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Archive-name: cdrom/cd-recordable/part3
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Last-modified: 2004/04/15
Version: 2.53

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Subject: [4] Problems
(2000/06/05)

Problems that arise when burning a CD-R.

Some suggestions that fix most common problems:

 - RTFM (Read The Fine Manual).  Sometimes it's *supposed* to work that
   way.  If you didn't receive a manual with the product, it may be in
   text or Acrobat form on a CD-ROM.
 - Check your software version.  You may need a newer version of the
   software for correct operation with your hardware (yes, even if you
   received the software with the recorder).  Most, if not all,
   CD recorder software publishers have web sites with updates.
 - Update the software.  Even if the software is new enough to be
   compatible, there's some chance that your bug has already been fixed.
 - Under Windows, check your ASPI layer.  See section (4-44) for URLs
   and notes.
 - If you've tweaked your PC BIOS to the limit and are overclocking
   everything, reset it to defaults and see if your problems clear up.
   You can always tweak it back.  If you're using a motherboard with
   a VIA chipset, make sure you are running the absolute latest version
   of the VIA drivers.
 - Some problems with PC ATAPI drives go away when DMA is turned off for
   the drive (via the Win9x device manager; see section (5-15-1)).  You
   might also need to uninstall incompatible bus-mastering drivers
   (section (5-15)).
 - Under Windows, rename \Windows\System\Iosubsys\scsi1hlp.vxd to
   something that prevents it from being loaded ("scsi1hlp.vx_").  See
   if your problems get better.  scsi1hlp.vxd is only required for
   compatibility with old SCSI devices.
 - If you have an older recorder, and it seems to be getting progressively
   worse over time, it may need to be cleaned.  See section (3-30).


Subject: [4-1] What does "buffer underrun" mean?
(2002/11/15)

It means you have an attractive new coaster for your table.

Generally speaking, the CD recording process can't be interrupted in
mid-session.  Once the laser starts writing, any interruption would create
a physical gap on the disc that could confuse CD readers.  The recorder
must always have data to write, from the moment the recording starts until
the session ends.  To avoid a situation where a temporary slowdown in the
computer causes the write process to fail, the makers of CD recorders
put a write buffer in the drive, usually between 512K and 4MB in size.
Data read from the hard drive, tape, or another CD is stored in the buffer,
and pulled out as needed by the recorder.

If the recorder requests data from the write buffer, but there's none there,
it's called a buffer underrun.  The disc is still spinning, but there's no
data to write, so the recording process aborts.

This was a very common and very annoying problem for many years, so
most recorders released in 2001 or later have optional "buffer underrun
protection" features available.  See section (2-31).

You can sometimes use a disc that failed during writing by closing the
session and starting another, assuming there's enough space left on the
CD, and assuming your pre-mastering software didn't choose to finalize the
disc for you.  If you were using disc-at-once recording, you're probably
out of luck.

Advice for preventing buffer underruns is scattered throughout this FAQ.
A brief summary:

 - If your hardware and software support it, enable buffer underrun
   protection.  Usually this is just a checkbox.
 - Use a fast, AV-friendly hard drive (i.e. one that doesn't do slow
   thermal recalibrations).  Pretty much all drives sold since the
   late 1990s fall into this category.
 - Record at a slow speed - it takes longer to empty the buffer when
   recording at 1x.
 - Don't do anything else with the computer while recording.  Don't record
   from a file server.
 - Defragment your HD, especially if you're doing on-the-fly recording.
   (But don't defragment *while* you're recording.)
 - Record from a disc image file rather than on-the-fly.
 - Depending on your setup, putting the recorder and your hard drive on
   separate SCSI or IDE controllers may be helpful.
 - Keep your CD-R cool.  Sometimes the drives fail when they overheat,
   with a buffer underrun or an inability to finalize a session.  This
   is rarely a problem with drives made in 2000 or beyond.

