[78-L] CD playing speed

[Michael Biel]

P G C wrote:
> So the question changes:
>
> Which would be the standard 1X tangential speed?
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>   

I think it is more understandable if you use the terms "rotational 
speed" and "linear speed".  In addition to the formats already 
discussed, there were two systems used for LaserDiscs, CAV and CLV.  The 
long play mode was CLV which was Constant Linear Velocity, which meant 
the speed of the reading was constant as the rotational speed changed to 
meet the changing reading diameter.  CAV was Constant Angular Velocity 
where the rotational speed was constant and provided one full video 
frame per revolution.  (Freeze Frame was easy -- just keep the laser in 
place!) You look at those discs and you can see the placement of each 
scanning line and where the two frame interlaces are, with them 
radiating out from the center to the rim in straight lines at a 
V-angle.  That's why they used the name including the word Angle.  But 
that is confusing for anything but LaserDiscs, so that should be 
discussed as "constant rotational speed" for other systems. 

Mike Biel  mbiel at mbiel.com

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> ________________________________
> From: Chris Zwarg <doctordisc at truesoundtransfers.de>
> To: 78-L Mail List <78-l at klickitat.78online.com>
> Sent: Wednesday, December 3, 2008 11:03:27 AM
> Subject: Re: [78-L] Record playing speed ^
>
> At 17:57 03.12.2008, you wrote:
>   
>> I am lost here, isn't rpm the same in the inside and in tha outside, the other, the tangential speed, ok this is is variable.
>>
>> Am i wrong?
>>
>>     
>
> With CDs, the tangential speed is constant, the rpm is constantly adjusted accordingly in the player/burner. With conventional disc records it obviously isn't (that's how the familiar "end-of-side distortion" heard on slightly worn records occurs - reproduction gets more difficult towards the center of the disc).
>
> Chris Zwarg