt.binaries newsgroup, and just post a pointer to it in the other group(s).
One final note: bear in mind that these groups are read by people all over the world. If you're looking for local retailers, be sure to specify what "local" is for you. Posting in English is the best way to ensure that you will get a response, but the readership is diverse enough that you will likely get a reply no matter what language you use. If you want to quote prices, specify the currency to avoid confusion (e.g. US$300 or CAN$300 or Y30000 or ...).
The first thing to do is look at the web pages for the products you're using. Sometimes there will be software or firmware updates, or pages with information on common problems. Scanning through news archives on servers like www.altavista.digital.com or www.dejanews.com will often turn up relevant material.
If you don't find anything, calling or sending an e-mail message to the technical support department for the product that is giving you trouble is a good second step. If you want to contact other users, posting a message to one of the Usenet newsgroups is a reasonable thing to do.
You will get faster, more accurate responses to questions if you include enough detail in your mail message or news posting. For most problems having to do with recording, you need to specify:
These are intended to be brief (if somewhat incomplete) answers to basic questions. More detailed information can be found later in the FAQ. For example, section (1-5), "How much can they hold?", is answered in far more detail in section (7-6).
CD-R is short for "CD-Recordable". Recordable CDs are WORM (Write Once, Read Multiple) media that work just like standard CDs. The advantage of CD-R over other types of optical media is that you can use the discs with a standard CD player. The disadvantage is that you can't reuse a disc.
A related technology called CD-Rewritable (CD-RW) allows you to erase discs and reuse them, but the media doesn't work in all players.
The CDs you buy in a store are pressed from a mold. CD-Rs are burned with a laser. They may look different (often green, gold, or blue instead of silver), they're less tolerant of extreme temperatures and sunlight, and they're more susceptible to physical damage. Whether CD-Rs or pressed CDs last longer is difficult to answer.
While they're not physically identical, they work just the same. Some CD players and CD-ROM drives aren't as good at reading CD-R and CD-RW discs as they are at reading pressed CDs, but by and large they work just fine.
By the way, you can't write data onto pressed discs. Buying a bunch of old CDs in the hopes of writing new stuff onto them is a bad idea. You have to buy blank CD-R or CD-RW media.
Yes. You can create CD-ROMs from data on your hard drive, and you can create new audio CDs from anything you can record into a WAV or AIFF sound file. With an audio-only CD-Recorder, which hooks up to your stereo system instead of your computer, you can record directly from CD, cassette, DAT, or whatever.
The CD-ROMs you produce will play in ordinary CD-ROM drives, and the audio CDs you create will work in your home or car CD player.
Writing to CD-Rs and CD-RWs requires a special drive. You can't write CDs with an ordinary CD-ROM drive.
Yes, both audio and data CDs can be duplicated. You can even create audio CDs that are compilations of other audio CDs (perhaps a personal "best of" disc).
Bear in mind that most CDs are protected by copyright laws.
About 74 minutes of audio, or about 650MB of data.
Yes and no. The process can be a bit more involved than that, and requires special software that (usually) comes bundled with the drive.
With "packet writing" software, and a recorder that supports it, you can treat a CD-R or CD-RW disc like a floppy. Generally speaking, you can only write to each part of the disc once, so deleting files doesn't gain any space. There are other limitations as well.
With more traditional software -- necessary if you want the broadest possible compatibility -- you usually end up writing everything to the disc all at once. When you're doing the writing you can't interrupt the drive, and you can't reclaim the space you've used. If you want to write your files in smaller bunches, you lose a fair bit of space every time you stop and start again.
Nothing. This FAQ is about CD-R and CD-RW, and only crosses over into DVD when the two technologies rub up against each other.
To learn more about DVD, try http://www.unik.no/~robert/hifi/dvd/ (http://www.multimania.com/abela/DVD/DVDfaq.html if you prefer French).
This FAQ contains a great deal of information, but it's geared toward answering specific questions rather than providing a general education. Some of the other net resources are more like a tutorial than a Q&A list, and may provide a better starting point.
Mike Richter has a primer on CD-R at http://resource.simplenet.com/.
Octave's CD-Recordable Handbook is available in HTML from http://www.octave.com/library/ricoh/cdrhandbook.html.
Adaptec has a lot of information at http://www.adaptec.com/cdrec/.
I get a lot of questions about digital audio extraction that are answered at http://www.tardis.ed.ac.uk/~psyche/cdda/.
CD fundamentals.
From _The Compact Disc Handbook, 2nd edition_ by Ken Pohlmann, 1992 (ISBN 0-89579-300-8):
"Write-once media is manufactured similarly to conventional playback-only discs. As with regular CDs, they employ a polycarbonate substrate, a reflective layer, and a protective top layer. Sandwiched between the substrate and reflective layer, however, is a recording layer composed of an organic dye. .... Unlike regular CDs, a pre-grooved spiral track is used to guide the recording laser along the spiral track; this greatly simplifies recorder hardware design and ensures disc compatibility."
Your basic CD-R is layered like this, from top to bottom:
[optional] labelYes, it's real gold in "green" and "gold" CDs, but if you hold a CD-R up to a light source you'll notice that it's thin enough to see through (the gold layer is between 50 and 100nm thick). Something to bear in mind is that the data is closest to the label side of the CD, not the clear plastic side that the data is read from. If the CD-R doesn't have a hard top coating such as Kodak's "Infoguard", it's fairly easy to scratch the top surface and render the CD-R unusable.
[optional] scratch-resistant and/or printable coating
UV-cured lacquer
Reflective layer (24K gold or a silver-colored alloy)
Organic polymer dye
Polycarbonate substrate (the clear plastic part)
A laser in the CD recorder creates a series of holes in the disc's dye layer called "pits". The spaces between the pits are called "lands". The pattern of pits and lands on the disc encodes the information and allows it to be retrieved on an audio or computer CD player.
Discs are written from the inside of the disc outward. On a CD-R you can verify this by looking at the disc after you've written to it. The spiral track makes 22,188 revolutions around the CD, with roughly 600 track revolutions per millimeter as you move outward. If you "unwound" the spiral, it would be about 3.5 miles long.
The construction of a CD-RW is different:
[optional] labelSee the net references section for pointers to more data (especially http://www.cd-info.com/). http://www.araltd.com/whatscdr.html has some nice pictures, as do http://www.pc.be.philips.com/cdrw/general.html and http://www.nswc.navy.mil/cosip/nov97/cots1197-2.shtml.
[optional] scratch-resistant and/or printable coating
UV-cured lacquer
Reflective layer
Upper dielectric layer
Recording layer (the part that changes form)
Lower dielectric layer
Polycarbonate substrate (the clear plastic part)
See the net references section for pointers. The "CD Related Info" section on http://www.cdarchive.com/ has useful data, as does http://www.cd-info.com/ and the alt.cd-rom FAQ pages.
A quick summary of standards:
If you're not entirely put off by all this, pay a visit to http://www.emediapro.net/AprEM/parker4.html.
See http://www.cd-info.com/CDIC/Bibliography.html for information on where to get paper copies of the standards. You can download some of them from http://www.ecma.ch/. ECMA-119 describes ISO-9660, and ECMA-130 sounds a lot like "yellow book" if you say it slowly.
You can usually tell by looking at the packaging and/or the disc itself:
There are several possibilities; as yet no developers have come forward and announced what they're doing (for obvious reasons).
A simple and commonly seen technique is to increase the length of several files on the CD so that they appear to be hundreds of megabytes long. This is accomplished by setting the file length in the disc image to be much larger than it really is. The file actually overlaps with many other files. So long as the application knows the true file length, the software will work fine. If the user tries to copy the files onto their hard drive, or do a file-by-file disc copy, the attempt will fail because the CD will appear to hold a few GB of data. (In practice this doesn't foil pirates, because they always do image copies.)
