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CD-DA sector addressing, was Re: playing CDROM music questions

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Hi,

i cannot contribute much to the practical issues with playing music.
But i'd like to clarify technical properties of CD-DA media:

Nicolas George wrote:
> compared to data CDs, audio CDs lack one layer of error-correcting code

True.

Another drawback is that CD-DA sectors cannot be read by the usual SCSI
commands for hard disk reading, but only by the special command READ CD.

> and [lack] the synchronization necessary to tell the
> position of a particular sector.

Not true. It is possible to read CD-DA with sector granularity.

Random addressing may be somewhat cumbersome for the drive, because the
exact sector address is part of the low level data of the sector.
See MMC-5 4.2.3.5.2 "Mode-1 Q" for how it is implemented on medium and
6.20 "READ CD Command" for how it is to be operated by software of the
hosting computer.

> This is why tools like cdparanoia exist: between one read and the next
> they seek back a few sectors and check that the overlap matches.

If ever it is the drive's firmware which has to guess the position and
then to pick the sectors with the desired address in Mode-1 Q (or in a
neighbor if one of the 10% sectors without Mode-1 Q is desired).

The main reason for specialized CD readers like cdparanoia is rather in
the fact that data readers like mount(8) want to use the general SCSI disk
read commands. There are more reasons, as the man page of cdparanoia
indicates, including workarounds for bugs of antique drives.


Have a nice day :)

Thomas

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Thread

playing CDROM music questions Haines Brown <haines@histomat.net> - 2024-01-08 17:20 +0100
  Re: playing CDROM music questions Nicolas George <george@nsup.org> - 2024-01-08 17:30 +0100
    Re: playing CDROM music questions Haines Brown <haines@histomat.net> - 2024-01-08 22:00 +0100
      Re: playing CDROM music questions Michael Kjörling <2695bd53d63c@ewoof.net> - 2024-01-08 22:20 +0100
        Re: playing CDROM music questions Stefan Monnier <monnier@iro.umontreal.ca> - 2024-01-09 01:50 +0100
        Re: playing CDROM music questions Nicolas George <george@nsup.org> - 2024-01-09 13:30 +0100
          Re: playing CDROM music questions Nicolas George <george@nsup.org> - 2024-01-09 16:20 +0100
          Re: [OFFTOPIC] Filling the FAT (was: playing CDROM music questions) Stefan Monnier <monnier@iro.umontreal.ca> - 2024-01-09 17:00 +0100
            Re: [OFFTOPIC] Filling the FAT (was: playing CDROM music questions) David Wright <deblis@lionunicorn.co.uk> - 2024-01-09 17:10 +0100
              Re: [OFFTOPIC] Filling the FAT Stefan Monnier <monnier@iro.umontreal.ca> - 2024-01-09 21:40 +0100
                Re: [OFFTOPIC] Filling the FAT David Wright <deblis@lionunicorn.co.uk> - 2024-01-10 01:40 +0100
            Re: [OFFTOPIC] Filling the FAT (was: playing CDROM music questions) <tomas@tuxteam.de> - 2024-01-09 18:20 +0100
      Re: playing CDROM music questions "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-01-09 03:50 +0100
      Re: playing CDROM music questions Nicolas George <george@nsup.org> - 2024-01-09 13:30 +0100
  Re: playing CDROM music questions Michel Verdier <mv524@free.fr> - 2024-01-08 17:40 +0100
    Re: playing CDROM music questions Haines Brown <haines@histomat.net> - 2024-01-08 22:10 +0100
  Re: playing CDROM music questions Michael Kjörling <2695bd53d63c@ewoof.net> - 2024-01-08 17:40 +0100
    Re: playing CDROM music questions Nicolas George <george@nsup.org> - 2024-01-08 17:50 +0100
      CD-DA sector addressing, was Re: playing CDROM music questions "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-08 20:10 +0100
    Re: playing CDROM music questions Haines Brown <haines@histomat.net> - 2024-01-08 22:10 +0100

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