I'm gonna have to write you a ticket - CD/DVD Speed

[AndreL]

I've been doing some reading on CD-ROM read speed. I've seen it up to 54x but most products out today at 52x. I myself have a 52x and it works great. I've been wondering why the speed doesn't go any higher, is it somethning about mis-reading. Could you show me some backup material on this like a web page.

Next is DVD, I've read DVD speed is double that of CD speed meaning; a DVD-ROM dirve at 16x is equal or almost eqaul to 40x on a CD. I've also read somthing about speed rotation, which for CD it is 52-54x and DVD 16-20x. What is that "Speed Rotation". I also pulled this off the post:
1x DVD = 1350 kb/.sec
1x CD = 150 kb/sec

One more thing how does layring fit in to this senerio with DVD. Does DVD speed increase its speed with multipule lyared discs. BenQ and Philips have a multilayered DVD RW that writes at 16x. Is that it with DVD 16x or will ther be faster speeds like 24 and 32 and go all the way up or past CD speed.

Just been wondering about this for some time now.

 

[high]

apparently, just like 16x dvds, thats the fastest the media can spin. Any faster and it blows

 

[AndreL]

That was very "insightful" High

 

[Lonyo]

DVD cannot go above 16x or the discs will shatter and be destroyed, and possibly destroy or damage the drive.
Even at 52x CD's get hot and there's a risk of shattering, definately moreso at higher speeds, so the limit is the limit of the media, they just cannot spin any faster
(You wouldn't want your car engine running into the red on its rev's, because it might break, same is true of CD's).

 

[LTC8K6]

CD's and DVD's are spinning at very high speeds these days, they really can't go much faster.

They are over 10,000rpm on the high speed drives. Spin them much faster and you are asking for trouble.


CD Explode

 

[Jeff7]

Originally posted by: LTC8K6
CD's and DVD's are spinning at very high speeds these days, they really can't go much faster.

They are over 10,000rpm on the high speed drives. Spin them much faster and you are asking for trouble.


CD Explode

Excellent website there - that guy's other projects are incredible.

 

[VirtualLarry]

The problems with high-speed CD rotation are two fold, but related. Spinning a CD disc at extremely high speeds, can cause even the most minute imbalance to create serious vibration and instability, and can cause difficulty tracking the CD while reading, especially at the outside. The other problem, is the material instability at high speeds, and the stress that the polycarbonate substrate has to endure. Some "imperfect" CDs can actually shatter at high speeds, many times destroying the drive along with it.

Personally, I've never had that happen, and I've only had a single warped CD vibrate in my drive bad enough that I thought that it might explode on me. I own a 56X IDE Afreey CD-ROM, that was built before high-speed CD shattering became a big deal. Afreey stopped making this model, and now the fastest that they make is a 52X. Likewise, I've only seen 52X, and sometimes 54X readers. I think that the 54X's are actually only 52X, that were tested with 80min CDs to make them bench as 54X at the outside.
I also own a re-flashed Sony drive with Lite-On 52x24x52 firmware. I have no problems with either one, although I tend to get higher-quality results when running them at 32X instead of faster.

Btw, once, I had my Afreey somehow glitch, and according to CD-Speed, it was running at nearly 60X speed when done with the graph! (I wish I somehow knew how to get it to do that intentionally. I could have the fastest overclocked CD-ROM drive in the world. ) The increased drive RPMs during that benchmark were also audible, it wasn't just some software anomoly.

The only downside to the Afreey, is that they have EPROM firmware that is not flashable. My current drive reads audio perfectly, but the firmware enforces the inter-track sector gaps that the mixed-mode format specs describe, which means that I can't do full "raw reads" of a mixed-mode disc, I get 150 sectors of pure zeros between the data track and subsequent audio tracks. This causes minor issues with some copies, because the original masters didn't fully adhere to the spec, so I lose some of the first few frames of audio from the first redbook audio track on a mixed-mode disc.

I would read in my Sony/Lite-On, but it has problems properly reading the sub-code indexes from redbook audio tracks. My SCSI Yamaha 6416S was the best audio subcode reader I had, but it's "retired" now.