libburn/cdrskin/README

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     libburnia-project.org     scdbackup.sourceforge.net/cdrskin_eng.html
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cdrskin. By Thomas Schmitt <scdbackup@gmx.net>
Integrated sub project of libburnia-project.org but also published via:
http://scdbackup.sourceforge.net/cdrskin_eng.html
http://scdbackup.sourceforge.net/cdrskin-1.5.7.tar.gz

Copyright (C) 2006-2023 Thomas Schmitt, provided under GPL version 2 or later.
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cdrskin is a limited cdrecord compatibility wrapper which allows to use
most of the libburn features from the command line.

Currently it is fully supported on GNU/Linux with kernels >= 2.4, on FreeBSD,
on OpenSolaris, and on NetBSD.
IDE drives under Linux 2.4 need kernel module ide-scsi.
ATA and SATA drives under FreeBSD need kernel module atapicam.
On other X/Open compliant systems there will only be emulated drives, but no
direct MMC operation on real CD/DVD/BD drives.

By using this software you agree to the disclaimer at the end of this text
"This software is provided as is. There is no warranty implied and ..."


                   Compilation, First Glimpse, Installation

Obtain cdrskin-1.5.7.tar.gz, take it to a directory of your choice and do:

    tar xzf cdrskin-1.5.7.tar.gz
    cd cdrskin-1.5.7

Within that directory execute:

    ./configure --prefix=/usr
    make

This will already produce a cdrskin binary. But it will be necessary to
install libburn in order to use this binary.

In order to surely get a standalone binary, execute

    cdrskin/compile_cdrskin.sh

Version identification and help texts available afterwards:
    cdrskin/cdrskin -version
    cdrskin/cdrskin --help
    cdrskin/cdrskin -help
    man cdrskin/cdrskin.1


Install (eventually as superuser) cdrskin to a directory where it can be found:
The command for global installation of both, libburn and cdrskin is
    make install
If the library libburn.so.4 is not found with a test run of cdrskin, then
try whether command
    ldconfig
makes it accessible. With the statically linked binary this should not matter.

With that static binary you may as well do the few necessary actions manually.
If cdrskin was already installed by a previous version, or by "make install"
in the course of this installation, then find out where:
    which cdrskin 
Copy your standalone binary to exactly the address which you get as reply.
E.g.:

    cp cdrskin/cdrskin /usr/bin/cdrskin

Check the version timestamps of the globally installed binary
    cdrskin -version

It is not necessary for the standalone cdrskin binary to have libburn
installed, since it incorporates the necessary libburn parts at compile time.
It will not collide with an installed version of libburn either.
But libpthread must be installed on the system and glibc has to match. (See
below for a way to create a totally static linked binary.)

To install the man page, you may do: echo $MANPATH and choose one of the
listed directories to copy the man-page under its ./man1 directory. Like:
    cp cdrskin/cdrskin.1 /usr/share/man/man1/cdrskin.1

Note: The content of the cdrskin tarball is essentially the complete libburn
      of the same version number. You may thus perform above steps in a local
      SVN copy of libburn or in a unpacked libburn tarball as well.


                                    Usage

The user of cdrskin needs rw-permission for the CD burner device.
A list of rw-accessible drives can be obtained by

    cdrskin --devices

CD devices which offer no rw-permission are invisible to normal users.
The superuser should be able to see any usable drive and then set the
permissions as needed. If this hangs then there is a drive with
unexpected problems (locked, busy, broken, whatever). You might have to
guess the address of your (non-broken) burner by other means, then.
On Linux 2.4 this would be some /dev/sgN and on 2.6. some /dev/srM or /dev/hdX.

The output of  cdrskin --devices  might look like

    0  dev='/dev/sr0'  rwrwr- :  '_NEC'  'DVD_RW ND-4570A'
    1  dev='/dev/sr1'  rwrw-- :  'HL-DT-ST'  'DVDRAM GSA-4082B'

On Linux, full and insecure enabling of both for everybody would look like
    chmod a+rw /dev/sr0 /dev/hda
This is equivalent to the traditional setup chmod a+x,u+s cdrecord.

