Subversion Repositories planix.SVN

.TH CDFS 4

.SH NAME

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

.SH SYNOPSIS

.B cdfs

[

.B -d

.I sddev

] [

.B -m

.I mtpt

]

.br

.B "grep aux/cddb /mnt/cd/ctl | rc

.br

.B aux/cddb

[

.B -DTt

] [

.B -s

.I server

]

.B query

.I diskid

.I ntracks

.I track0id

.I ...

.SH DESCRIPTION

.I Cdfs

serves a one and a half level directory

mounted at

.I mtpt

(default

.BR /mnt/cd )

that provides access to the tracks

on discs placed in the disc reader or writer

named by

.I sddev

(default

.BR /dev/sdD0 ,

see

.IR 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.

.PP

The top level directory contains one file

per disc track.

The files are named

.IR cNNN ,

where

.I c

is a type character

.RB ( a

for audio tracks

and

.B d

for data tracks)

and

.I NNN

is the track number.

.PP

If the device can write discs

and contains a writable disc, the top-level

directory also contains an empty directory

.B wd

and, for CDs only,

an empty directory

.BR wa .

Files created in these directories

appear in the top-level directory

as new data or audio tracks, respectively, regardless of name.

.PP

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 transparently.

To ensure saturation, copying from a file system

stored on local disk or memory is recommended.

.PP

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.

.PP

To fixate a disc (close a recordable disc by writing

its permanent table of contents), simply

remove the

.B wa

or

.B wd

directory.

The directory removed selects whether

the disc is fixated as an audio or data disc;

since each track carries its own type information,

very few readers care which fixation type was used.

Rewritable discs do not require fixation.

.PP

The top level directory

also contains a

.B ctl

file, into which control messages

may be echoed.

The current control messages are:

.TF \fLquickblank

.TP

.B format

Format the rewritable disc (\c

.B -RW

or

.BR -RE )

in the drive

before initial use.

.TP

.B blank

Blank the entire rewritable disc in the drive.

.TP

.B quickblank

Blank only the table of contents on the rewritable

disc in the drive.

.\" .TP

.\" .B closetracks

.\" Close any open tracks on the current disc but do not finalize (fixate) the disc.

.TP

.B eject

Eject the disc in the drive.

.TP

.B ingest

Ingest a disc into the drive.

.TP

.B speed \fIkbps\fR

Set the reading and writing speed to use,

in units of 1,000-bytes-per-second.

A value of

.L best

requests the optimal speed for the current drive and disc.

CD

.L 1x

speed is 154;

DVD

.L 1x

speed is 1350;

BD

.L 1x

speed is 4608.

Drives may round down the speed to one they support.

To set reading and writing speeds separately,

prefix the speeds with

.B read

or

.BR write ,

as in

.B speed

.B write

.B 8192

or

.B speed

.B read

.B 16384

.B write

.BR 8192.

Note that most drives reset the reading and writing speed

each time a new disc is inserted.

.PD

.PP

Reading the

.B ctl

file yields information about the drive.

If the drive contains an audio CD, the first line

will be an

.B aux/cddb

command that can be run to query

an internet CD database

to get a table of contents.

Subsequent lines contain the current and maximum

reading and writing speeds.

Additional lines may further describe the current disc.

.PP

.I Aux/cddb

takes 4 optional arguments.

The

.B -s

option makes

.I aux/cddb

use

.I server

for the query instead of

.LR freedb.freedb.org .

The

.B -D

option causes the raw database response from the server to be dumped

to standard output.

The

.B -t

option causes the time of each track to be appended to the normal output.

.B -T

is like

.B -t

but prints a final line with the total time.

.br

.ne 6

.SH EXAMPLES

Backup to a BD-R disc:

.br

.ne 3

.IP

.EX

9fs boot

cdfs

tar cf /mnt/cd/wd/x /n/boot

.EE

.br

.ne 3

.PP

Copy the audio tracks from a CD:

.IP

.EX

cdfs -d /dev/sd05

mkdir /tmp/songs

cp /mnt/cd/a* /tmp/songs

.EE

.PP

Copy the tracks onto a blank CD inserted in the drive,

and then fixate the disk as an audio CD.

.IP

.EX

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

rm /mnt/cd/wa

.EE

.SH SOURCE

.B /sys/src/cmd/cdfs

.SH SEE ALSO

.IR pump (1),

.IR sd (3),

.I 9660srv

(in

.IR dossrv (4)),

.IR mk9660 (8)

.PD 0

.TF "\fLhttp://www.t10.org\fP"

.TP

.B http://www.t10.org

optical disc interface standards,

notably

.I "Multi-Media Commands"

(MMC)

.PD

.SH 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

.IR sd (3).

There's no need to fixate data discs, except to prevent adding new tracks.

.PP

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.

.PP

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.

.PP

Only MMC-compliant disc readers and writers

are supported, but it would be easy to add

support for early CD writers if desired.

.PP

.I Cdfs

can take some seconds to figure out that it has

a BD in the drive and how many layers are on the disc.