Also watch out for things like anti-virus programs that wake up, virtual
memory settings that cause swapping, screen savers that activate during the
CD creation process, unusual network activity, and background downloads of
data or faxes.  One way to check is to run the HD defragmenter in Win9X.
If it restarts every few seconds, it's because something is hitting the
drive.

Some game discs use a form of copy protection where bad sectors are
deliberately placed on the original CD.  Attempting to copy one of these
discs on the fly may fail, because some CD-ROM drives slow down and
repeatedly try to read the "damaged" blocks.  The slowdown may result in
a buffer underrun before the CD-ROM drive reports an error.

A utility included with Microsoft Office, called "FindFast", will
occasionally start up and scan your hard drives.  Disabling this by
deleting the shortcut in the Windows\Start Menu\Programs\StartUp folder may
be necessary.

If you're using Windows, see the sub-sections on Auto-Insert Notification
and VCACHE settings, below.


http://www.roxio.com/en/support/cdr/bufunder.html has a comprehensive
collection of buffer underrun info.

http://www.adaptec.com/support/configuration/cdrec.html is interesting
reading for users with CD-Rs attached to Adaptec SCSI cards.  They're
pretty far on the conservative side, but if you're having trouble this may
help you.

An article by Dana Parker entitled "CD-R on the Safe Side: Seven Rules of
Successful CD Recording" in the April 1997 issue of Emedia Professional
listed the Seven Habits of Successful CD-R Users:

 1. Defragment Your Disk
 2. Use a Partition for Staging Input
 3. Create a Real Image
 4. Test before writing
 5. Stabilize Your System for CD-R
 6. Shut Down Other Applications
 7. After the Burn: Label and Test

If you really want to be careful, you can shut down background stuff under
Win95/98 with WinSolo from http://www.procode.com.au/winsolo/ (the web site
was down at last update, but a search for it on http://www.google.com/
turned up a number of shareware sites that have it).  Another option is
WinTasks from http://www.liutilities.com/products/wintasksstd/; see
http://www.liutilities.com/products/wintasksstd/tutorials/tutorial1/ for
a tutorial.

(Side note for search engines: some versions of Ahead's Nero refer to
buffer underruns as "loss of streaming".)


Subject: [4-1-1] What's the deal with Windows Auto-Insert Notification (AIN)?
(1999/09/12)

Some of the Windows-based recording software recommend turning off
Auto-Insert Notification.  Having this on can interfere with closing
sessions or even just inserting discs into the drive.  Most of the recent
software will disable it automatically, but some of the older products
require you to disable it manually.  You can do so under Win95/Win98 by
opening the "System" icon in the Control Panel, and selecting "Device
Manager".  For each item under CD-ROM, select the device, click on the
"Settings" tab, and make sure the "Auto Insert Notification" checkbox is
unchecked.  [With a vanilla Win95 setup I got SCSI errors when AIN was off
for my CD-R but on for my CD-ROM, even if the CD-ROM drive wasn't in use at
the time.]

If you're using WinNT, you can turn it off with the "TweakUI" program
available in PowerToys (available from the Microsoft web site at
http://www.microsoft.com/), or by modifying a registry key with Regedit32
(0=disabled, 1=enabled):

  HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ Cdrom \ Autorun

If your software automatically turns AIN off, and you can't figure out how
to turn it back on, the TweakUI program may be able to help.  Check the
"Paranoia" settings.  (Incidentally, if installing the Power Toys screws up
your icons, select "Rebuild Icons" from the "Repair" menu.)  If you turn it
off and on again, You may have to reboot in some configurations before it
will work again.

Sidebar: the trouble with Auto Insert Notification is that it periodically
attempts to find a valid disc in the CD recorder.  A blank disc isn't very
interesting to Windows, so nothing happens.  When the table of contents is
written to the disc, it suddenly becomes interesting; and if Autorun or
Autoplay are enabled, enough activity is generated by Windows' attempts to
read the disc that the write fails.