One possible implementation, given sufficient control over the reader and mastering software, is to write faulty data into the ECC portion of a data sector. Standard CD-ROM hardware will automatically correct the "errors", writing a different set of data onto the target disc. The reader then loads the entire sector as raw data, without doing error correction. If it can't find the original uncorrected data, it knows that it's reading a "corrected" duplicate. This is really only viable on systems like game consoles, where the drive mechanism and firmware are well defined.
A less sophisticated but nonetheless effective method is to press a silver CD with data out beyond where a 74-minute CD can write. Copying the disc would then require special CD-R blanks, moving the data and hacking the disc to compensate, or pressing silver discs with the pirated data. If taken too far, though, the disc can become unreadable on some drives.
The approach PC software houses have taken lately is to use nonstandard gaps between audio tracks and leave index marks in unexpected places. These discs are uncopyable by most software, and it may be impossible to duplicate them on drives that don't support disc-at-once recording (see section (2-9)).
Another method gaining popularity is non-standard discs with a track shorter than 4 seconds. Most recording software, and in fact some recorders, will either refuse to copy a disc with such a track, or will attempt to do so and fail. A protected application would check for the presence and size of the track in question. Some recorders may succeed, however, so this isn't foolproof. (In one case, a recorder could write tracks that were slightly over three seconds, but refused to write tracks that were only one second. There may be a limit below which no recorder will write.)
Putting multiple data tracks interleaved with audio tracks on a CD will confuse some disc copiers.
Sometimes the copy of a disc will have a different volume label. This usually only happens with file-by-file copies, not disc image copies, so checking the disc name is marginally useful but not very effective.
Modifying the TOC so that the disc appears to be larger than it really is will convince some copy programs that the source disc is too large.
The Laserlok system from http://www.diskxpress.com/ claims to be able to prevent unauthorized disc duplication at a low cost. (VOB's CD-Wizard, listed in section (6-1-35), claims to be able to copy them.)
A recent innovation is TTR Technology's DiscGuard (http://www.ttr.co.il/). They claim to be able to write a signature onto pressed CDs and CD-Rs that is detectable by all CD-ROM drives but isn't reproducible without special hardware. A program could use this for copy protection by checking for the presence of the signature, and refusing to run if it's not there.
Sony DADC is promoting a simliar product called Securom. Some information is at http://www.sonydadc.com/hotnews/secu_fra.htm. Yet another variant is C-Dilla's SafeDisc[tm]; see http://www.c-dilla.com/ for more.
All of the above applies to CD-ROM discs. There is no way to copy protect an audio CD and still have it be playable in an audio CD player.
A separate but related issue is "counterfeit protection", where the
publisher wants to make it easy to detect mass-produced duplicates. An
example of this is Microsoft's placement of holograms on the hub of their
recent CD-ROMs.
A session is a recorded segment that may contain one or more tracks of any type. The CD recorder doesn't have to write the entire session at once, but the last session on a disc must be "closed" before a standard audio CD or CD-ROM player will recognize it. Additional sessions can be added until the *disc* is closed or there's no space left.
Multisession writing was first used on PhotoCD discs, to allow additional pictures to be appended. Today it's most often used with "linked" multisession discs, and occasionally for CD-Extra discs. These require a bit more explanation.
When you put a data CD into your CD-ROM drive, the OS finds the last session on the disc and reads the directory from it. (Well, that's how it's supposed to work. Depending on your operating system and CD-ROM drive, you may get different results.) If the CD is ISO-9660 format - which it almost certainly is unless it's a Macintosh CD written in HFS - the directory entries can point at any file on the CD, no matter which session it was written in.
Most of the popular CD creation programs allow you to "link" one or more earlier sessions to the session currently being burned. This allows the files from the previous sessions to appear in the last session without taking up any additional space on the CD (except for the directory entry). You can also "remove" or "replace" files, by putting the new version into the last session, and not including a link to the older version.
In contrast, when you put an audio CD into a typical CD player, it only looks at the first session. For this reason, multisession writes don't work for audio CDs, but as it happens this limitation can be turned into an advantage. See section (3-14) for details. This limitation does *not* mean you have to write an entire audio CD all at once; see section (2-9) for an overview of track-at-once writing.
Note that mixing MODE-1 (CD-ROM) and MODE-2 (CD-ROM/XA) sessions on a single disc isn't allowed. You could create such a thing, but many CD-ROM drives will have a hard time recognizing it.
See also http://www.adaptec.com/support/faqs/multisession.html, which goes into more depth.
Discs written with packets are an entirely different story. See section (6-3).
There are eight subcode channels (P,Q,R,S,T,U,V,W). The exact method of encoding is beyond the scope of this FAQ, but it should be noted that the data is distributed uniformly across the entire CD, and each channel can hold a total of about 4MB.
The P subcode channel can be controlled with the JVC/Pinnacle recorders, but apparently isn't used for much.
The Q subcode channel includes useful information, which can be read and written on many recorders. The user data area contains three types of subcode-Q data: position information, media catalog number, and ISRC code. Other forms are found in the lead-in, and are used to enable multisession and describe the TOC (table of contents).
The position information is used by audio CD players to display the current time, and has track/index information. This can be controlled when doing Disc-At-Once recording.
The ISRC (International Standard Recording Code) is used by the recording industry. It states the country of origin, owner, year of issue, and serial number of tracks, and may be different for each track. It's optional; many CDs don't use this. The media catalog number is similar, but is constant per disc. Note these are different from the UPC codes.
The R-W subcode channels are used for text and graphics in certain applications, such as CD+G (CD w/graphics, supported by SegaCD among others). A new use has been devised by Philips, called ITTS. It enables properly equipped players to display text and graphics on Red Book audio discs. The most recent result of this technology is "CD-Text", which provides a way to embed disc and track data on a standard audio CD.
The other subcode channels are generally inaccessible and unused.
For more details, see the book by Pohlmann mentioned in section (2-1); _Principles of Digital Audio_, 3rd edition, by Ken Pohlmann, McGraw-Hill, 1995 (ISBN 0-07-050469-5); or _The Art of Digital Audio_, 2nd edition, by John Watkinson, Focal Press, 1994 (ISBN 0-240-51320-7).
At present, not many manufacturers use them, and not all devices can read all of the fields.
It depends on how much data you're going to burn, and how fast your drive is. Burning 650MB of data takes about 74 minutes at 1x, 37 minutes at 2x, and 19 minutes at 4x, but you have to add a minute or two for "finalizing" the disc. Remember that single speed is 150KB/sec, double speed is 300KB/sec, and so on.
If you have half the data, it will finish in (about) half the time.
There are two basic ways of writing to a CD-R. Disc-at-once (DAO) writes the entire CD in one pass, possibly writing multiple tracks. The entire burn must complete without interruption, and no further information may be added.
Track-at-once (TAO) allows the writes to be done in multiple passes. There is a minimum track length of 300 blocks (600K for typical data CDs), and a maximum of 99 tracks per disc, as well as a slight additional overhead associated with stopping and restarting the laser.
Because the laser is turned off and on for every track, the recorder leaves a couple of blocks between tracks, called run-out and run-in blocks. If done correctly, the blocks will be silent and usually unnoticeable. CDs with tracks that run together will have a barely noticeable "hiccup". Some combinations of software and hardware may leave junk in the gap, resulting in a slight but annoying click between tracks. Some drives and/or software packages may not let you control the size of the gap between audio tracks when recording in track-at-once mode, leaving you with 2-second gaps even if the original didn't have them.
A few recorders, such as the Philips CDD2000, allow "session-at-once" recording. This gives you disc-at-once control over the gaps between tracks, and allows you to write in more than one session. This can be handy when writing CD Extra discs (see section (3-14)).
