CD, DVD, and Blu-Ray

[Brute]

I'm gonna start this by saying that even though I'm a young adult, I'm not all that tech-savvy.

So, I know that CD's are usually used for music and stuff, and I guess that can hold somewhere in the neighborhood of .75 GB. I always saved my stuff onto a CD when I had to reformat my computer, back in the days of the horrible Windows ME. I couldn't do that now, not with all my music and photos... Then there's DVD's. This is where I get really confused. What really is the difference between CD and DVD? I mean, is it the way things are saved on a CD, or is the DVD a totally different type of disk?

I feel kinda dumb for asking this, but I guess it's time I get to know these things

I do believe I know what a blu-ray disk is. It's a new type of disk where things are compressed more, and a blue ray is used to read it, instead of the red ray used for other things. I can't wait to get movies on blu-ray disks. HD!!!
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[Jacky]

CDs used to be popular at a time when files do not fit into floppy disks and USB drives are just too expensive at that time with meagre capacity. I remember saving my school work on a CD-RW.

I also used to save my files on a CD but some things just get bigger as technology advances, such as file sizes. I have switched to saving my files on DVDs and even DVD DL (double layer).

It's the type of laser used to shine on it. The lasers used for DVDs are finer than those for CDs, and those on BD are finer than those for DVDs.

From finest to fine:

BD > DVD > CD

It's not about the compression actually, like I mentioned earlier, is the laser used to read data off the disc. It's actually a blue-violet laser rather than just totally blue.

I believe you also know about the now defunct HD-DVD.
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[Brute]

Ok, I guess I get it now. So my computer, which can read CD and DVD, must have multiple lasers? Also, when do you think the "BD" will totally take over, or will it? For some things, CD's work fine. Like for music, they easily hold the typical amount of songs you would have on one album.

Well, I heard of the HD-DVD, but I don't think it really ever became big..? I still watch normal DVD movies.
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[LP-SolidRaven]

And to add to jacky his comment:
DVD laser is 650nm wavelength.
CD laser uses 780nm wavelength if I remember correctly.
And Blu-ray uses 405nm.

And for your interested in how those lasers might look:
CD laser is just outside the visible spectrum (380nm -> 750nm).
DVD laser will be red.
And the Blu-ray laser is violet.

This also explains why a Blu-ray disk can store more than a DVD.
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Dilly dally, shilly shally.

[mcwkm]

All 3 formats have purposes right now. This is all because of cost. Blank DVDs cost more than blank CDs so when someone wants to make a disc that fits on a CD, they use the CD to be cost efficient. The price of the actual DVD lasers as well as CD lasers have come down and the difference on a consumer level is not that much so when buying the drive, it really doesn't make much of a difference anymore seeing how they both cost within $20 to $30 of each other max. BlueRayDisc on the other hand is very expensive and is a luxury format right now. As technology advances the prices will probably drop but it will still stay above that of DVD.

I don't see any of the formats dying soon but one will eventually die. I know a lot of people my age who wouldn't know a floppy disc if I shoved one in there face. I know even more people who don't know what a 5-inch floppy disc is. The reason I don't see any of the formats dying out is because I don't see the price of the superior format matching the price of the lower format anytime soon. The other factor which is why floppy discs are so rare now is because of storage capacity. Each can hold a different maximum and unless the capacity of a CD cannot hold a decent amount of documents/media it won't disappear until something is cheaper
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[LP-Trel]

Look at it this way:

CD: 800MB capacity and very cheap.
DVD: 4GB capacity and still cheap while more expensive than CD.
DVD DL: 8GB capacity and more expensive still, but still pretty cheap.
Blu-ray: 50GB capacity and very expensive with limited compatibility.

In my humble opinion optical media is a dying format. You can buy 250 - 500GB portable hard drives for as little as $60 - $100 now. That is very hard for optical media to compete with considering price per GB since portable hard drives are easily reused.
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[mcwkm]

I prefer optical format, hard drives can be damaged much easier and loss of your data cause loss of money. But you maybe right that most people will switch to different format since a lot of media is being offered as downloadable content.
Also aren't there like ridiculous blu-ray discs that hold insane capacities, they just aren't available.
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[LP-Trel]

[Jacky]

[LP-SolidRaven]

Shouldn't be too hard to put read only memory in a flash drive I guess. Would also make a few rather nice security possibilities possible.
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Dilly dally, shilly shally.

[Myst]

I think optical media has it's place for giving files to other people. Although flash memory is becoming cheaper, it's still substantially cheaper to give someone something on a DVD, rather than a USB flash drive.

In Australia, the cheapest you'll get (say) a 4 gig memory stick is around $20. For that $20, you can get 50 blank DVDs. That's a hell of a lot more storage for the same price.

I also don't think reusability is necessarily a huge advantage either - simply because I like to have a permanent copy of things

The other huge use for Optical Media is, well, media. Movies, music and games (especially console games), I think, are likely to keep it going for a while longer. Everyone has a CD player, and DVD player. With Blu-ray coming in, I think it's likely that will stay around for at least 7-8 more years. And the next generation of consoles will also likely use Optical Media (there isn't really a viable alternative at the moment - and I doubt one will present itself in time).