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Which side of DVD/CD is "read"?


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The transparent under side or the label top side? I recall recently reading the label side is read, and I have begun to doubt my recallation. Does it make any sense trying to clean prints and dust from either side of rental disks? Are "scratches" the only thing that would cause problems?

Probably will regret submitting this, given how stupid it makes me look!

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The laser reads from the bottom of the CD, the transparent side. However, if I remember correctly, the data is directly under the top label, so a scratch to the top of a cd can damage the data permanently.

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Well, here's another dumb question...these new yet-to-be-released DualDiscs that's a CD on one side and a DVD on the other...is there a label on one side or the other, or are they blank on both sides? At this time, would anyone even know yet?

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On 5/9/2004 5:21:12 PM bdc wrote:

The laser reads from the bottom of the CD, the transparent side. However, if I remember correctly, the data is directly
under
the top label, so a scratch to the top of a cd can damage the data permanently.

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Yep. The plastic layer of the CD/DVD is simply there to protect the data. The laser is placed under the disc, passes through the transparent layer, reflects off of the aluminum layer back to a sensor. Therefore, if you use anything other than a felt tipped marker to write on your discs, you are either going to remove the layer, or crinckle the data which is far worse than any fingerprint or scratch.

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On 5/9/2004 5:31:22 PM jt1stcav wrote:

Well, here's another dumb question...these new yet-to-be-released DualDiscs that's a CD on one side and a DVD on the other...is there a label on one side or the other, or are they blank on both sides? At this time, would anyone even know yet?

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I haven't heard anything technology-wise about these discs yet, but I'm going to assume they do it the same as a dual-sided DVD. With those, the data material is sandwiched between two layers of the plastic and sealed with some type of glue.

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I wouldn't know...I'm the only one in the house that doesn't own a HT or a DVD or SACD player. I buy DVDs, but I never mess with my brother's HT systems, therefor I never use their DVD players. I have no clue how to set their AV receivers, or how to configure their DVD players for 7.1 DD or DTS, etc., etc.

I'm just a simple 2-channel freak!3.gif

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On 5/9/2004 9:14:02 PM garymd wrote:

If you want widescreen, I believe you would put if face down. I haven't played one in a long time but I'm 99% sure that's how it works. If you don't get w/s, flip it over.
2.gif

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I thought it was the other way around. If you want widescreen, put "widescreen" up (it's like the label of that disc). I only have a few other these and they all work this way - but I certainly can't conclude it's universal with a sample of 3!

Speaking of this, why aren't more DVD's available like this? I remember when DVD's came out this was one of the things they really pushed in the marketing. I guess most people have a preference and only watch one format anyway.

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In all the CD players I have, the laser and optics read the down side. The optics are below the tray. Taking some of them apart confirms this.

For example. My little cheapo Sony - Sears player will read a DVD and a CD. The CD and DVD's work with the label side up. Hence even with a double sided DVD, it is only reading the down side.

Gil

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Well, me and a friend of mine burned a CD and it wouldn't work for some reason. So we didn't care much for it but when we looked at it, the CD seems only to be 2 stickers on plastic. The plastic is to help keep its shape. You have the label side and bottom part which has the info on it containing 1s and 0s.So in reality, the space needed for the info is only the depth of a sticker. At least when looked at the disk thats what I noticed. I guess bit off topic, we played with the CD like a frizbee. Kinda fun but sucks it didn't work. Darn windows huh. This was back when windows 98 was conisdered new.

CD

I just noticed my sign off sig is also about what I was talking about. How ironic and no pun intended.

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On 5/9/2004 11:11:53 PM Darren wrote:

I thought it was the other way around. If you want widescreen, put "widescreen" up (it's like the label of that disc). I only have a few other these and they all work this way - but I certainly can't conclude it's universal with a sample of 3!

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You are correct as the generally accepted way is to treat it like a label (so Widescreen text faces up when watching the widescreen version) but there are a few exceptions to this rule... like the Blue Man Group's DVDA/DVDV which is actually labelled the opposite way. But this is the only disk I've had like that.

Another note is that the DVD standard is actually setup to have the possibility of 4 layers of data (±19GB data)... two on one side and two on the other. This is what the 16:9/4:3 disks are. Since all the common machines available read only from the bottom side, a dual layered dual sided disk would still require the user to manually flip the disk.

Most bought disks are dual layer (9.4GB data)... 2 layers on one side and a label on the other. The head focuses on either layer from the bottom. Most burnt disks are single layer (4.7GB data) and that is why the data has to be compressed to make a backup .

Just some useless DVD info...

Rob

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just to echo what formica said and possibly put to rest a curious event that you probably notice...

when watching a dvd, somehere in the middle of the movie or so, usually between a scene change, the picture and audio seems to pause just for a second...then pick back up. that is the transition point from reading one layer to the next.

drove me nuts, i thought it was my dvd player, but after some research found out that little fact.

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On 5/11/2004 1:46:08 PM tankhokie wrote:

just to echo what formica said and possibly put to rest a curious event that you probably notice...

when watching a dvd, somehere in the middle of the movie or so, usually between a scene change, the picture and audio seems to pause just for a second...then pick back up. that is the transition point from reading one layer to the next.

drove me nuts, i thought it was my dvd player, but after some research found out that little fact.

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I always wondered what that pause was about. Seems to happen once on every dvd. Thanks for the explanation.

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On 5/9/2004 5:46:06 PM jt1stcav wrote:

"I see", said the blind man.
2.gif

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Blind man walks into a store with his seeing eye dog !

The man picks up the dog by the tail and starts swinging it around !!!

A terified store clerk screams at the guy " Hey what the hell are you doing "

The blind man replies " Just taking a look around " !!!!!!!!!!

9.gif9.gif9.gif9.gif9.gif9.gif

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