Because it only affects CDs with actual data being written to them, a test
write won't end in failure.  It can be very frustrating to have 100%
success with test writes and 100% failures with actual writes!  With
disc-at-once recording, the process will abort very near the start of
recording, probably leaving an empty but useless disc.  With track-at-once
recording, it will fail at the end, and you may still be able to finalize
the disc.  Audio CDs will most likely work fine even if interrupted at the
end of the write process.

IMPORTANT: if you are using DirectCD for Windows, you must have AIN turned
*on*, or some things won't work quite right.  The most obvious failure mode
is that long filenames aren't shown, but some reports indicate that data on
the disc can get trashed as well.  This can make life interesting if you're
also using a conventional writing application, unless the application is
good about turning AIN off before writing.  The other Windows applications
currently sold by Roxio (notably Easy CD Creator) will automatically
disable Auto-Insert Notification when appropriate and re-enable it
afterward, so you don't have to worry about AIN at all.


Subject: [4-1-2] What's all this about Win9x VCACHE settings?
(2001/07/09)

One problem with Win95 is that by default the size of the file cache is
unrestricted.  This means that all available memory will eventually get
filled up with file data, which will cause the virtual memory system to
start swapping out pages from executing applications.  When something needs
to be executed from a page that has been swapped out, it takes time to pull
it back in off the disk.  While this is happening, the CD recorder's buffer
could drain completely.

The procedure is simple:

 (1) Open the file SYSTEM.INI with a text editor.  This file is usually
     C:\WINDOWS\SYSTEM.INI.
 (2) Find the section labeled "[vcache]".
 (3) Add the following lines *after* the "[vcache]" line:
        MinFileCache = 16384
        MaxFileCache = 16384
 (4) Save the changes to the file, and reboot.

The above values are recommended for a system with at least 64MB of RAM.
A common rule of thumb is to set "maxfilecache" to 25% of your RAM, up
to a maximum setting of 16MB.  Because of (actual or perceived) bugs in
Win95, some people recommend setting "minfilecache" and "maxfilecache" to
the same value.

If you have an older system with only about 16MB of RAM, you might want
to use instead:

  MinFileCache  = 512
  MaxFileCache = 4096

The [vcache] change has reportedly cured severe buffer underrun problems
with some versions of CDRWIN and removed popping noises during digital
audio extraction with Easy CD Creator.  It's a good thing to do to any PC
running Win95.  It's not necessary for WinNT.  It's not clear whether this
will help with Win98, but it doesn't seem to hurt.

If you are uncomfortable tweaking your SYSTEM.INI file, try CacheMan at
http://www.outertech.com/.  It allows you to modify the above settings,
and a few more besides.


Subject: [4-2] I can't get long Win95 filenames to work right
(1998/04/06)

Typical symptoms can be described like this:

 - Works fine in Win95 Explorer
 - Under DOS the directories are visible, but instead of "dirname1"
   you get "dirname57".  Attempting to read them results in errors.
 - Typing 'cd dirname~102' may fail while 'cd "Long File Names without the ~"'
   will work.

The problem occurs when certain CD-R writing programs are used to create
the discs.  The short and long forms of the filenames are sorted
differently, so some of the files can't be found.  Using newer software
(e.g. Easy CD Creator 3 instead of Easy-CD Pro) should produce better
results.


Subject: [4-3] I can't read the multisession CD I just made
(1998/04/06)

The SCSI driver needs to believe that the CD-ROM drive can handle
multisession discs.  Most likely you will need to update your SCSI drivers
before this will work.

(This problem was reported with an HP4020i and a Buslogic BT946C controller;
if you have an HP drive you should get the c4324hlp.vxd driver from the HP
web site.  See section 6 for the address.)

One possible cause of this problem is writing a multisession disc in MODE-1
format.  Some older CD-ROM drives incorrectly assume that a MODE-1 disc
can't be multisession, so they don't look for additional sessions unless
it's written in MODE-2 (CD-ROM/XA) format.

