So, it came up amongst some of my fellow computer geeks today and we’ve been unable to locate a reason: we have double-sided DVD’s, why no double-sided CD’s? Is such a critter possible? Rare? Extinct? Does anyone have any thoughts?
For how CD’s are constructed:
Versus DVD’s:
InkBlot
I saw one once.
It seemed more like two cds glued back-to-back though
Double-sided CDs are expensive, more prone to failure, and there’s nowhere to put a label or hold the disc. One side already holds 74 minutes, another 74 isn’t really necessary.
Given economy of scale issues, it’s cheaper to make 2 CDs than 1 double sided CD. There’s a lot of single sided CD pressers in the world.
Yea, so why didn’t those same reasons stop them from making double-sided DVD’s? Granted there would be no point now-a-days to make double-sided CDs. but back in the day it could have been handy.
Those exact reasons did stop them from making double-sided DVDs, kenh_77. You might have noticed that no DVDs released in the past few years have been double-sided.
Well, thinking of a 45, they could use 75% of the radius as data, and the other 25% to paste/print a label, on both sides. This is effectively giving you 50% more data all together.
On a side note, i saw a CD the other week, where the label side was black plastic, with concentric circles etched on it. It looked like a 45 LP! It was awesome!
That’s not true. This double-sided DVD was released April 2003:
OK, most DVDs released in the past few years have not been double-sided. 
It would probably have to be the outer 25% of the radius, so the label would be more like a ring around the edge of the disc.
The reason for this is that, unlike vinyl, cd tracks start at the inside and spiral their way toward the outer edge - I suspect that many CD players would simply see the disc as unreadable if you moved the position of the first track.
There used to be a lot more double-sided DVDs because dual-layer discs were harder/more expensive to press. Some movies had to be flipped over in the middle, because each single-layer side could only hold half the movie.
Now the costs have come down, and double-sided DVDs are only used when there’s so much video that it can’t fit on a dual-layer side (e.g. widescreen and fullscreen versions, or lots of special features).
A double-sided CD would be easier to smudge, but harder to seriously damage. A scratch on the bottom of will keep the laser from reading part of the disc, but it can be resurfaced; a scratch on the top that cuts through the label will destroy some of the data.
The West Wing Complete Season 1 dvd set, released in the US last month, uses four double-sided dvds.
Many DVDs are released as double sided discs where the widescreen version is on one side and the fullscreen version is on the other. Off the top of my head, I can’t remember the last movie I bought like this, but I have many of them in my collection.
Porno DVDs come out double-sided all the time.
Um, I’ve heard.
Needless to say, I guess, double-sided DVD’s are common enough…whether or not they’re still produced regularly. But does anyone know if a double-sided CD is possible or exists? I can accept that the design specification for CD readers doesn’t allow it, even if the construction should easily be feasible. I mean, most of a CD is a layer of plastic…maybe it must be a certain thickness or something. Seems like a stretch to me, but anyway…
Thanks for all the input so far.
InkBlot
Well, the original DVD-specs allowed for a dual-sided disc, but that’s not the case with CD-specs. Since the data on a CD is stamped onto the top-side of the disc, dual-sided CD would need to be double thick as the lasers are focused to read through a certain depth of base material.
Small correction: one CD can hold about 80 minutes of music.
There are plenty of occasions where even 80 minutes is not enough (think operas), but as stated before, using a number of one-sided discs is just as effective and a lot cheaper.
I think you’ll find that double-sided DVDs are also thicker than single-sided DVDs. They’re made just the way you’d expect double-sided CDs to be made: two single-sided discs are pressed and then glued together.
Dragon Phoenix, the original spec was 74 minutes. 80 minute discs are a relatively new invention.
I’m sure I have CD’s in my collection of about 12 years old which have close to 80 minutes music on them. The original spec was indeed 74, but that was changed quite some time ago.
A couple questions…
First, how do the full season double DVDs let you know which side is side 1 and which is 2? Do they do different color plastic on each side?
And could a CD drive be built to readjust its focus depth? I know that one probably wouldn’t be made, as there would be very little demand, but could that be done?
And are blank double sided CDs still manufactured?