There are some cases where disc-at-once recording is required. For example, it may be difficult or impossible to make identical backup copies of some kinds of discs without using disc-at-once mode (e.g. copy-protected PC games). Also, some CD mastering plants may not accept discs recorded in track-at-once mode, because the gaps between tracks will show up as errors.
The bottom line is that disc-at-once recording gives you more control over disc creation, especially for audio CDs, but isn't always appropriate or necessary. It's a good idea to get a recorder that supports both disc-at-once and track-at-once recording.
Many CD-R creation packages will give you a choice between creating a complete image of the CD on disk and doing what's called "on-the-fly" writing. Each method has its advantages.
Disc image files are sometimes called virtual CDs or VCDs (not to be confused with VideoCD). These are complete copies of the data as it will appear on the CD, and so require that you have enough hard drive space to hold the complete CD. This could be as much as 650MB for CD-ROM or 747MB for an audio disc when using 74-minute blanks. If you have both audio and data tracks on your CD, there would be an ISO-9660 filesystem image for the data track and one or more 16-bit 44.1KHz stereo sound images for the audio tracks.
(On the Mac, you might instead use an HFS filesystem for the data track. You can create the image with Mac CD recording software, or create it as a DiskCopy image file and then burn the data fork under a different OS. The DiskCopy method doesn't seem to allow you to create bootable CD-ROMs though.)
On-the-fly recording often uses a "virtual image", in which the complete set of files is examined and laid out, but only the file characteristics are stored, not the data. The contents of the files are read while the CD is being written. This method requires less available hard drive space and may save time, but increases the risk of buffer underruns (see (4-1)). With most software this also gives greater flexibility, since it's easier to add, remove, and shuffle files in a virtual image than a physical one.
A CD created from an image file would be identical to one created with on-the-fly recording, assuming that both would put the same files in the same places. The choice of which to use depends on user preference and hardware capability.
There are subcode flags for each track:
CD-RW is short for CD-Rewritable. It used to be called CD-Erasable (CD-E), but some marketing folks changed it so it wouldn't sound like your important data gets erased on a whim. The difference between CD-RW and CD-R is that CD-RW discs can be erased and rewritten, while CD-R discs are write-once. Other than that, they are used just like CD-R discs.
CD-RW drives use phase-change technology. Instead of creating "bubbles" and deformations in the recording dye layer, the state of material in the recording layer from crystalline to amorphous form. The different states have different refractive indicies, and so can be optically distinguished.
These discs are not writable by standard CD-R drives, nor readable by most older CD readers (the reflectivity of CD-RW is far below CD and CD-R, so an Automatic Gain Control circuit is needed to compensate). All CD-RW drives can write to CD-Rs, and most new CD-ROM drives are expected to support CD-RW. (Reports have indicated that CD-RW discs don't always read at full speed on some drives, however.)
A few older audio CD players and many new ones can handle CD-RW discs, but many can't. If you want to create audio CDs on CD-RW media, make sure that your player can handle them.
Oddly enough, it may be easier for a DVD drive to read CD-RW discs than CD-R discs, because of the way the media is constructed.
CD-RW media is much more expensive than CD-R. This has been improving, but is still a factor in purchase decisions. There is a limit to the number of times an area of the disc can be rewritten, but that number is relatively high (the Orange Book requires 1000, but some manufacturers have claimed as much as 100,000).
For an *excellent* description of the technology, see http://www.onlineinc.com/cdrompro/0996CP/bennett9.html.
A technical discussion along with some handy drawings and graphs is available from http://www.pc.be.philips.com/cdrw/general.html.
Some interesting articles on CD-RW - including an editorial critical of the new technology - can be found at:
http://www.emediapro.net/JanEM/news1.html#eraseIf you're trying to decide if you want a drive that supports CD-RW, see section (5-16).
http://www.emediapro.net/FebEM/writer2.html
http://www.emediapro.net/AprEM/parker4.html#bennett
The only discs that a DVD drive is guaranteed to read are DVD discs. Support for CD-ROM, CD-R, and CD-RW may be included, but is by no means guaranteed.
CD-R was designed to be read by an infrared 780nm laser. DVD uses a visible red 635nm or 650nm laser, which aren't reflected sufficiently by the organic dye polymers used in CD-R media. Some DVD players come with two lasers so that they can read CD-R.
Some DVD drives may be unable to read multisession discs.
If the box doesn't say that something is supported, assume that the feature isn't. Look for the MultiRead logo, which indicates that the DVD player can read all existing CD formats, including CD-ROM, CD-DA, CD-R and CD-RW.
[ I verified that the Sony DVP-S3000 can read CD-R media, though the manual didn't say anything about them. It plays audio CDs and VideoCDs off CD-R just fine. I'm told that the Sony models include two lasers -- Dual Discrete pickup -- but most of the others don't. I'm not planning on starting a compatibility list, so if you plan to buy a DVD player and CD-R compatibility is important, bring an audio or VideoCD CD-R with you to the store and try to play it. ]
Probably not. The recorders are still very expensive, and the format wars are ongoing.
An example: http://www.electroweb.com/product/hard.htm was, as of early February '98, selling a Pioneer CDVR-S101 DVD-Recordable Drive for $18K. As mentioned in section (0-2), this FAQ will not be expanding to cover DVD recorders.
Other formats like DVD-RAM are available for less, but may not be compatible with current DVD players.
The first thing to know is that there are two kinds of jitter that relate to audio CDs. The usual meaning of "jitter" refers to a time-base error when digital samples are converted back to an analog signal; see http://www.digido.com/jitteressay.html for a discussion. The other form of "jitter" is used in the context of digital audio extraction from CDs. This kind of "jitter" causes extracted audio samples to be doubled-up or skipped entirely. (Some people will correctly point out that the latter usage is an abuse of the term "jitter", but we seem to be stuck with it.)
"Jitter correction", in both senses of the word, is the process of compensating for jitter and restoring the audio to its intended form. This section is concerned with the (incorrect use of) "jitter" in the context of digital audio extraction.
The problem occurs because the Philips CD specification doesn't require block-accurate addressing. While the audio data is being fed into a buffer (a FIFO whose high- and low-water marks control the spindle speed), the address information for audio blocks is pulled out of the subcode channel and fed into a different part of the controller. Because the data and address information are disconnected, the CD player is unable to identify the exact start of each block. The inaccuracy is small, but if the system doing the extraction has to stop, write data to disk, and then go back to where it left off, it won't be able to seek to the exact same position. As a result, the extraction process will restart a few samples early or late, resulting in doubled or omitted samples. These glitches often sound like tiny repeating clicks during playback.
On a CD-ROM, the blocks have a 12-byte sync pattern in the header, as well as a copy of the block's address. It's possible to identify the start of a block and get the block's address by watching the data FIFO alone. This is why it's so much easier to pull single blocks off of a CD-ROM.
With most CD-ROM drives that support digital audio extraction, you can get jitter-free audio by using a program that extracts the entire track all at once. The problem with this method is that if the hard drive being written to can't keep up, some of the samples will be dropped. (This is similar to a CD-R buffer underrun, but since the output buffer used during DAE is much smaller than a CD-R's input buffer, the problem is magnified.)
Some CD-ROM drives, e.g. most of the Plextor models, include special circuitry that enables them to accurately detect the start of a block.
An approach that has produced good results is to do jitter correction in software. This involves performing overlapping reads, and then sliding the data around to find overlaps at the edges. Most DAE programs will perform jitter correction.
I don't have a favorite book or web site to recommend. Poke around on the http://www.cd-info.com/ web site, especially some of the books and links listed in the bibliography.
Actually, they do. It is true that audio CDs use all 2352 bytes per block for sound samples, while CD-ROMs use only 2048 bytes per block, with most of the rest going to ECC (Error Correcting Code) data. The error correction that keeps your CDs sounding the way they're supposed to, even when scratched or dirty, is applied at a lower level.