Also, if the final session on the CD isn't closed, standard CD players may
become confused (the NEC 6Xi certainly does under Win95).  This doesn't
mean that the *disc* must be closed, just that the *session* must be
closed.  (Actually, the NEC 6Xi doesn't like open discs either... sigh.)

A note on one of the Ricoh pages indicates that the Ricoh 1420C is unable
to read sessions smaller than 3 minutes (about 26MB) until firmware 1.6x.


Subject: [4-4] Write process keeps failing N minutes in
(1998/04/06)

There's a couple of possibilities.  One is that your data source can't keep
up with the CD-R; try using disc-at-once writing from a disc image with the
speed set to 1x.  If it seems to be getting worse over time, you may just
need to defragment your hard drive.

If that fails, a number of people have discovered that the problem is a
faulty CD-R unit (similar behavior has been reported on Sony and HP units,
which have different mechanisms).  You should try 1x writing from a fast
source and with different sets of data before contacting the manufacturer,
since they will likely tell you to do exactly that anyway.

Be sure that there aren't environmental factors creating difficulties.
CD-R units are usually built to handle small shocks, but having a set of
speakers playing loud music on the same table as a CD-R may cause it to
skip, resulting in a failed write.  Sonic booms, heavy construction
equipment, and nuclear detonations may have similar effects.

It's also possible that you simply have a bad batch of media.  Try a
different type and brand of disc.  Some distributors (e.g. dataDisc) will
exchange media that's provably defective.

Be careful with Advanced Power Management functions on some PCs.  If the
keyboard and IDE devices are completely idle, the system may decide that
nothing is going on and switch to a low-power mode.  Ditto for screen
savers that kick in after the system has been idle for a certain period.


Subject: [4-5] Why did my CD-R eject between the "test" and "write" passes?
(1998/04/06)

Most CD recorders need to clear their memory between the "test" pass and
the "write" pass.  For some recorders, the only command that does this is
"eject".  If the recorder has a tray it just goes out and back in, but if
it uses a caddy manual intervention is needed.

Some CD-R packages allow you to start the real write pass a few seconds
after the test pass has succeeded.  They may not disable this even though
they know that the disc will have to be ejected.  Make sure the option is
set to "wait until told to continue."


Subject: [4-6] My CD-ROM drive doesn't like *any* CD-R discs
(1998/04/06)

A very simple test is to take a CD that DOES work, copy it, and try both
(this ensures that your problems aren't being caused by, for example, a
drive that doesn't support multisession CDs).

Sometimes the firmware can be at issue.  In one specific case, a Goldstar
GCD580B CD-ROM drive was able to read CD-Rs under Win95 but not MS-DOS
6.22.  Upgrading the firmware from v1.01 to v1.24 solved the problem.

If it fails with different kinds of media, the CD-ROM drive either doesn't
like discs written with your recorder, or doesn't like CD-R media at all.
In one case, returning the CD-ROM for an identical unit resolved the
problems.

While there are stringent specifications for discs, there are no such
specifications for CD players and CD-ROM drives.  They just have to play
the discs.  If the disc and the drive are both marginal, you lose.


Subject: [4-7] How do I avoid having a ";1" on my ISO-9660 discs?
(1998/04/06)

The ISO-9660 standard says the version number (a semicolon followed by a
number at the end of every filename) has to be there.  Most operating
systems simply ignore it, but until recently the Mac didn't, causing some
problems.

(For the Mac, look at "ISO 9660 File Access" in the System:Extensions
folder with Command-I.  If the version shown is 5.0 or greater, your system
should handle the version numbers just fine.  If not, you should update
your system software.)

If you can't find a way to work around it, "mkisofs" has an option to omit
the version number when constructing an ISO-9660 image.


Subject: [4-8] I keep getting SCSI timeout errors
(1998/04/06)

http://www.adaptec.com/support/configuration/cdrec.html has some advice on
SCSI configuration.  Basically, check your cabling and termination (see
section (4-17) for more advice there), turn off features you don't need,
and make sure Auto Insert Notification is off (see section (4-1-1)).


