Re: CD writing in future Linux (stirring up a hornets' nest)

[Sam Vilain <sam@vilain.net>]

D. Hazelton wrote:
> > > This value is also reported by the drive. I don't know about DVD drives,
> > > but for CD drives it is a multiplier. 1x == 256K/sec transfer off the
> > > disc [...]
> > For CDs, 1x is actually 150 KByte/sec.
> Well, I've been known to be wrong before, and this number was more based on 
> the fact that I once measured a sustained transfer rate of 1M/sec on a 4x 
> CDROM
Think about audio.  Single speed = 75 frames of 2352 bytes per second, 
or 176kB/s.  However with data tracks you only get 2k per frame/sector, 
so that works out to be 153kB/s.
Due to the CLV nature of CD-ROMs you may find the drive is faster 
reading some parts of the disc than others.
> > According to WikiPedia, the DVD speed rating is almost 9 times that of
> > CD speeds. I.e., 1x DVD is about 1.32 MByte/sec.
> This was based on DVDx16 == CDx48 - I'm guessing someone is doing some monkey 
> work if a DVD is 9x a CD and a 16x DVD can't hit that mystical 52x of my 
> favorite CDRW drive in pure CD read mode.
You can do a similar calculation with DVDs.  While I can't find a 
reference for the maximum DVD total bitrate of ~10Mbit/s, this at 1.25 
MByte/s this roughly agrees with the 1.32 quoted.
Sam.
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