CDFS(4)                                                   CDFS(4)

     NAME
          cdfs, cddb - optical disc (CD, DVD, BD) track reader and
          writer file system

     SYNOPSIS
          cdfs [ -d sddev ] [ -m mtpt ]
          grep aux/cddb /mnt/cd/ctl | rc
          aux/cddb [ -DTt ] [ -s server ] query diskid ntracks
          track0id ...

     DESCRIPTION
          Cdfs serves a one and a half level directory mounted at mtpt
          (default /mnt/cd) that provides access to the tracks on
          discs placed in the disc reader or writer named by sddev
          (default /dev/sdD0, see sd(3)). Any MMC-compliant compact
          disc (CD), DVD, or Blu-ray disc (BD) drive should work.  On
          DVDs and BDs, access to data tracks only is implemented.

          The top level directory contains one file per disc track.
          The files are named cNNN, where c is a type character (a for
          audio tracks and d for data tracks) and NNN is the track
          number.

          If the device can write discs and contains a writable disc,
          the top-level directory also contains an empty directory wd
          and, for CDs only, an empty directory wa.  Files created in
          these directories appear in the top-level directory as new
          data or audio tracks, respectively, regardless of name.

          At any time, any number of tracks may be open for reading or
          a single track may be open for writing.  Writing a disc
          track is a quasi-real-time operation: the disc writer should
          be kept saturated with new data to avoid buffer underruns,
          but modern drives will be told to cope with underruns trans-
          parently.  To ensure saturation, copying from a file system
          stored on local disk or memory is recommended.

          BD-R discs are `formatted' upon first use, for sequential
          writing with spare sectors for hardware defect management,
          so BD drives should not report errors when writing BD-R
          discs; any such errors may be a sign that the laser of an
          old drive is fading.

          To fixate a disc (close a recordable disc by writing its
          permanent table of contents), simply remove the wa or wd
          directory.  The directory removed selects whether the disc
          is fixated as an audio or data disc; since each track car-
          ries its own type information, very few readers care which
          fixation type was used.  Rewritable discs do not require
          fixation.

     CDFS(4)                                                   CDFS(4)

          The top level directory also contains a ctl file, into which
          control messages may be echoed.  The current control mes-
          sages are:

          format      Format the rewritable disc (-RW or -RE) in the
                      drive before initial use.
          blank       Blank the entire rewritable disc in the drive.
          quickblank  Blank only the table of contents on the rewrit-
                      able disc in the drive.
          eject       Eject the disc in the drive.
          ingest      Ingest a disc into the drive.
          speed kbps  Set the reading and writing speed to use, in
                      units of 1,000-bytes-per-second.  A value of
                      `best' requests the optimal speed for the cur-
                      rent drive and disc.  CD `1x' speed is 154; DVD
                      `1x' speed is 1350; BD `1x' speed is 4608.
                      Drives may round down the speed to one they sup-
                      port.  To set reading and writing speeds sepa-
                      rately, prefix the speeds with read or write, as
                      in speed write 8192 or speed read 16384 write
                      8192.  Note that most drives reset the reading
                      and writing speed each time a new disc is
                      inserted.

          Reading the ctl file yields information about the drive.  If
          the drive contains an audio CD, the first line will be an
          aux/cddb command that can be run to query an internet CD
          database to get a table of contents.  Subsequent lines con-
          tain the current and maximum reading and writing speeds.
          Additional lines may further describe the current disc.

          Aux/cddb takes 4 optional arguments.  The -s option makes
          aux/cddb use server for the query instead of
          `freedb.freedb.org'.  The -D option causes the raw database
          response from the server to be dumped to standard output.
          The -t option causes the time of each track to be appended
          to the normal output.  -T is like -t but prints a final line
          with the total time.

     EXAMPLES
          Backup to a BD-R disc:

               9fs boot
               cdfs
               tar cf /mnt/cd/wd/x /n/boot

          Copy the audio tracks from a CD:

               cdfs -d /dev/sd05
               mkdir /tmp/songs
               cp /mnt/cd/a* /tmp/songs

     CDFS(4)                                                   CDFS(4)

          Copy the tracks onto a blank CD inserted in the drive, and
          then fixate the disk as an audio CD.

               cp /tmp/songs/* /mnt/cd/wa
               rm /mnt/cd/wa

     SOURCE
          /sys/src/cmd/cdfs

     SEE ALSO
          pump(1), sd(3), 9660srv (in dossrv(4)), mk9660(8)
          http://www.t10.org  optical disc interface standards,
                              notably Multi-Media Commands (MMC)

     BUGS
          Fixating a BD-R disc records only the first track in the
          disc's TOC.  Any other tracks are still there and their data
          accessible via sd(3). There's no need to fixate data discs,
          except to prevent adding new tracks.

          Closing a just-written DVD-R track can take minutes while
          the drive burns the unused part of the track reservation
          (for the whole disc).  Thus only a single DVD-R track can be
          written on a DVD-R disc; use other media if you need more
          than one track per disc.

          There are too many combinations of optical media, each with
          unique quirks, approximately the cross-product of these
          tuples: (CD DVD- DVD+ BD), (-ROM -R -RW), (single-layer
          dual-layer), plus oddities like DVD-RAM.  Triple- and quad-
          layer BD drives and discs are starting to appear.

          Only MMC-compliant disc readers and writers are supported,
          but it would be easy to add support for early CD writers if
          desired.

          Cdfs can take some seconds to figure out that it has a BD in
          the drive and how many layers are on the disc.