On FreeBSD, device rw-permissions are to be set in /etc/devfs.rules.
On Solaris, pfexec privileges may be restricted to "basic,sys_devices".
On NetBSD, rw-permission may be granted by chmod a+rw /dev/rcd?d.
See below "System Dependend Drive Permission Examples".

I strongly discourage to run cdrskin with setuid root or via sudo !
It is not checked for the necessary degree of hacker safety.
Better consider to grant the necessary permissions to group "floppy"
and to add users to it.


A behavioral conflict is known between any burn software and demons like hald
which probe CD drives. This can spoil burn runs for CD-R or CD-RW.
You may have to keep your hald away from the drive. See for example
   http://www.freebsd.org/gnome/docs/halfaq.html


Helpful with Linux kernel 2.4 is a special SCSI feature:
It is possible to address a scsi(-emulated) drive via associated device files
which are not listed by option --devices but point to the same SCSI addresses
as listed device files. This addressing via e.g. /dev/sr0 or /dev/scd1 is
compatible with generic read programs like dd and with write program growisofs.
For finding /dev/sg1 from /dev/sr0, the program needs rw-access to both files.


                                Usage examples 

For options and recordable media classes see 
    man 1 cdrskin

Get an overview of cdrecord style addresses of available devices
    cdrskin -scanbus 
    cdrskin dev=ATA -scanbus 
    cdrskin --devices

Adresses reported with dev=ATA need prefix "ATA:". Address examples:
    dev=0,1,0  dev=ATA:1,0,0  dev=/dev/sg1  dev=/dev/hdc  dev=/dev/sr0
See also "Drive Addressing" below.

Obtain some info about the drive
    cdrskin dev=0,1,0 -checkdrive 

Obtain some info about the drive and the inserted media
    cdrskin dev=0,1,0 -atip -v -minfo

Prepare CD-RW or DVD-RW for re-use, DVD-RAM or BD-RE for first use
    cdrskin -v dev=/dev/sg1 blank=as_needed -eject

Format DVD-RW to avoid need for blanking before re-use
    cdrskin -v dev=0,1,0 blank=format_overwrite

De-format DVD-RW to make it capable of multi-session again
    cdrskin -v dev=/dev/sr0 blank=deformat_sequential

Burn image file  my_image.iso  to media
    cdrskin -v dev=0,1,0 speed=12 fs=8m driveropts=burnfree padsize=300k \
            -eject  my_image.iso 

Write multi-session to the same CD , DVD-R[W] or DVD+R[/DL]
    cdrskin dev=/dev/hdc padsize=300k -multi 1.iso
    cdrskin dev=/dev/hdc padsize=300k -multi 2.iso
    cdrskin dev=/dev/hdc padsize=300k -multi 3.iso
    cdrskin dev=/dev/hdc padsize=300k 4.iso

Get multi-session info for option -C of program mkisofs:
    c_values=$(cdrskin dev=/dev/hdc -msinfo 2>/dev/null)
    mkisofs ... -C "$c_values" ...

Burn a compressed afio archive to media on-the-fly
    find . | afio -oZ - | cdrskin -v dev=0,1,0 fs=32m speed=8 \
                                  driveropts=burnfree padsize=300k - 

Burn 6 audio tracks from files with different formats to CD (not to any DVD).
Anything except .wav or .au files has to be converted into raw format first.
See below "Audio CD" for specifications.
    ogg123 -d raw -f track01.cd /path/to/track1.ogg
    oggdec -R -o track02.cd /path/to/track2.ogg
    lame --decode -t /path/to/track3.mp3 track03.cd   
    madplay -o raw:track04.cd /path/to/track4.mp3
    mppdec --raw-le /path/to/track5.mpc track05.cd

    cdrskin -v dev=0,1,0 blank=fast -eject speed=48 -sao \
           -audio -swab track0[1-5].cd /path/to/track6.wav

Extract audio tracks and CD-TEXT from CD into directory /home/me/my_cd:
    mkdir /home/me/my_cd
    cdrskin -v dev=/dev/sr0 extract_audio_to=/home/me/my_cd \
            cdtext_to_v07t=/home/me/my_cd/cdtext.v07t


                                Restrictions

Several advanced CD related options of cdrecord are still unsupported.
See output of command
    cdrskin --list_ignored_options
If you have use cases for them, please report your wishes and expectations.

