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From: "Jason Pyeron" <jpyeron AT pdinc DOT us>
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References: <214132B8041D40F5AF9B78919F033F6F AT phoenix> <0105D5C1E0353146B1B222348B0411A2A4000440 AT NIHMLBX02 DOT nih DOT gov>
Subject: RE: Wodim and ramping up speed [OT]
Date: Mon, 11 May 2009 14:20:49 -0400
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> -----Original Message-----
> From: Buchbinder, Barry (NIH/NIAID) [E] 
> Sent: Monday, May 11, 2009 13:10
> Subject: RE: Wodim and ramping up speed
> 
> Jason Pyeron wrote on Monday, May 11, 2009 12:33 PM:
> > I was just wondering if this is proper as it struck me as odd.
> 
> No, it is not proper.  It is off-topic for this mailing list. 
>  As far as I know, cygwin does not interact directly with 
> hardware.  

I was asking here, as wodim does not have a user list, and it is a cygwin port.

It asks Windows to do that.  So speed issues will 
> usually depend on the capabilities of Windows and the 
> hardware, not cygwin, and thus OT.
>  
> > I know that the maximum data throughput on a device is a 
> function of 
> > the radius and rotation speed, but why doe the disc speed (not write
> > speed) change?  
> > 
> > In fact it changes when the write speed changes too.
> 
> That is true for hard disks.  Audio CDs store data in a 
> spiral, not ring-like tracks.  They are read at constant 
> linear velocity.  See

Thanks, learn something new every day.

>     http://en.wikipedia.org/wiki/Compact_Disc#Main_physical_parameters
>       Scanning velocity: 1.2-1.4 m/s (constant linear velocity) -
>       equivalent to approximately 500 rpm at the inside of the disc,
>       and approximately 200 rpm at the outside edge Verifying 
> that the same is true for data CDs is left as an exercise for 
> the reader.
> 

Then that would explain why the drive speed changes, but not why the data rate
is changing.

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