CD Facts

We get a lot of phone calls about CDR Media and the Duplication process. Here are a few of the most common questions:

1. What is CD-Recordable?
CD-Recordable (or CD-R) stands for Compact Disc Recordable. It is a technology through which a blank compact disc, a CD-R, is converted into an audio CD or a conventional CD-ROM. The finished "burned" CD is capable of being read in any CD drive of a computer, or a stand alone CD player (for audio).

2. What is the recording speed of CD-R?

The "speed" measurement of a CD recorder is how fast it can record data to blank CD-R media. Speed designators such as "2x", "4x", and "8x"are multiples of the original playback speeds of first generation CD-ROM players. For a CD-ROM player or CD recorder, a "1x" speed translates to 153,600 bytes per second. This is usually rounded down to 150 kb per second.

4. Is it necessary to verify discs after recording?

Periodic verification of your recordings helps you maintain an appropriate quality level. If you never verify the data, then sooner or later you will have a problem. An absolute zero defect disc is not possible. All discs have errors. The normal reading process corrects these errors by means of hardware decoders that have error recovery algorithms in them as well as the additional third level of error correction contained in a CD-ROM/CD-R data stream that corrects faulty data through software. You should verify the data and learn how to use a CD quality analysis tool to determine that the quality of the recording is within the specification limits for errors.

5. I can read the CD-R disc on my CD-R drive, but when I put it into a CD-ROM drive it won't play. What should I check?

The most common reason for this is that the disc has not been "finalized" by the recording software making it unreadable by the CD-ROM reader. The finalization process is the last part of the multisession recording process which writes the overall disc table of contents into the disc lead-in area which makes the disc conform to the ISO 9660 standard, or UDF protocol, required by most reader and reader driver software.


DVD Facts
1. Can I copy entertainment titles on DVD? Someone said there's software out there to get around the encryption.

No. Most DVDs are copy protected in one way or another, mainly by CSS encryption or Macrovision. Even if you could get around this, a pressed DVD can hold up to around 20 GB of data and video. Your DVD-R only holds 4.7 GB. And you'd have to re-author the video anyway. Do the industry a favor, and pay for your titles; if you like it enough to own it, show your appreciation to the people who put their time and effort into creating it.

2. What is DVD-RAM? Can I use it like a regular DVD?

DVD-RAM is almost entirely unrelated to DVD and DVD-R. It is a sectored media (like a hard drive) and is designed for write-multiple usage. It is not playable in most consumer DVD players. Its purpose is not usually video-type applications.

3. What is the difference between DVD+R and DVD-R?

The DVD+ standards (both DVD+R and DVD+RW) used to have faster writing speeds, and at 2.4x, this amounts to 3,324 KB/s. However, the new Pioneer A05 drive now adds 4x burning for DVD-R and 2x burning for DVD-RW (2x burning is equivalent to 18x CD burning). To put it into perspective, 2x writing, or 2,770 KB/s will mean that for writing to a full 4.7 GB DVD, a 2.4x drive will be some 5 minutes faster than a 2x drive. Burning a full 4.7 GB DVD will take around 25 minutes for a 2.4x drive. A 4x drive will burn the full 4.7 GB in about 15 minutes. Note that a 4x DVD+R drive will be released in Q1 2003.

Raw burning speed is not the only factor when it comes to performance though. DVD+RW design ensures shorter lead-in and lead-out times - this will mean it takes shorter to finalise than DVD-RW media. Formatting for DVD-RM or DVD+RW media can be done on-the-fly, although some older software for DVD-RW may not support this feature.


CLV and CAV Burning :
There are also two different recording methods, CLV (Constant Linear Velocity) and CAV (Constant Angular Velocity). CLV is mainly used in streaming video applications where high transfer speed is required. CAV has better random access times, and hence better for computer storage/applications.

DVD-R/RW uses CLV, which makes them good for DVD-Video applications. DVD+R/RW can use both CLV and CAV.

DVD-R and DVD-RW
DVD-R/W was the first DVD recording format released that was compatible with standalone DVD Players.
DVD-R is a non-rewriteable format and it is compatible with about 89% of all DVD Players and DVD-ROMs.
DVD-RW is a rewriteable format and it is compatible with about 72% of all DVD Players and DVD-ROMs.
DVD-R/W supports single side 4.7 GB* DVDs(called DVD-5) and double side 9.4 GB* DVDs(called DVD-10).
These formats are supported by DVDForum.

DVD+R and DVD+RW
DVD+R/W has some better features than DVD-R/W such as lossless linking and both CAV and CLV writing.
DVD+R is a non-rewritable format and it is compatible with about 83% of all DVD Players and DVD-ROMs.
DVD+RW is a rewritable format and is compatible with about 72% of all DVD Players and DVD-ROMs.
DVD+R/W supports single side 4.7 GB* DVDs(called DVD-5) and double side 9.4 GB* DVDs(called DVD-10).
These formats are supported by the DVD+RW Alliance.