All of the data written to a CD uses CIRC (Cross-Interleaved Reed-Solomon Code) encoding. Every CD has two layers of error correction, called C1 and C2. C1 corrects bit errors at the lowest level, C2 applies to bytes in a frame (24 bytes per frame, 98 frames per block). In addition, the data is interleaved and spread over a large arc. (This is why you should always clean CDs from the center out, not in a circular motion.)
If there are too many errors, the CD player will interpolate samples to get a reasonable value. This way you don't get nasty clicks and pops in your music, even if the CD is dirty and the errors are uncorrectable. Interpolating adjacent data bytes on a CD-ROM wouldn't work very well, hence the need for additional ECC and EDC (Error Detection Codes).
See http://www.onlineinc.com/cdrompro/0296CP/02parkerstarrett.html if you want to know more.
MiniDiscs, or MDs, are small (64mm) discs that hold about 140MB of data or 160MB of audio. By using sophisticated compression techniques they are able to compress audio by a 5:1 ratio, allowing a capacity of 74 minutes with little or no audible difference in quality. As with CD recorders, there are MD recorders that connect to your computer and MD recorders that connect to your stereo.
There are stamped MDs that are similar to CDs in construction, and rewritable MDs that use magneto-optical technology. Audio MD recorders are generally more convenient than stand-alone audio CD recorders, because the playback mechanism allows a more flexible layout of audio data, so it's possible to delete a track from the middle of the MD and then write a longer one that is recorded in different places across the disc. The current generation of MD technology is unlikely to replace CD-R or DAT, however, because the lossy compression employed is disdained by audio purists. MD is more often positioned as a replacement for analog cassette tape, which it matches in portability and recordability, and surpasses in durability and its ability to perform random accesses.
Computer-based MD recorders can write data, but may not be able to record audio. Check the specifications carefully.
A wealth of information is available from http://www.minidisc.org/. If you want to transfer CD to MD or MD to CD-R, check the FAQ there for information about digital transfers (currently item #37).
A disc that you can add data to is "open". All data is written into the current session. When you have finished writing, you close the session. If you want to make a multisession disc, you open a new session at the same time. If you don't open a new session then, you can't open one later, which means that it's impossible to add more data to the CD-R. The entire disc is considered "closed".
The process of changing a session from "open" to "closed" is called "finalizing", "fixating", or just plain "closing" the session. When you close the last session, you have finalized, fixated, or closed the disc.
A single-session disc has three basic regions: the lead-in, which has the Table of Contents (or TOC); the program area, with the data and/or audio tracks; and the lead-out, which doesn't have anything meaningful in it. An "open" disc doesn't yet have the lead-in or lead-out written.
If you write data to a disc and leave the session open, the TOC -- which tells the CD player or CD-ROM drive where the tracks are -- is written into a separate area called the Program Memory Area, or PMA. CD recorders are the only devices that know to look at the PMA, which is why you can't see your data in an open session on a standard playback device. CD players won't find any audio tracks, and CD-ROM drives won't see a data track. When the session is finalized, the TOC is written in the lead-in area, enabling other devices to recognize the disc.
If you close the current session and open a new one, the lead-in of the closed session will include a link to the lead-in of the next. The CD player in your car or stereo system doesn't know about chasing from one lead-in to the next, so it can only see tracks in the first session. Your CD-ROM drive, unless it's broken or fairly prehistoric, will know about multisession discs and will happily return the first session, last session, or one somewhere in between, depending on what the OS tells it and what it is capable of.
Some CD-ROM drives, notably certain NEC models, are finicky about open sessions, and will gag when they try to read the lead-in from a still-open session. They follow the chain of links in the lead-ins of each session, but when they get to the last, they can't find a valid TOC and become confused. Even though these drives support multi-session, they require that the last session be closed before they will read the disc successfully. Fortunately most drives don't behave this way.
If you use disc-at-once recording, the lead-in is written at the very start of the process, because the contents of the TOC are known ahead of time. With most recorders there is no way to specify that an additional session should be added, so creating a multisession disc with DAO recording isn't generally possible.
If you're using Win95 or WinNT, the Auto Insert Notification feature will "discover" the CD-R as soon as the TOC is written. This usually causes the write process to fail. Many of the current CD recording software packages will automatically disable AIN for this reason. In track-at-once mode, it will fail during finalization; in disc-at-once mode, it will fail near the beginning of the write process. In both cases, test writes will succeed, because the TOC doesn't get written during a test pass.
Packet-written discs follow the same rules with regard to open and closed sessions, which is why they have to be finalized before they can be read on a CD-ROM drive. The "Packet Writing - Intermediate" document in the primer at http://resource.simplenet.com/primer/primer.htm goes into a little more detail on this subject.
There are gory details beyond what is written here. For example, the lead-in on a CD-R actually has a pre-recorded TOC that specifies physical parameters of the recording layer, such as required laser recording power, and information about the disc, like how many blocks can be written. You don't usually need to worry about such things though.
There is absolutely nothing special about the audio data encoded on a CD. The only difference between a "raw" 44.1KHz 16-bit stereo WAV file and CD audio is the byte ordering.
It isn't necessary to convert a WAV or AIFF file to a special format to write to a CD, unless you're using some proprietary coding (like MP3 compression) that doesn't have a system-recognized codec. Similarly, you don't have to do anything special to audio extracted from a CD. It's already in a format that just about anything can understand.
Just put your audio into the correct format -- 44.1KHz, 16-bit, stereo, uncompressed (a/k/a PCM) -- and the software you use to write CDs will do the rest. All of the fancy error correction and track indexing stuff happens at a lower level.
The MultiRead logo indicates that a CD or DVD player can read all existing CD formats, including CD-ROM, CD-DA, CD-R and CD-RW. See the press release at http://www2.osta.org/osta/html/press/pr150797.html. The presence of this logo on a CD-ROM drive does *not* mean that the drive can read DVD.
That depends on what was being recorded, how it was being recorded, and how far along in the process things were.
If it failed while writing the lead-in, before any data was written, the disc probably isn't usable. Sony drives have a "repair disc" option that forcefully closes the current session, which would allow you to add extra data in a second session on the disc, but most recorders will refuse to touch a disc that's in a partially-written state.
Failures when finalizing the disc may be correctable. Sometimes the TOC gets written before the failure, and the disc can be used as-is. Sometimes you can use a "finalize disc" option from a program menu that will do the trick. Other times the recorder will refuse to deal with a partially-finalized disc, and you're stuck.
Failures in the middle of writing result in a CD-ROM that probably isn't worth trusting. Some of the data will be there, some won't. The directory for the disc may show more files than are actually present, and you won't know which are actually there until you try to read them.
Audio CDs recorded in disc-at-once mode are a special case. Because the TOC is written up front, the disc is readable in a standard CD player even if the write process doesn't finish. You will be able to play the tracks up to the point where the recording failed.
If you were using a packet writing program like DirectCD, the experiences of people on Usenet suggest that you are either 100% okay or 100% screwed. The ScanDisk utility included with DirectCD 2.5 may help though.
This phenomenon is familiar to users who have attempted to extract digital audio from a CD-R. Very often the result of copying an audio CD is an exact copy of the original audio data, but with a few hundred zero bytes inserted at the front (and a corresponding number lost off the end). Since this represents the addition of perhaps 1/100th of a second of silence at the start of the disc, it's not really noticeable.
The actual number of bytes inserted may very slightly from disc to disc, but a given recorder usually inserts about the same number. It's usually less than one sector (2352 bytes).
According to a message from a Yamaha engineer, the cause of the problem is the lack of synchronization between the audio data and the subcode channels, much like the "jitter" described in section (2-15). The same data flow problems that make it hard to find the start of a block when reading also make it hard to write the data and identifying information in sync. According to the engineer, no changes to the firmware or drive electronics can fix the problem.