Subject: [4-9] I'm having trouble writing a complete disc
(2002/08/16)

(This is for failures other than buffer underruns.  For those, see
section (4-1) and perhaps section (4-4).)

If it's failing right as the disc is being finalized, and you're recording
in track-at-once mode, try recording in disc-at-once mode instead.  It has
been suggested that some recorder+media combinations have trouble reading
the PMA (Program Memory Area, where a copy of the TOC is kept until the
disc is finalized) at the end of a write.  With disc-at-once mode the
TOC is written early, so it doesn't have to get read out of the PMA.
See section (2-19) for the low-down on disc finalization.

When in doubt, check your ASPI layer.  See section (4-44).

One user with an ATAPI recorder found that disabling DMA (from the Win98
peripheral properties) made things better.

Try letting the drive cool down (leave the machine off for a couple of
hours if you have an internal drive).  Power up the machine and
immediately record the disc.  Sometimes heat buildup can cause problems,
though this is less common with recent drives.


This was happening frequently with the HP4020i running off an AdvanSys SCSI
card under Win311 (i.e. WfWG).  The solution here was to remove IFSHLP.SYS
from the CONFIG.SYS.  (IFSHLP.SYS is somehow involved with 32-bit file
access and network support, so you may have to disable both of these before
disabling IFSHLP.  You may have better luck under Win95.)

Another user with the same setup found that doing power-up diagnostics and
device reset right before burning the CD helped.


Subject: [4-10] What's the CDD2000 Write Append Error / spring problem?
(2000/08/08)

This seems to happen on Philips CDD2000-based units, such as the HP4020i,
usually a short while after the warranty runs out.  The most common cause
is a spring that weakens with age, but it might also be due to lubrication
breakdown.  After a while, the recorder starts failing when trying to write
beyond a certain point on the disc.

The ways of dealing with this range from minor system changes to the
placement of chicken entrails on selected components.  Reducing the DMA
rate on the AdvanSys SCSI card (for the HP4020i) may help, buying better
SCSI cables and checking for proper termination may make a difference, or
even powering off and on again right before the burn.  For some users,
however, the problem is mechanical rather than spiritual.

One user was told by Philips tech support that if error 50h (write append)
occurs, it means the drive has to be returned to the repair center.  Other
users have been told that the error can occur when attempting to write an
empty directory or zero-length file.  Under Easy-CD Pro '95, this is
reported as error 171-00-50-00 (see the Roxio web site for a complete
list of error codes).

If the fault is caused by the worn spring, it may be possible to fix the
problem by replacing the spring.  This will definitely void your warranty,
and you shouldn't even think about trying this unless the only alternative
is to throw the drive away.  Jonathan Oei posted some details about the
process (search for comp.publish.cdrom.hardware, subject "CDD2000 & Spring
Fix", on http://newsone.net/), and a detailed description of the
procedure can be found on http://www.fadden.com/doc/fix-hp4020i.txt.

This procedure requires some special tools (mini torx drivers and really
fine jeweller's pliers), and involves disassembling much of the drive.  If
you open up the drive and remove the circuit boards, you will see that the
laser writing assembly is moved by a DC stepper motor.  The motor has a
plastic drive gear that is meshed with a plastic "rack" on the laser.  The
spring in question is a piece of wire that pushes the rack against the
drive gear, so when it weakens the gear slips and the write fails.
Replacing the 0.012" wire with a 0.02" diameter wire solves the problem.

The high temperature in the drive may contribute to the breakdown of the
lubricants that allow the laser head to travel.  You may be able to prevent
the situation by installing a fan.

This question is also covered in the HP4020i FAQ, available at
http://www.cd-info.com/CDIC/Technology/CD-R/HP-FAQ.html.


