Guide to Unix/Explanations/Compact Discs

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Ripping CD audio[edit]

This copies the audio from a CD track to a file. With some drives (one without analog connections to the sound card) this is the only way to correctly play a file.

Granting permission to the user[edit]

First you should have read-and-write permission to the CD device. (You could become root to rip the CD, but then you would have to "chown" the file back to you.)

First look at your CD devices nodes. On *BSD, they are at /dev/cd* and /dev/rcd*. If they look like this:

$ ls -l /dev/cd*
brw-r--'---  1 root  operator    3,   0 Nov  1 16:26 /dev/cd0a
brw-r--'---  1 root  operator    3,   2 Nov  1 16:26 /dev/cd0c
brw-r--'---  1 root  operator    3,  16 Nov  1 16:26 /dev/cd1a
brw-r--'---  1 root  operator    3,  18 Nov  1 16:26 /dev/cd1c

Here, root needs to grant read and write permission to the user. We decide to add the users to group "wheel". Once they are in, we change the group of the devices and grant read and write permission to the group:

$ sudo chgrp wheel /dev/cd* /dev/rcd*
$ sudo chmod g+gw /dev/cd* /dev/rcd*
$ ls -l /dev/cd*
brw-rw--'--  1 root  wheel    3,   0 Nov  1 16:26 /dev/cd0a
brw-rw--'--  1 root  wheel    3,   2 Nov  1 16:26 /dev/cd0c
brw-rw--'--  1 root  wheel    3,  16 Nov  1 16:26 /dev/cd1a
brw-rw--'--  1 root  wheel    3,  18 Nov  1 16:26 /dev/cd1c

Ripping tracks[edit]

We must insert a CD before ripping the track.

Here, for example, we rip track 2 and store it in song.wav. Our ".wav" suffix is because that is the default format of cdparanoia. With a CD in:

$ cdparanoia 2 song37.wav

Eject a disc[edit]

Many systems provide an eject command.

$ eject cd0

Burn a disk[edit]

Scenario: put the contents of a directory called backup to CD.

Here we do the actual burn (and eject) as root. The user needs to have "sudo" access, but not any special access to the CD device node.

Create a disk image of the CD. We will call it burn.iso.

  • -R is ISO6990 Rock Ridge support
  • -r is Rock Ridge but with all files to root (usable on computers with different users)
  • -hfs indicates a hybrid ISO9660/HFS disk
$ mkisofs -o burn.iso -r -hfs backup
$ chmod a-w burn.iso

Mount it to check for validity. (NetBSD/OpenBSD)

$ sudo vnconfig /dev/svnd0c burn.iso
$ sudo mount -r -t cd9660 /dev/svnd0a /mnt
$ diff /mnt backup
$ echo $?
0
$ sudo umount /mnt
$ sudo vnconfig -u /dev/svnd0c

The filesystem is good though file is misleading:

$ file burn.iso
burn.iso: x86 boot sector, extended partition table

Insert a blank disk.

This is a test burn to demonstrate cdrecord -v.

$ sudo cdrecord -v -dummy dev=/dev/cd0c burn.iso
cdrecord: No write mode specified.
cdrecord: Assuming -tao mode.
cdrecord: Future versions of cdrecord may have different drive dependent defaults.
cdrecord: Continuing in 5 seconds...
Cdrecord-Clone 2.01 (--) Copyright (C) 1995-2004 Jörg Schilling
TOC Type: 1 = CD-ROM
scsidev: '/dev/cd0c'
devname: '/dev/cd0c'
scsibus: -2 target: -2 lun: -2
Using libscg version 'schily-0.8'.
SCSI buffer size: 61440
atapi: 0
Device type    : Removable CD-ROM
Version        : 0
Response Format: 2
Capabilities   :
Vendor_info    : 'MATSHITA'
Identifikation : 'CD-RW  CW-8123  '
Revision       : 'CA0T'
Device seems to be: Generic mmc2 DVD-ROM.
Current: 0x0009
Profile: 0x0010
Profile: 0x0008
Profile: 0x0009 (current)
Profile: 0x000A
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Driver flags   : MMC-2 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R
Drive buf size : 1731072 = 1690 KB
FIFO size      : 4194304 = 4096 KB
Track 01: data   114 MB
Total size:      130 MB (12:58.58) = 58394 sectors
Lout start:      131 MB (13:00/44) = 58394 sectors
Current Secsize: 2048
ATIP info from disk:
  Indicated writing power: 5 
  Is not unrestricted
  Is not erasable
  Disk sub type: Medium Type B, low Beta category (B-) (4)
  ATIP start of lead in:  -11834 (97:24/16)
  ATIP start of lead out: 359849 (79:59/74)
Disk type:    Short strategy type (Phthalocyanine or similar)
Manuf. index: 24
Manufacturer: Sony Corporation
Blocks total: 359849 Blocks current: 359849 Blocks remaining: 301455
Starting to write CD/DVD at speed 24 in dummy TAO mode for single session.
Last chance to quit, starting dummy write    0 seconds. Operation starts.
Waiting for reader process to fill input buffer ... input buffer ready.
BURN-Free is ON.
Turning BURN-Free off
Starting new track at sector: 0
Track 01:  114 of  114 MB written (fifo 100%) [buf  98%]   8.2x.
Track 01: Total bytes read/written: 119586816/119586816 (58392 sectors).
Writing  time:  102.275s
Average write speed   7.6x.
Min drive buffer fill was 98%
Fixating...
WARNING: Some drives don't like fixation in dummy mode.
Fixating time:   34.457s
cdrecord: fifo had 1947 puts and 1947 gets. 
cdrecord: fifo was 0 times empty and 1860 times full, min fill was 80%.
$ echo $?
0

An actual burn:

$ sudo cdrecord dev=/dev/cd0c burn.iso
Password:
cdrecord: No write mode specified.
cdrecord: Assuming -tao mode.
cdrecord: Future versions of cdrecord may have different drive dependent defaults.
cdrecord: Continuing in 5 seconds...
Cdrecord-Clone 2.01 (--) Copyright (C) 1995-2004 Jörg Schilling
scsidev: '/dev/cd0c'
devname: '/dev/cd0c'
scsibus: -2 target: -2 lun: -2
Using libscg version 'schily-0.8'.
Device type    : Removable CD-ROM
Version        : 0
Response Format: 2
Capabilities   :
Vendor_info    : 'MATSHITA'
Identifikation : 'CD-RW  CW-8123  '
Revision       : 'CA0T'
Device seems to be: Generic mmc2 DVD-ROM.
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Driver flags   : MMC-2 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R
Starting to write CD/DVD at speed 24 in real TAO mode for single session.
Last chance to quit, starting real write    0 seconds. Operation starts.
Track 01: Total bytes read/written: 119586816/119586816 (58392 sectors).
$ echo $?
0

We should eject the finished disk now. The OS or drive might not know that the disk now has a filesystem on it.

$ sudo eject cd0

If we reinsert the disk then we can mount/unmount it:

$ sudo mount /dev/cd0a /mnt
$ sudo umount /mnt