Making copies of copies of audio CDs would result in a progressively larger gap, but it's likely to be unnoticeable even after several generations.
This is general information about recommended ways to do specific tasks.
Several publishers have CD-to-CD copiers. Two low-cost versions for the PC are Adaptec EZ-SCSI, which comes with a simple CD copier called "CD Copier", and Jeff Arnold's freeware CD2CD (http://www.goldenhawk.com/). Mac users can get a product called CD-Copy from Astarte (http://www.astarte.de/).
The easiest and most reliable method to make copies of single-track data CDs is also the least expensive: CD2CD runs under DOS and works very well with a wide variety of hardware.
Software such as Arnold's and Adaptec's will allow you to make a CD image on a hard drive that can then be written to multiple CDs.
The fancier packages will usually provide a way to do this as well, but the software tends to be more complicated and harder to use. Multi- session and other complicated formats require more sophisticated software, such as Jeff Arnold's SNAPSHOT or CDRWIN.
It's important to remember that, when copying directly from one CD to another, the source MUST be faster than the target, and must be error-free. If the source pauses or spins down to read a marginal area of the disc, the target may outrun the source, and the CD-R will only be useful as a frisbee. Most programs have a "test write" feature that put the CD-R device into a mode where it goes through all the motions but doesn't actually write anything; it's a good idea to do this right before copying.
CDs don't have circular tracks. They're laid out on a spiral, with multiple sessions composed of multiple tracks composed of sectors, and the data in the sectors is interleaved and spread over a large area. The sector format is standard, but there's more than one standard.
"The nice thing about standards is that there's so many to choose from."
-- Andrew S. Tanenbaum
The ability to read certain portions of a CD depends on the CD firmware. Some CD players aren't capable of understanding multi-session discs or of reading audio tracks as digital data. Jitter, described in section (2-15), is also a problem for most drives.
Start with the CD-DA FAQ: http://www.tardis.ed.ac.uk/~psyche/cdda/.
To copy from CD to CD, the source drive needs to support digital audio extraction, which is rather rare among older drives. A copier such as Adaptec's "CD Copier" will copy the CD track-by-track, while one like Jeff Arnold's CDRWIN will use disc-at-once recording.
Some programs will only copy the CD to the hard drive and from there to CD-R, some will allow CD-to-CD directly but only if the source is a SCSI CD-ROM, and some will work with IDE or SCSI. As with copying CD-ROMs, you must be able to read data off of the source drive faster than your recorder is writing. If you can only extract audio at 1x, you're not going to be able to do a CD-to-CD copy reliably.
If you're just interested in extracting digital audio, you don't even need a CD-R unit, just a CD-ROM drive that supports DA extraction and some software. The CD-DA site shown at the top of this section lists some drives that support it, has a place to submit results for your own drive, and has links to inexpensive or free DAE software.
Different drives can extract digital audio at different speeds. For example, the Plextor 6Plex can extract audio at 6x, while the NEC 6Xi can only extract at 1x. The Plextor UltraPlex has been clocked at over 20x.
Some CD-ROM and CD-R drives have trouble extracting digital audio at high speed, so if you're getting lots of clicks and pops when extracting you should try doing it at a slower speed. You may also run into trouble if you try to extract faster than your hard drive can write. One user found that he was able to eliminate clicks and pops by defragmenting his hard drive. Another found that the Win95 "vcache" fix (section (4-1-2)) solved his problems.
It should be pointed out that, while digitally extracted audio is an exact copy of the data on the CD, it's an exact copy as your CD player perceives it. Different drives or different runs with the same drive can extract slightly different data from the same disc. The differences are usually inaudible, however.
The quality of the CD-R audio output depends mostly on how well your CD player gets along with the brand of media you're using. See the next section for some comments about avoiding clicks and pops.
Some drives have trouble starting at the exact start of audio tracks. The extraction starts a few blocks forward of where it should, and ends a few blocks later, so the track may not sound quite right and the extraction program will report errors at the end of the last track. See section (4-19).
One minor note: the data on audio CDs is stored in "Motorola" big-endian format, with the high byte of each 16-bit word first. AIFF files also use this format, but WAV files use "Intel" little-endian format. Make sure your software deals with the endian-flipping correctly. Byte-swapped CD audio sounds like noise.
If you're interested in removing noise from audio captured from an analog source, such as a record player or analog cassette tape, skip to section (3-12). This section is about unexpected noise in audio from digital sources, such as tracks extracted from a CD.
The single most important rule of noise removal is to figure out where the noise came from. Play the .WAV files off of your hard drive (if you're doing direct CD-to-CD copies, extract a track and listen to it). If you hear noise in the .WAV on your hard drive, the digital audio extraction isn't working very well. You either need to extract more slowly, extract from a different device, find a program that works better, or maybe just clean the dust and grime off the source CD. For more information, including a URL for the CD-DA FAQ, see section (3-2).
If the problem sounds like repeated or skipped samples, rather than clicks or hissing, the problem is probably jitter during extraction. See section (2-15) for an overview.
A nifty trick for comparing two .WAV files is to use the "Mix Paste" feature in Cool Edit. Extract a track twice, then use Mix Paste to copy an inverted version of one file on top of the other. The two sound files will cancel each other out wherever they are identical, and have little spikes where they are different. This can be useful for seeing if the problems are only on one channel or are happening at regular intervals. You need to make sure though that both files start at the same place though. If your CD-ROM drive doesn't always extract from the start of the block, you will need to adjust the files so they line up.
Useful things to do with this include comparing two extractions from the same drive, extractions from different drives, or extractions from the CD-R you just wrote to the original .WAV file you used to write it.
If you just want to see if the files are the same, use the DOS File Compare command, with the "binary" switch set: FC /B FILE1.WAV FILE2.WAV.
Some CD-ROM drives may put a click a few seconds into the first track being extracted. This appears to be related to the drive spinning up. Try starting the extraction, cancelling, and then immediately restarting.
The rest of this section only applies if the extracted audio sounds fine on disk, but has problems when played back from the CD-R.
If you're using track-at-once recording, you may get a short click or
silent "hiccup" at the start of each track. Hiccups are unavoidable, but
you should be able to get rid of the click by using different software.
If you're using disc-at-once recording, and are still getting a short click at the *start* of every track, then your recording software is probably writing the sound file with the headers still on it. You should either use a smarter program, or remove the header manually (see the URL for "WAVECLIP", below).
If you are getting clicks in the middle of a track, they are either being added when pulling the data off the disc or when writing it. If the .WAV (AIFF on the Mac) file plays without clicks, then your CD recorder may be failing somehow during the write process. Some people who got "static" in audio recorded on an HP 4020i found that reducing the DMA transfer rate to 2MB/sec helped.
If you are getting clicks at the end of a track, it's possible that the software used to create the .WAV file put some information at the very end, which is legal but not handled correctly by some CD-R software. See section (3-12) for tips on using CoolEdit to remove the data. If you are finding that tracks extracted from CDs don't have clicks but tracks that you have recorded or edited do, chances are the data size isn't a multiple of 2352 bytes, and the last block is being filled with junk. This is common on live recordings or when large tracks are cut into smaller ones. Jeff Arnold's DAO will fill out the last block with zeros (digital silence) if there is space left over, but most of the other programs will write garbage that is audible as a short (less than 1/75th second) click. The fix is to split the track on 2352-byte block boundaries.
A program called "WAVECLIP" will remove .WAV headers and footers, and will either pad out the last block or remove silence from the end of a WAV file to make it an exact multiple of 2352 bytes. The program is available from http://www.ptialaska.net/~syntec/waveclip.zip. Another choice is "StripWave", from http://www.lightlink.com/tjweber/.
If you must use track-at-once, make sure you're writing it all in one
session. PC-based CD players may be able to see tracks in later sessions,
but the CD player in your stereo system can't.