Subject: [4-11] Getting errors reading the first (data) track on mixed-mode CD
(1998/08/16)

There's a 150-sector postgap at the end of the data track.  Most programs
deal with this automatically, some older ones don't.  If you're getting
errors, try subtracting 150 from the total number of sectors to read for
that track.


Subject: [4-12] My recorder ejects blank discs immediately
(2002/05/02)

There are a few of possibilities, some software and some hardware.

It may be that the system is looking at the disc, not finding a TOC (table
of contents), and ejecting it as useless.  One way to tell the difference
between the operating system rejecting the CD and the drive rejecting the
CD is to unplug the SCSI or IDE cable from the back of the CD recorder
before inserting the disc.

If the drive pauses for a little while before ejecting, it may be rejecting
the media.  On some units you get a blinking warning light instead.  If
this is happening, try a different brand of media.

If the problem is the operating system, you probably need to disable
certain features.  Under Win95, disable auto insertion for all CD-ROM
devices (see section (4-1)).  One user found that reinstalling Win95
helped.  On the Mac, you may just need more recent drivers.  On a Solaris
system, remove the recorder (probably the "cdrom" entry) from
/etc/vold.conf.

If that doesn't work, make sure the CD-R drive is perfectly level.
Apparently some older (1996-ish) units were sensitive to being tilted at
an angle.  Some users have had trouble when a CD-R has been on for a while
and has overheated, so if you only have trouble when the machine has been
powered on for a while, try putting a small fan above the unit to blow
air over it.

With some drives, improper SCSI termination can cause this behavior.

For the Yamaha CDR-200/CDR-400, this may be a sign that the drive has
broken down and needs to be replaced.  See section (5-1-1).

If nothing helps, there's a strong possibility that the drive is mis-
aligned and needs to be serviced.  This has been known to happen to drives
during shipping.

One user with a caddy-based drive reported problems when using the wrong
type of caddy.  It has to be a Sony-type caddy, which is the kind most
commonly found in stores.


Subject: [4-13] I'm getting complaints about power calibration
(2002/12/29)

The optical power output range of the laser in a low-speed CD-R is between
4 and 8 milliwatts.  (By comparison, the read laser runs at about 0.5mW.)
High-speed recorders and CD-RW devices use a greater range, up to about
40mW for 48X CD-R.  At the top end of the scale are DVD-R recorders,
which output around 100mW for 4x recording and 200mW for 16X recording.
CD-R and CD-RW discs have a section outside the standard recording area
called the Power Calibration Area (PCA) that is used to adjust the laser
for the brand of media you're using and the speed at which you're recording.

Power calibration errors indicate that the drive is having trouble
calibrating the power setting.  The most common cause is incompatibility
with the media you're using -- if you just switched to a new brand or
batch of media, this is a likely culprit -- but it can also be caused by
a dirty lens or a dying recorder.

If you're seeing "power calibration area full", it means the recorder
ran out of space in the PCA area.  There are 99 regions in the PCA area.
After 99 attempts to calibrate the power level, there won't be any
places left, and the recorder will report an error.

Try a few different kinds of media to see if the problem is an
incompatibility between your recorder and the discs you're using.  If that
doesn't make a difference, there are a couple of things you can do to
mitigate the problem.  First, you can try recording at a slower speed.
The recorder will use a different "write strategy", which usually means a
lower power level.  Second, if you're storing the discs in a cold place,
you may want to try heating them up to slightly above room temperature
(placing them near a heating vent works).  One user found that this helped.

If all else fails, and the drive is still in warranty, you should have
the drive checked by a repair facility.  If it's out of warranty, or
there's no easy way to have it checked out, you can try cleaning it.
See section (3-30).

Some versions of the firmware for the Philips CDD2000 (and HP 4020i) will
report a power calibration error if you try to do a 1x write after a 4x
read.

It's also good to verify, if your CD recorder is an internal unit, that
your power supply has enough capacity to run everything.  Recent PCs
systems should have a 300W or better power supply.