On the other hand, the capability of multi-session and of writing streams
of unpredicted length surpass the current DVD capabilities of cdrecord.


                           Inspiration and Standard

cdrskin combines the command line interface standard set by cdrecord with
libburn, which is a control software for optical drives according to standard
MMC-5. For particular CD legacy commands, standards MMC-3 and MMC-1 apply.

For the original meaning of cdrecord options see :
    man cdrecord 
    (http://cdrecord.berlios.de/old/private/man/cdrecord-2.0.html)
Do not bother Joerg Schilling with any cdrskin problems.
(Be cursed if you install cdrskin as "cdrecord" without clearly forwarding
 this "don't bother Joerg" demand.)

cdrskin does not contain any bytes copied from cdrecord's sources. Many bytes
have been copied from the message output of cdrecord runs, though. I am
thankful to Joerg Schilling for every single one of them.
I have the hope that Joerg feels more flattered than annoyed by cdrskin.

Many thanks to Andy Polyakov for his dvd+rw-tools
  http://fy.chalmers.se/~appro/linux/DVD+RW/tools
which provide me with examples and pointers into MMC specs for DVD writing.


                                 Startup Files

If not --no_rc is the first argument then cdrskin attempts on startup to read
arguments from the following three files:
  /etc/default/cdrskin
  /etc/opt/cdrskin/rc
  /etc/cdrskin/cdrskin.conf
  $HOME/.cdrskinrc
The files are read in the sequence given above.
Each readable line is treated as one single argument. No extra blanks.
A first character '#' marks a comment, empty lines are ignored.

Example content of a startup file:
# This is the default device
dev=0,1,0

# Some more options
fifo_start_at=0
fs=16m


                                  Audio CD

Lorenzo Taylor enabled option -audio in cdrskin (thanks !) and reports neat
results with audio data files which are :
  headerless PCM (i.e. uncompressed)
  44100 Hz sampling rate 
  16 bits per sample
  stereo (2 channels)
  little-endian byte order with option -swab, or big-endian without -swab

Files with name extension .wav get examined wether they are in Microsoft WAVE
format with above parameters and eventually get extracted by cdrskin itself.
In the same way files with name extension .au get examined wether they are
in SUN's audio format. For both formats, track format -audio and eventual
endianness option -swab are enabled automatically.

Any other formats are to be converted to format .wav with above parameters
or to be extracted as raw CD track data by commands like those given above
under "Usage examples". Those raw files need option -audio and in most cases 
option -swab to mark them as little-endian/Intel/LSB-first 16-bit data.
Incorrect endianness setting results in random noise on CD.

I myself am not into audio. So libburn-hackers@pykix.org might be the
best address for suggestions, requests and bug reports.


                          DVD+RW , DVD-RAM , BD-RE

These random access media get treated as blank media regardless wether they
hold data or not. Options -audio and -multi are not allowed. Only one track
is allowed. -toc does not return information about the media content.
Speed is counted in DVD units (i.e. 1x = 1,385,000 bytes/second) or BD units
(1x = 4,495,625 bytes/second). Currently there is no difference between -sao
and -tao. If ever, then -tao will be the mode which preserves the current
behavior.

BD-RE media need formatting before first use. cdrskin option "blank=as_needed"
recognizes unformatted BD-RE and applies a lengthy formatting run.