A distantly related problem can arise if you use "shuffle play" to play random tracks from a CD-R. If the audio of track N begins immediately, some CD players will slide from the end of track N-1 into the start of track N, playing a short burst of track N before seeking elsewhere. This can be avoided by putting a gap at the start of such tracks (e.g. with "INDEX 01 xx:yy:zz" in a DAO cue sheet).
Jeff Arnold has a utility called CDRWIN that can do this; see his web page at http://www.goldenhawk.com/.
Note that this software does NOT defeat the copy protection. (I'm told that the "copy protection" is in fact a region code -- America, Europe, Japan -- printed as a barcode on the CD hub. The "MOD chip" sold to defeat the copy protection emulates the barcode reading process, and sends all three region codes back, enabling the game console to play discs from other regions as well as copied discs.)
Instructions for copying discs and vendors who sell MOD chips can be found by searching the net. If you don't have a PC, or if your drive doesn't support disc-at-once recording, you will need to look for disc copying instructions on the net.
Sega Dreamcast discs reportedly use a proprietary format that can hold 1GB of data. This could make them difficult or impossible to copy.
Incidentally, posting requests or advertisements for pirated software on one of the Usenet groups is generally regarded as a mark of extreme stupidity. Whatever your opinion of software piracy, it is against the law in much of the world.
There are several different ways, most of which only work with some operating systems. The next few sections discuss the various methods.
See http://www.adaptec.com/tools/compatibility/cdrecfilename.html for a detailed description with some examples.
Getting mixed-case filenames onto a disc is a similar problem. Burning an ISO-9660 disc with lower-case filenames isn't recommended, because some systems aren't able to access the files even though they appear in directory listings.
"mkhybrid" and recent versions of "mkisofs" (1.12b1 or later), described in sections (6-1-32) and (6-1-10), respectively, are able to create CDs that have both Joliet and Rock Ridge extensions.
Level 1 ISO-9660 defines names to be the familiar 8+3 convention that MS-DOS users have suffered through for many years: eight characters for the name, a period ("full stop" for those of you in the U.K.), followed by three characters for the file type, all in upper case. The only allowed characters are A-Z, 0-9, '.', and '_'. There's also a file version number, separated from the name by a semicolon, but it's usually ignored.
Files must occupy a contiguous range of sectors. This allows a file to be specified with a start block and a count. (Most disk-based filesystems require index blocks that list all the blocks used by a file.) The maximum directory depth is 8.
Level 2 ISO-9660 allows far more flexibility in filenames, but isn't usable on some systems, notably MS-DOS.
Level 3 ISO-9660 allows non-contiguous files, useful if the file was written in multiple packets with packet-writing software.
Some of the CD creation programs will let you select how closely you want the CD to conform to the ISO-9660 standard. For example, Easy-CD Pro 95 can restrict filenames to be ISO-9660 compliant, or allow the full set of valid MS-DOS filenames. (Most systems can handle MS-DOS filenames.)
Incidentally, the ISO-9660 spec requires that all files be displayed in alphabetical order, with directories first, no matter how they are recorded on the CD-ROM. You can't arrange files on the disc, because the ISO-9660 reader (e.g. MSCDEX) sorts them before displaying them.
The Rock Ridge extensions to ISO-9660 define a way for UNIX-isms like long mixed-case filenames and symbolic links to be supported.
Because it's still an ISO-9660 filesystem, the files can still be read by machines that don't support Rock Ridge; they just won't see the long forms of the names.
Rock Ridge is supported by UNIX systems. DOS, Windows, and the Mac don't currently support it.
Copies of the Rock Ridge standard and System Use Sharing Protocol (SUSP) can be found at ftp://ftp.ymi.com/pub/rockridge/. Pay a visit to http://makecd.core.de/Rock_Ridge_Amiga_Specific for a description of Amiga-specific extensions.
HFS is the Hierarchical File System, used by the Macintosh. This is used in place of the ISO-9660 filesystem, making the disc unusable on systems that don't support HFS.
At present, the systems that can read HFS CD-ROMS are Macs, Amigas (with AmiCDROM, available from ftp://ftp.cdrom.com/pub/aminet/disk/cdrom/), PCs running Linux or OS/2 (with appropriate patches), the Apple IIgs, and SGI machines running Irix (they appear as AppleDouble format).
Some authoring packages for the Mac and Windows allow the creation of "hybrid" CDs that have both an ISO-9660 filesystem and an HFS filesystem.
Apple has defined some ISO-9660 extensions that allow Macintosh files to exist with file and creator types on ISO-9660 CD-ROMs. A description of the extensions is available as tech note FL 36 from: http://developer.apple.com/technotes/fl/fl_36.html
Microsoft, being Microsoft, created their own standard called "Joliet". This is currently supported by Win95 and WinNT. It's useful when doing backups from Win95 onto a CD-R, because the disc is still readable as ISO-9660 but shows the long filenames under Win95.
The spec can be found at http://www.ms4music.com/devl/dvjoliet.htm.
Recent versions of Linux (kernel >= 2.0.34 and 2.1.60) have Joliet support. Older versions can be patched; for details, see http://www-plateau.cs.berkeley.edu/people/chaffee/joliet.html.
To patch Joliet support into OS/2, visit: http://service.software.ibm.com/os2ddpak/html/miscellb/os_2warp/updatedc/index.htm
Some Creative CD-ROM drivers have trouble with CD-ROMs that have Joliet filenames. You may need an updated copy of sbided95.exe, available from http://www.ctlsg.creaf.com/wwwnew/tech/ftp/ftp-cd.html.
Adaptec's Easy-CD Pro software allows creation of discs in "Romeo" format. This never really caught on.
These are new standards intended to replace ISO-9660. The UDF filesystem specification is based on ISO/IEC 13346 (which is closely related to ECMA-167). For more information about these standards, see the links in section (6-4).
Short answer: you don't, unless you have a CD-i add-on board. Even if you have a CD reader compatible with the CD-i (Green Book) standard, there are still a number of obstacles in your way. The filesystem used isn't ISO-9660, and CD-i players are based around a 680x0 CPU and have special hardware for video and audio.
Longer answer: it depends on what kind of disc it is, and what you mean by "use".
PhotoCD and VideoCD discs are CD-ROM/XA "Bridge Format" discs that play on CD-i players as well as dedicated players and computers. These use the ISO-9660 file system, and can be read with commonly available PhotoCD software and MPEG-1 players.
DigitalVideo discs from Philips manufactured before June, 1994 are in CD-i format, not VideoCD format. If your CD-ROM drive supports raw 2352-byte sector reads, it's possible to pull tracks off of a Green Book format disc, and extract audio or MPEG video data. VCD PowerPlayer from CyberLink (http://www.cyberlink.com.tw/) can play CD-i movies directly off of a Green Book disc.
Typical Red Book audio CDs don't have this information. Software audio CD players like those provided by Adaptec or Microsoft require you to type in the information, which is then stored in a database on your hard drive. The discs are identified by computing a signature based on track offsets and other fields. See http://www.cddb.com/ for a full explanation, as well as databases of CD info.
Some newer formats, like CD Extra, allow or even require such information to be included on the CD. See Sony's pages at http://www.cdextra.com/.
Some recent CD players are advertised as "CD-Text Ready". These use the CD-Text data embedded in the P-W subcode channels to display disc and track title data. See section (3-28) for more about CD-Text.
CD-R's have a pre-formed spiral track, and the sector addresses are hard-coded into CD-R media, so there's no flexibility. Every disc holds a predetermined amount of data.
Most discs hold slightly more than 74 minutes. How much more depends on the brand of media, batch of media, and perhaps even on the recorder used (see section (7-6) for more details on how much a CD-R can hold). In some situations you can exceed the stated capacity of the disc; see section (3-8-2) below.
