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3-8-3] How can I exceed the stated disc capacity ("overburning")?




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This article is from the CD-Recordable FAQ, by Andy McFadden (fadden@fadden.com) with numerous contributions by others.

3-8-3] How can I exceed the stated disc capacity ("overburning")?

(1999/10/10)

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.
You can use Feurio! (section (6-1-42)) to compute the maximum size of a
specific disc without actually writing anything on it.

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 Philips
36xx, HP 71xx, and Ricoh 62xx units don't seem to be willing to do so. In
some cases, getting the firmware revision may be important. A recorder
that isn't able to do this sort of writing will usually reject the cue
sheet before writing begins.

To write such a disc, you need to use a program that won't refuse to exceed
the disc capacity. Easy CD Creator, in an attempt to prevent you from
making mistakes, will refuse to allow you to write more than you should be
able to. CDRWIN will warn you that the write may fail, but will allow you
to continue anyway. Nero has a preference (under Expert Features) called
"enable oversize disc" that allows the longer write.

One approach to determining the maximum disc length is to 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
on 74-minute media, but the CD player will show it.

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.

Further commentary and instructions can be found at
http://www.cdmediaworld.com/ under "OverSize / OverBurn CD-Rs", including
a list of recorders that are known to work and step-by-step instructions
for using popular software.


 

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