During write operations DVD-RAM and BD-RE automatically apply Defect
Management. This usually slows them down to half nominal speed. If drive
and media produce flawless results anyway, then one can try to reach full
nominal speed by option "stream_recording=on".
In this case bad blocks are not detected during write and not even previously
known bad blocks are avoided. So you have to make your own readability tests
and go back to half speed as soon as the first read errors show up.
Instead of "on" one may also set a start address for stream recording.
Like "stream_recording=100m". This will write slowly to the first 100 MB of
the media and accelerate when writing to higher addresses.

Option --grow_overwriteable_iso allows -multi (although unneeded), enables
-msinfo and -toc, and makes blank=fast an invalidator for ISO filesystems
on overwriteable media.

Initial session (equivalent to growisofs -Z): 
  mkisofs ... | cdrskin --grow_overwriteable_iso blank=fast ...

Add-on session (equivalent to growisofs -M):
  cparms=$(cdrskin dev=/dev/sr0 --grow_overwriteable_iso -msinfo)
  mkisofs -C "$cparms" -M /dev/sr0 ... | \
    cdrskin dev=/dev/sr0 --grow_overwriteable_iso ... -


                            DVD-RW , DVD-R , DVD-R DL

DVD-RW are usable if formatted to state "Restricted Overwrite" or if in state
"Sequential Recording". DVD-R are always in sequential state. DVD-R DL are
always sequential and incapable of multi-session.

"Sequential" is the state of unused media and of media previously blanked
or written by cdrecord. dvd+rw-format -blank can also achieve this state.
The according cdrskin option is blank=deformat_sequential .
If "Incremental Streaming" is available, then sequential media are capable
of multi-session like CD-R[W]. (But not capable of -audio recording.)
This means they need option -multi to stay appendable, need to be blanked
to be writeable from start, return useable info with -toc and -msinfo,
eventually perform appending automatically.
Without Incremental Streaming offered by the drive, only write mode DAO is
available with sequential DVD-R[W]. It only works with blank media, allows only
one single track, no -multi, and demands a fixely predicted track size.
(growisofs uses it with DVD-R[W] if option -dvd-compat is given.)
 
Overwriteable DVD-RW behave much like DVD+RW. "Restricted" refers only to the
granularity of random access and block size which have always to be aligned to
full 32 kB. Sequential DVD-RW are converted into overwriteable DVD-RW by
  cdrskin dev=... -v blank=format_overwrite
(Command  dvd+rw-format -force  can achieve Restricted Overwrite, too.)

Formatting or first use of freshly formatted DVD-RW can produce unusual noises
from the drive and last several minutes. Depending on mutual compatibility of
drive and media, formatting can yield unusable media. It seems that those die
too on blanking by cdrecord, dvd+rw-format or cdrskin. Perils of DVD-RW.

There are three DVD-RW formatting variants with cdrskin currently:

blank=format_overwrite  uses "DVD-RW Quick" formatting (MMC-type 15h)
and writes a first session of 128 MiB. This leads to media which are expandable
and random addressable by cdrskin.

blank=format_overwrite_quickest  uses "DVD-RW Quick" formatting (type 15h) too,
but leaves the media in "intermediate" state. In the first session of writing
one may only write sequentially to such a DVD. After that, it gets random
addressable by cdrskin. DVD-ROM drives might show ill behavior with them.

blank=format_overwrite_full  uses preferably "Full Format" (type 00h).
This formatting lasts as long as writing a full DVD. It includes writing of
lead-out which is said to be good for DVD ROM compatibility. 

De-formatting options are available to make overwriteable DVD-RW sequential:

blank=deformat_sequential  performs thorough blanking of all states of DVD-RW.
blank=all and blank=fast perform the same thorough blanking, but refuse to do
this with overwriteable DVD-RW, thus preserving their formatting. The specs
allow minimal blanking but the resulting media on my drives offer no 
Incremental Streaming afterwards. So blank=fast will do full blanking. 

blank=deformat_sequential_quickest   is faster but might yield DAO-only media.