One user found that his problems went away when he created an image file
with Easy CD Creator, quit out of the program, restarted it, and then
recorded from the image at a moderate speed.  (Doesn't make much sense,
but if it works, use it.)


Subject: [4-14] My Adaptec 2940 pauses after finding my recorder
(1998/04/06)

This was observed with a Yamaha CDR-100.  The solution is to go into the
Adaptec BIOS (hit Ctrl-A during boot), and disable the "support removable
disks under BIOS as fixed disks" option and the "boot from CD-ROM" option.


Subject: [4-15] I can't see all the files on the CD-R
(1998/04/06)

There's a couple of possibilities: either they aren't there, or they're
there but you can't see them.  Looking at the disc from different machines
(e.g. Mac and PC) should give you some idea.

Out-of-date versions of MSCDEX have been known to "forget" certain files
when browsing a disc.  If you're using DOS or are using the "real mode"
drivers from within Win95, make sure you're using the most recent version
of MSCDEX.

Old versions of certain CD creation programs would occasionally omit things
when asked to burn a large number of files.  These problems haven't been
reported for some time, however.

If you were burning a multi-session CD, read the next section.


Subject: [4-16] My multi-session disc only has data from the last session
(1998/06/14)

A common mistake when burning a multisession CD is to forget to link the
files from the previous session into the current one.  This results in a CD
where you can see the new files but none of the old, unless you have a
program that lets you choose which session you look at.

If you're using Easy-CD Pro for Win31, CD Creator, or Roxio Easy CD Creator
v3+, you can load the contents of all the previous sessions, and burn a
new session that has all the files you want.  This feature wasn't available
in Easy-CD Pro 95, which only allows you to link to one previous session.

The files themselves aren't really lost.  Most recording software will
allow you to extract a track as an ISO-9660 image, and you can use WinImage
(section (6-2-2)) to pull individual files out of it.  If all else fails,
CD-R Diagnostic (section (6-2-6)) claims to be able to recover data from
"lost" sessions.

One caution: without something like Roxio's Session Selector, you may not
see the last session on the disc anyway.  Some CD-ROM drives stop looking
for sessions after a certain point.


Subject: [4-17] I'm getting SCSI errors
(1998/07/26)

Good SCSI cables and correct termination are absolutely essential.  SCSI
bus errors can cause buffer underruns or corrupted data (especially since
some vendors ship drives with parity checking disabled).

Bertel Schmitt wrote an excellent article on the ins and outs of proper
cabling and termination.  The article can be found in text form at
http://www.fadden.com/doc/scsi-trm.txt.  Granite Digital, a company
that makes high-quality cables and terminators, can be found at
http://www.scsipro.com/.

If you're using an HP 4020i with the AdvanSys SCSI card, reducing the DMA
transfer rate may help.


Subject: [4-18] Why doesn't the copy of an audio CD sound the same?
(1998/04/06)

There are actually two questions here, so I've split them into separate
sections.  The most common problem is that the audio extracted to the hard
drive doesn't quite match the original.


Subject: [4-18-1] Why doesn't the audio data on the copy match the original?
(1998/04/06)

Most problems are due to poor digital audio extraction from the source
media.  Some CD-ROM drives will return slightly different data every time
an audio track is read.  Others, like the Plextor line (e.g. 4Plex, 8Plex,
and 12Plex, but not 6Plex) will return the same data every time so long as
the source media is clean.

The most fundamental problem is that, if the CD is dirty, the error
correction may not be able to correct all of the errors.  Some drives will
interpolate the missing samples, some won't.

Another problem some CD-ROM drives face is "jitter".  See section (2-15)
for details.

See also section (3-3) on avoiding clicks in extracted audio, and section
(5-5) on which CD-ROM drives are recommended.


Subject: [4-18-2] The audio data matches exactly, why do they sound different?
(2002/12/11)

Suppose you extract the audio track from the copy, and it's an exact binary

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