CD Timing - more than 80 mins?

[romualdo]

I didn't think it was possible to have more than (up to) 80 minutes of recorded data/music on a standard CD

I've just received a Horace Tapscott & Michael Session Japanese P-Vine disc "Live At Theatre Du Chene Noir, Avignon, France 1989"

It's showing as 83 minute duration - have there been changes in technology?

[Rooster_Ties]

A little bit, but I understand they don’t confirm to what I think is called the Redbook standard (if I remember my terminology right). I have one or two “real” CD’s that are just slightly over 80 minutes — the Lou Blackburn two-fer that BN put out (of his Imperial sessions) is one, and I’m not recalling the other.

Also, iirc, some CDR’s can be pushed to record slightly more than 80 minutes — before rereading your post, was gonna say up to about 82 minutes — but maybe it’s slightly higher than that too.

I’m absolutely certain there are one or two threads on the subject over at the Steve Hoffman Forums — probably extensive threads — and when I get the chance, I’ll see if I can find them and post some links.

[T.D.]

I have some classical CDs, all in box set reissues, that run slightly over 80 minutes.

Never before heard of one as long as 83 min.

My player gets sketchy on super-long CDs and sometimes has trouble reading them.

[chewy-chew-chew-bean-benitez]

redbook was 74 wasnt it, theve been going over for decades though

[Kevin Bresnahan]

When a CD is made with more than 74 minutes of audio on it, the pit spacing rules need to be ignored. Basically, the lands and pits are closer together, and due to the wavelength of the laser, it becomes more difficult to read.

Here's a cartoon that shows what the digital data looks like (I think this is exaggerated for simplicity):

That 1.6 µm spacing is the "redbook standard" spacing that enables the laser to properly read each "track" of 1's & 0's.

CDs hold about 700 MB of data in a 120 mm (4.75 inch) CD. So how does a DVD hold so much more than that? Or a BluRay? As most know, a single-layer DVD-R's can store up to 4.7 GB. That's almost 7 times as much data. That's because the DVD pit spacing standard is .74 µm. This data is read back by a different wavelength laser. CD lasers operate at 780 nm. DVD lasers operate at 650 nm (Blue Ray lasers are only 405 nm). Smaller wavelength means smaller illumination area which allows for tighter spacing.

Laser wavelength comparison:

CD vs. DVD pit spacing comparison:

If someone wanted, they could make a CD player that used a DVD or BluRay laser and fit a lot more music on this 120 mm disc. However, that would need to be done by creating a new "standard" playback format (and player). Could be done, but very doubtful. I suppose being able to get a 7 CD Mosaic box set on 1 single disc would be nice, but not many people want or need that much music on one disc.

[sonnymax]

Thanks, Mr. Wizard. I knew we could count on you! 

 

[Teasing the Korean]

Just curious, for backup purposes, are these discs hard to extract?  I know that it is very difficult if not impossible to extract hidden tracks that appear as negative numbers before track 1.

[mikeweil]

2 hours ago, bresna said:

I suppose being able to get a 7 CD Mosaic box set on 1 single disc would be nice, but not many people want or need that much music on one disc.

With SACD this is no problem. But I guess labels will rather sell seven than one disc.

[Kevin Bresnahan]

1 hour ago, sonnymax said:

Thanks, Mr. Wizard. I knew we could count on you! 

 

I was always more of a Mr. Peabody fan than Mr. Wizard. Mr. Peabody was a scientist. Mr. Wizard was a... wizard.

 

[T.D.]

3 hours ago, bresna said:

 

If someone wanted, they could make a CD player that used a DVD or BluRay laser and fit a lot more music on this 120 mm disc. However, that would need to be done by creating a new "standard" playback format (and player). Could be done, but very doubtful. I suppose being able to get a 7 CD Mosaic box set on 1 single disc would be nice, but not many people want or need that much music on one disc.

Thanks for the tech info (snipped).

Braxton has been releasing a significant amount of physical material, music and video, on Blu-Ray discs.

For instance this one, which is iirc 4 to 5 CDs equivalent on 1 Blu-Ray disc.

[romualdo]

5 hours ago, Teasing the Korean said:

Just curious, for backup purposes, are these discs hard to extract?  I know that it is very difficult if not impossible to extract hidden tracks that appear as negative numbers before track 1.

had no trouble extracting this recent 83min disc

[Teasing the Korean]

12 minutes ago, romualdo said:

had no trouble extracting this recent 83min disc

Thanks!

[miles65]

My CD with all 6 Brandenburg concerto's from J.S Bach New Complete Edition clocks 86'19''