                           DVD+R , DVD+R DL , BD-R

From the view of cdrskin they behave much like DVD-R. Each track gets wrapped
into an own session, though.

DVD+R DL appear as extra large DVD+R. cdrskin does not allow to set the address
of the layer break where a reading drive might show some delay while switching
between both media layers.

BD-R are sold unformatted blank. If used without initial formatting then the
drive is supposed to format them to maximum payload size with no Defect
Management (see also above with BD-RE).
If Defect Management is desired then BD-R need to be formatted before the
first attempt to write a session to them.
blank=format_if_needed    will detect the situation and eventually apply
                          default sized Defect Management formatting.
blank=format_defectmgt_*  will apply non-default parameters to formatting.


                              Emulated Drives

cdrskin can use filesystem objects as emulated drives. Regular files or block
devices appear similar to DVD-RAM. Other file types resemble blank DVD-R.
Necessary precondition is option --allow_emulated_drives which is not accepted
if cdrskin took another user identity because of the setuid bit of its access
permissions.
Addresses of emulated drives begin with prefix "stdio:". E.g.
  dev=stdio:/tmp/my_pseudo_drive

For safety reasons the superuser is only allowed to use /dev/null as emulated
drive. See man page section FILES for a way to lift that ban.


------------------------------------------------------------------------------

                        Special compilation variations

All following options of ./configure and cdrskin/compile_cdrskin.sh are
combinable. After runs of ./configure do as next:
    make clean ; make

In some situations Linux may deliver a better write performance to drives if
the track input is read with O_DIRECT (see man 2 open). The API call
burn_os_open_track_src() and the input readers of cdrskin and libburn fifo
can be told to use this peculiar read mode by:
    --enable-track-src-odirect

But often cdrskin option dvd_obs=64k will yield even better performance in
such a situation. 64k can be made default at compile time by 
    cdrskin/compile_cdrskin.sh -dvd_obs_64k
It can also be enabled at configure time by
    ./configure ... --enable-dvd-obs-64k ...

Alternatively the transport of SCSI commands can be done via libcdio-0.83.
You may install it and re-run libburn's ./configure with option
    --enable-libcdio
Add option
    -use_libcdio
to your run of cdrskin/compile_cdrskin.sh .

You may get a (super fat) statically linked binary by :
    cdrskin/compile_cdrskin.sh -static
if your system supports static linking, at all. This will not help with kernels
which do not properly support the necessary low-level interfaces chosen by
your compile-time libraries.

A size reduced but fully functional binary may be produced by 
    cdrskin/compile_cdrskin.sh -do_strip

An extra lean binary with reduced capabilities is created by
    cdrskin/compile_cdrskin.sh -do_diet -do_strip
It will not read startup files, will abort on option  dev_translation= ,
will not have a fifo buffer, and will not be able to put out help texts or
debugging messages.


Linux only:

libburn tries to avoid a collision with udev's drive examination by waiting
0.1 seconds before opening the device file for a longer time, after udev
might have been alarmed by drive scanning activities.
The waiting time can be set at ./configure time with microsecond granularity.
E.g. 2 seconds:
  CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=2000000"
  ./configure ...options...
Waiting can be disabled by zero waiting time:
  CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=0"
Alternatively, libburn can try to be nice by opening the device file,
closing it immediately, waiting, and only then opening it for real:
  CFLAGS="$CFLAGS -DLibburn_udev_extra_open_cyclE -DLibburn_udev_wait_useC=500000"

------------------------------------------------------------------------------

                  System Dependend Drive Permission Examples

Accessing the optical drives requires privileges which usually are granted
only to the superuser. Linux, FreeBSD, Solaris, NetBSD, offer quite different
approaches for avoiding the need for unrestricted privileges.

First check whether some friendly system setting already allows you to
access the drives as normal user:
  cdrskin --devices
Those drives of which you see address and type strings are already usable.

