Speaking of CD Burning

[Duane Attaway]

On Thu, 17 Oct 2002, Jonathan Hutchins wrote:

> Why can't you just take an ISO of the audio CD and copy it?  Or, for that
> matter, mount it through loopback?
> (I'm gonna have to try when I get home.)

Good question.  When I tried, my computer burped the following back at me:

root at satellite root # cat /dev/cdrom
cat: /dev/cdrom: Input/output error

So I dug around cdparanoia's faq and found technical reasoning why a cd 
can't be read directly:

  Unfortunately, it isn't that easy.

  The audio CD is not a random access format. It can only be played from
  some starting point in sequence until it is done, like a vinyl LP.
  Unlike a data CD, there are no synchronization or positioning headers
  in the audio data (a CD, audio or data, uses 2352 byte sectors. In a
  data CD, 304 bytes of each sector is used for header, sync and error
  correction. An audio CD uses all 2352 bytes for data). The audio CD
  *does* have a continuous fragmented subchannel, but this is only good
  for seeking +/-1 second (or 75 sectors or ~176kB) of the desired area,
  as per the SCSI spec.

  When the CD is being played as audio, it is not only moving at 1x, the
  drive is keeping the media data rate (the spin speed) exactly locked
  to playback speed. Pick up a portable CD player while it's playing and
  rotate it 90 degrees. Chances are it will skip; you disturbed this
  delicate balance. In addition, a player is never distracted from what
  it's doing... it has nothing else taking up its time. Now add a
  non-realtime, (relatively) high-latency, multitasking kernel into the
  mess; it's like picking up the player and constantly shaking it.