Since CDs are written in a spiral, the amount of data you can get on a disc is affected by how tightly spaced the "groove" is. A standard Red Book audio CD or Yellow Book CD-ROM is designed to allow at most 74 minutes of data. By using a tighter track pitch on the spiral "groove" on the glass master, manufacturers can get more data onto the disc. In theory this could make it harder for some CD readers to use the discs.
There *are* 80-minute CD-R blanks, but they're very expensive, and may not work on all systems. Some sources say that the longest possible CD-R is 79 minutes, 59 seconds, 74 blocks long, because of the way that the last possible start time of the lead-out is encoded, but some recorders may allow even larger values. See the next sub-section for more about 80-minute media.
The easiest way to get more data onto a disc is not to try. For audio CDs, you can leave off one or two tracks that you're not overly fond of. For data CDs you may be able to drop some images or sample data. The most common problem people encounter with data CDs is trying to copy them as a collection of files rather than doing a bulk copy of the entire disc. See also section (3-24).
One user suggested using the "speed up" function of SoundForge or CoolEdit to increase the speed of extracted WAV files by 3%. This supposedly gives better results than resampling, and allows writing 77 minutes.
If you have a mono recording, you could double the length of a CD by recording half the sound on the left track and half on the right. However, the track markers apply to both tracks, so providing random access to specific sections can be tricky.
If you're trying to copy a CD-ROM or VideoCD and running out of room, you may have a different problem. See sections (3-24) and (4-25).
Here's a few personal notes on my experiments with TDK 80-minute "green" blanks. Such discs are supposedly available directly from TDK (USA sales +1 800 835 8273), and I was able to purchase a small quantity (three discs) from Microboards at http://www.microboards.com/.
The discs were part number SCWA-ETC80A-X, priced at US$40.00 per disc in October 1997. Yes, that's about 20x the cost for an extra 8% storage. The discs were unbranded. The only difference I could see between these and other TDK green discs is that on the hub it says "CD-Recordable 6129B-80". Easy CD Creator Deluxe v3 showed 359,624 blocks (702.8MB in MODE-1) on the TDK 80-minute blanks, versus 333,010 blocks (650.8MB) available on my Mitsui gold 74-minute blanks.
Relatively inexpensive 80-minute blanks are becoming more common. Examples of sites include http://www.cd-brennen.de/cdr/, http://www.transco.co.uk/, http://www.burlington-av.com/, http://www.web-access.net/~clarkent/, and http://www.esware.net/empire/hardware/cdrom/cd.htm.
The first challenge was finding software that would work correctly with the discs. Neither Easy-CD Pro 95 v1.2 nor Easy CD Creator Deluxe v3.0 would allow me to do a test recording with more than 650MB of files. I ended up using mkisofs to create an image file with 341,163 blocks (666.3MB) of data, composed of two large .AVI files, and three smaller pieces of one of the other .AVI files.
Using a Yamaha CDR-102 with v1.0 firmware, the first thing I tried was to burn the image file to a 74-minute blank. Easy-CD immediately rejected the disc, saying there wasn't enough space. I then put the 80-minute blank in and did a test run. Easy-CD Pro 95 had no problems burning the ISO image file, until the screen saver activated and McAfee anti-virus "screen scan" kicked in. Good thing it was a test burn; I got a buffer underrun. I killed the screen saver and virus checker and ran again, had a successful test run, and followed it with a successful burn.
To verify the data, I used Easy-CD Pro 95's "compare track" feature. This failed, complaining that one track was shorter than the other. My guess is that the compare feature has some sort of track length limitation. My next attempt was to use the Linux "sum" command to make sure that the disc was readable in my Plextor 8Plex. This worked fine, and the output of "sum" matched what I got on the 4x CD-ROM drive in the Sun workstation at work. I also tried the disc in a Mac 7500 and a Dell Pentium, and had no problems with either.
The next step was an 80-minute audio CD, and that's where things fell apart. Easy-CD Pro 95 v1.2 didn't work at all (!), Easy CD Creator Deluxe again refused to allow me to create a long audio CD, and with Jeff Arnold's software (both the DOS version and CDRWIN) the test write failed after a minute or so (after the lead-in had completed?). Strangely, removing the last two tracks from the cue sheet, which reduced it to 72 minutes, allowed the test write to succeed on both 74-minute and 80-minute blanks. It appears that the Yamaha CDR-102 drive is unwilling to write that much audio data.
Other people who have had experience with 80-minute CD-Rs have reported that compatibility with different CD-ROM drives was very good. However, bear in mind the following statement, which was sent by e-mail from a TDK representative:
"The CD-R80 is a special product developed by TDK to meet the application needs of software developers and music studios. To achieve its 80 minute recording time, track pitch and scanning velocity specification tolerances had to be minimized, reducing the margin of error between drive and media. This means limited compatibility between some CD-Recorders and CD-ROM Readers. If you intend to use this recording length, please check with your hardware manufacturer. Use of the CD-R80 is at one's own risk. No guarantees of performance are made by TDK."You may achieve broader compatibility using standard blanks and the over-burning "feature" described in the next section.
The capacity of a CD-R is calculated to allow enough space to hold at least 74 minutes of Red Book audio data and 90 seconds of digital silence. The silent area is called the "lead-out", and is included so that a CD player will realize that it has reached the end of the disc, especially when fast-forwarding.
When a recording program tells you the exact capacity of the disc, it's not including the area reserved for the lead-out. There's nothing magic about this reserved area though. With the right kind of setup -- and a willingness to accept write failures as a matter of course -- you can put data into the reserved area, and possibly into a few blocks past the end of it. This is often referred to as "overburning" a disc.
How much more you can fit depends almost entirely on the media. Some brands will hold as much as 78 minutes, but it varies from batch to batch. See http://cdr.mypage.org/ for a long list of "offical" capacities.
You also need the right recorder and the right software. The Teac CD-R55S, Plextor PX-R412C, Yamaha 4xx/4xxx, and Memorex/Dysan CRW-1622 units have been used to write "extra long" audio discs successfully. The recent Philips, HP, and Ricoh units don't seem to be willing to do so. Not sure about Panasonic. The firmware revision may be important.
To write such a disc, you need to use a program that won't refuse to exceed the disc capacity. For example, CDRWIN will warn you but allow you to continue, while other programs will simply refuse. Gather a large collection of audio tracks, and start writing. Eventually the recorder will attempt to write past the end of the disc, and the write process will fail. Now play the disc, preferrably in a player that shows the total elapsed time for the entire disc. When the music cuts off, make a note of the time. That's the absolute capacity of the disc.
Most (all?) CD players will display the total disc time when you first put the disc in. This value represents how much you tried to write, not how much was actually written. If you want to impress your friends, try to write 88 minutes of music. You won't get anywhere near that far, but the CD player will show it.
There isn't a reliable way to determine absolute "over capacity" without actually writing to the disc, but it's reasonable to assume that the capacity of one disc in a box of 10 is representative of the rest.
It should be possible to write a CD-ROM in the same manner as an audio CD, but the space would have to be calculated so that the write failure occurred when the lead-out was being written. Otherwise, some of the files that appeared to be on the disc wouldn't actually exist.
Recording in DAO mode may be helpful to ensure that the lead-in gets written. Without a table of contents, the disc is useless. It's very likely however that you will be able to finalize the disc even after the write fails.
Depending on the disc and your player, you may have trouble seeking out to tracks near the end of the disc. Also, your CD player may behave strangely when it walks off the end of the disc: one user said he had to open and close the player afterward to convince it that a disc was still loaded.
The disc surface past the end of the area reserved for the leadout may be unreliable. Attempting to use more than 90 seconds (about 15MB of MODE-1 data) beyond the rated capacity of a disc could be asking for trouble.
It's possible to perform similar tricks on 80-minute media. Experiments with TDK 80-minute discs resulted in a recorded length of 82:09. MMC recorders don't seem to like having the lead-out position any later than 88:29:74, but that shouldn't get in the way.