If there remain drives invisible which the superuser can see by the same
command, then the following examples might help:

--------------- 
On all systems:
--------------- 
Add the authorized users of CD drives to group "floppy" in /etc/group.
If missing: create this group.
Changes to /etc/group often only affect new login sessions. So log out and in
before making the first tests.

---------
On Linux:
---------
Allow rw-access to the drives
  chgrp floppy /dev/sr0 /dev/sr1
  chmod g+rw   /dev/sr0 /dev/sr1
It might be necessary to perform chgrp and chmod after each reboot or to
edit distro dependent device configuration files for permanent settings.

-----------
On FreeBSD:
-----------
Edit /etc/devfs.rules and make sure to have these lines
  [localrules=10]
  add path 'acd*' mode 0664 group floppy
  add path 'cd*' mode 0664 group floppy
  add path 'pass*' mode 0664 group floppy
  add path 'xpt*' mode 0664 group floppy
  [localrules=5]
  add path 'pass*' mode 0664 group floppy
  add path 'cd*' mode 0664 group floppy
  add path 'xpt*' mode 0664 group floppy
  add path 'acd*' mode 0664 group floppy

Edit /etc/rc.conf and add the following line if missing
  devfs_system_ruleset="localrules"

This gets into effect by reboot or by command
  /etc/rc.d/devfs start

-----------
On Solaris:
-----------
Run cdrskin by
  pfexec cdrskin ...arguments...

The following settings will make pfexec keep original UID and EUID and prevent
most superuser powers. Be aware that you still can manipulate all device files
if you have the file permissions for that.
Full root privileges for cdrskin can then be acquired only by command su.

Edit /etc/security/exec_attr and add this line to the other "Media Backup"
lines:
  Media Backup:solaris:cmd:::/usr/local/bin/cdrskin:privs=basic,sys_devices
Edit /etc/user_attr and add profile "Media Backup" to the user's line:
  thomas::::profiles=Media Backup,Primary Administrator;roles=root
See also man privileges, man exec_attr, man user_attr.

Then allow the group r-access to the drives
  pfexec chgrp floppy /dev/rdsk/c3t0d0s2 /dev/rdsk/c4t0d0s2
  pfexec chmod g+r    /dev/rdsk/c3t0d0s2 /dev/rdsk/c4t0d0s2
The last two commands have to be executed after each boot. I do not know
the relevant device configuration files yet.

----------
On NetBSD:
----------
Allow rw-access to the drives
  chgrp floppy /dev/rcd[01]d
  chmod g+rw   /dev/rcd[01]d

------------------------------------------------------------------------------
                      Project aspects and legal stuff
------------------------------------------------------------------------------

Important Disclaimer :

This software is provided as is. There is no warranty implied and no
protection against possible damages. You use this on your own risk.
Don't blame me or other authors of libburn if anything goes wrong.

Actually, in case of severe trouble, nearly always the drive and the media
are the cause. Any mistake of the burn program is supposed to be caught
by the drive's firmware and to lead to mere misburns.
The worst mishaps which hit the author imposed the need to reboot the
system because of drives gnawing endlessly on ill media. Permanent hardware
damage did not occur in 13 years of development. But one never knows ...

------------------------------------------------------------------------------

Interested users are invited to participate in the development of cdrskin.
Contact: scdbackup@gmx.net or libburn-hackers@pykix.org .
We will keep copyright narrow but will of course acknowledge valuable
contributions in a due way.

------------------------------------------------------------------------------

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2 or later
    as published by the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

------------------------------------------------------------------------------
Based on and sub project of:
libburnia-project.org
By Mario Danic <mario.danic@gmail.com> and Thomas Schmitt <scdbackup@gmx.net>
Copyright (C) 2006-2023 Mario Danic, Thomas Schmitt

libburnia-project.org is inspired by and in other components still containing
parts of
Libburn. By Derek Foreman <derek@signalmarketing.com> and
            Ben Jansens <xor@orodu.net>
Copyright (C) 2002-2006  Derek Foreman and Ben Jansens
See toplevel README for an overview of the current copyright situation in
libburnia-project.org.