Random play on CD or DVD

how does randomness actually work on a player?   ie:  do they use a sample of the AC current for those types?  Is there an oscilator chip of some sort at work?  How would the player get the initial seed?   Do most CD/DVD players have a clock, if so, does the seed come from that, even though most people never set their clock?

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HJohnsonAsked:
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SaMuElCommented:
I believe it's done software side.
i.e. windows media player would be coded to randomize the track, and then order the CD drive to play that track. In fact I think from experience windows media player selects randomly from the list of tracks that haven't been played yet.
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HJohnsonAuthor Commented:
Sorry, I didn't mean a PC, but an actual standalone player.  
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HJohnsonAuthor Commented:
In order to get the first "random" track, you've got to get a seed of some sort.  Normally, this seed would be from a time stamp.
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RyanChCommented:
I believe that a CD player's form of a random seed isn't exactly what we would consider 'random', because of the problem you highlighted.  It is possible that it generates a random number using some form of built in clock, or, more likely, its psudeo-random, generated like those of some basic scientific calculators.  I believe they have basic chips which allow for psudeo randomization without a clock.  It is a very interesting point you bring up, I have never thought of it in detail.
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SaMuElCommented:
Hmm, I guess it would vary from player to player. They all would have a timer of sorts, which would be used as a seed from the person pressing play.
Maybe it's continually on, or maybe they measure the amount of time the play button was depressed. I'm only guessing :)
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SICMASOCommented:
From what I know (since I’m a programmer) every player (at list for most of them) use randomize function.
Basically player read number of track that CD has and then puts it into this Randomize Functions that spits out random number from the range of value it was given. If you want to know how actually the Randomize function work it another story. But here is the short version. Randomize function is not truly random. There is NO RANDOMness  in a computer…..
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SaMuElCommented:
There's no randomness anywhere. Everything has a definite next step, there's only uncertainty :)
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RyanChCommented:
"If you want to know how actually the Randomize function work it another story"  I think thats exactly what we're looking at.  As you said there is no such thing as purely random in a computer chip, but usually a seed timer, like a clock, is used to generate seed values to which psudeo randomization is applied.  In a CD player the question is, what device sets the seed for the psuedo randomization, which I am guessing would probably apply to many calculators as well...and i'm sure other devices use randomization without a clock seed.
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HJohnsonAuthor Commented:
Lots of personal comments, but where's the proof?  (Where's the Beef!!)
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SaMuElCommented:
I don't think we can prove it, unless someone has the circuit diagram & source code for a specific model, and only then can we be certain it applies to that specific model.
Maybe you could contact the engineering division of Sony or something :|
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HJohnsonAuthor Commented:
thnx guys, I have a feeling that an internal chip of some sort is responsible.
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