First off, you need to be aware that certain aspects of PhotoCD creation are proprietary to Kodak. Programs like Adaptec's Easy CD Creator will allow you to create CD-ROMs with PhotoCD image files, and you will be able to view the images with Mac or PC programs that understand the PhotoCD file format, but you won't be able to look at the disc with a PhotoCD player.
http://www.kodak.com/digitalImaging/aboutPhotoCD/aboutPCD.shtml has the glossy brochure information, with some Kodak contact information. The Build-It and Arrange-It software, which allow you to create "real" PhotoCDs, costs about US$450. Kodak apparently pulled the software from the market in December 1997, so it may be difficult to find.
http://www.shiresoft.com/ gives you step-by-step instructions and software for creating "real" PhotoCD discs with Kodak's software. The Build-It program will only write to Kodak CD recorders, but a translator available from this web site will allow it to work with GEAR or CDRWIN. Follow the Kodak links on that page.
Incidentally, if you're planning to convert your own pictures, you will need a way to get your images digitized in the first place. Digital cameras like the Apple QuickTake will work, as will video capture boards or frame grabbers.
There are some utilities that will convert images into PCD format, but they only support the uncompressed base resolutions. The higher resolutions are compressed with an algorithm proprietary to Kodak.
If it's just a disc full of data (like JPEG images), writing the disc in minimal ISO-9660 should work. You may have to master it without the file version number (e.g. ";1") at the end of the name.
If you need the format to be more flexible, perhaps with separate executables for Macs and PCs, you'll want to build a "hybrid" CD that has two sets of files on it. Adaptec's Toast for the Mac is widely recommended for this. See section (6) for other options.
As always, it depends.
MS-DOS lets you see the first data session. Usually. Win95 lets you see the last data session. Usally. Adaptec's Session Selector and Ahead's MultiMounter will let you choose which session you see.
Some CD creation software (e.g. Adaptec Easy-CD Writer) writes a complete table of contents in each session, some of which refers back to the files from the previous session, allowing a form of incremental backup. (This will work for ISO-9660 discs, but won't work for HFS. However, this is less painful than it seems because a properly-configured Macintosh will let you mount all the sessions as individual volumes.)
Adaptec's Easy-CD Pro will allow you to combine the contents of several previous sessions by creating a new session (use RCD's Load Contents option to read the file/directory info from more than one session, then write and close a new session with that directory structure).
Some of it depends on the SCSI or CD-ROM driver you have installed. It's unwise to expect somebody else's system to treat multisession discs the same way yours does.
The tricky part in doing this -- unless you have a stand-alone audio CD recorder -- is getting the audio transferred to your computer and modifying it to suit your tastes. The act of writing a sound file onto a CD is fairly trivial with most recorders and software. If you're considering the purchase of a computer-connected recorder for transferring tapes or LPs to CD, you should worry less about the recorder and more about the quality of the digitized audio. Few, if any, people will insist that recorder A produces better quality audio CD-Rs than recorder B, but everybody has an opinion about sound cards.
Start with http://homepages.nildram.co.uk/~abcomp/lp-cdr.htm, and read through http://www.octave.com/library/audiocd.html. These go into a lot more detail than this section does.
If you have questions or need a recommendation on a sound card, you might want to try:
news:rec.audio.techSome highly technical benchmark evaluations of cards are available at http://www.rockpark.com/soundcards/.
news:comp.sys.ibm.pc.soundcard.tech
To record on your PC, connect the output of the receiver/amplifier to the
"line in" on your sound card. If you want to go directly from a record
player, you need to run it through a pre-amp (which both pre-amplifies the
signal and equalizes it to RIAA standards). Anything labeled "preamp out"
or "tape out" can be connected directly.
You can use the A/D (analog-to-digital) converter built into a sound card like a SoundBlaster 16, but the sound quality will not be very good. The sound cards from Turtle Beach (Tropez, Tahiti) and CrystaLake are a step up, and a Digital Audio Labs CardD+ is about as good as it gets for internal A/D cards. If you're really serious, you should get an external A/D converter such as the Symetrix 620, and feed the digital output from that into the computer (another way of accomplishing the same thing is to record to an audio DAT tape and then use the digital output on the DAT recorder; see the next section for details).
A problem with some sound cards (really cheap Opti and ESS cards have been named) is that the crystal that controls the recording sample rate is off. If the card doesn't do the sampling at the correct rate, the recorded audio may end up slightly slower or faster than the original. This will become apparent when the sound is played back off of a CD or through a better sound card.
When recording, try to get as much signal as possible. Normalization will bring the signal level up, but can't replace parts of the signal that were lost. Sound editing utilities, such as GoldWave or Cool Edit, can be used to equalize, normalize, and even perform noise reduction on your recordings.
Adaptec's Easy CD Creator includes an application called "Spin Doctor" that performs most of the tasks needed to transfer LPs to CD. Depending on your needs, it may provide a simple solution for all your needs.
There are a variety of programs that can automatically remove pops, clicks, and hissing from digitized audio. Few automated tools can do as good a job cleaning up pops and other noise as an experienced person, however. If you want to perform the transfer by hand, the following method has been suggested for PC users:
Cool Edit can be found at http://www.syntrillium.com/. A similar product called "GoldWave" can be found at http://www.goldwave.com/. A fancy commercial product called Sound Forge is described on http://www.sfoundry.com/. Algorithmix, at http://www.algorithmix.com/, has a noise reduction program called SoundLaundry. DART and DART PRO are designed for audio restoration, and can be found at http://www.dartpro.com/. Another fancy (and expensive) program is at http://www.waves.com/. See also DCart at http://www.diamondcut.com/.
Don't forget that CD audio is 16-bit PCM stereo samples at 44.1KHz, and will chew up disk space at roughly 176K per second. Playing back large sound files is difficult with simple-minded applications like the standard Win95 WAV player, because they try to load the entire file into memory all at once. Cool Edit 96 is able to play files back as it reads them, and works very well even over a network. (Section (4-20) has some other suggestions on this same topic.)
See section (3-3) for some tips on avoiding clicks when committing the audio to CD.
You can find odd bits of hardware that will play or enhance playback of older recording formats (78's, LP's, 16" Radio Transcriptions) at Nauck's Vintage Records (http://www.78rpm.com/).
For those of you wondering what the deal with pre-whatever is, this little tidbit is courtesy Mike Richter:
"Preemphasis has been used since the earliest days of commercial recording. In general, the high-frequency content of the music (or whatever) being recorded is low and the noise is high. Therefore, treble was boosted and lows were cut by a preemphasis curve which was removed in playback. The standard RIAA curve for turnover and rolloff (the amount and frequency for treble and bass, respectively) was not accepted universally until the 50's, and some fine preamps offered selectable values with presets for the common curves into the early transistor era."
Buy a card that will allow you to go from DAT to hard disk digitally. Make sure you get one that can handle the same digital standard the DAT recorder uses, i.e. S/PDIF (Sony/Phillips Digital Interface Format, sometimes referred to as "domestic") or AES/EBU ("professional").
Some of the solutions for the PC are the DigiDesign AudioMedia (see http://www.digidesign.com/), the Zefiro Acoustics ZA2 (see http://www.zefiro.com/), the AdB Digital Multiwav Pro (see http://www.adbdigital.com/), the Digital Audio Labs CardD+ (see http://www.digitalaudio.com/products.htm), or the Turtle Beach Fiji (see http://www.tbeach.com/products/fiji.htm). The CardD+ comes highly recommended. There may be newer versions of these products, so be sure to check out the web sites.
Visit http://www.digitalexperience.com/cards.html for a feature comparison of many different models.
A cheap S/PDIF card available from Computer Geeks (http://www.compgeeks.com/) was evaluated by some newsgroup readers. Apparently there were some problems with the physical dimensions of the c