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Thread: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

  1. #11
    Join Date
    Feb 2013
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    76

    Re: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

    Hi,

    > 2) Irrespective of the CD/DVD drive being used, Brasero when recording CDs
    > on recent ubuntu distros (1804 and 1604 tested) writes a bad block at the
    > end of the data. This doesn't happen with DVDs or CDs recorded on very old
    > systems (0710 and 1004 were tested).

    Hehe. That's another one of my favorite Linux bugs.
    It happens only with CD written with write type Track-At-Once (TAO) and
    further depends on the reader drive and on the Linux kernel version.

    Workaround would be to select Session-At-Once (SAO aka DAO) in Brasero.
    (If i only knew where the option is hidden.)

    If you use Xfburn instead of Brasero, make sure to have set "Write mode"
    to "SAO", not "TAO". The default "Auto" is supposed to choose SAO. But
    one never knows ...
    See the "Write mode" selection menu in the middle of
    http://www.tuxarena.com/static/scree...1/xfburn03.png

    TAO writes two non-data blocks (aka "Run-out") at the end of the CD track.
    Most drives tell the track size including those blocks when being asked
    by SCSI command READ CAPACITY. Those can trigger the Linux error, because
    Linux tries to read up to the announced last block.

    Modern Linux has some workaround which seems to help if the number of CD
    blocks is divisible by 2, but not with odd numbers.
    So we still see this problem frequently but often it also gets hidden by
    a friendly drive or the Linux attempt to work around.

    xorriso's -check_media assumes such a TAO end if the last two blocks of
    the CD track are not readable as data. Then it reports them separately
    as neither good nor bad ("0" instead of "+" or "-").
    Code:
    Media checks :        lba ,       size , quality
    Media region :          0 ,     157154 , + good
    Media region :     157154 ,          2 , 0 tao_end

    > This doesn't happen with xorriso which writes clean in every test I've done

    If you don't tell it to use TAO, then it will choose SAO if it knows
    the size of the data job in advance. Only image burning from a pipe
    will choose TAO and normally won't work with SAO. E.g.
    Code:
    tar czf - . | xorriso -as cdrecord -v dev=/dev/sr0 -waiti -eject -

    > 3) Xubuntu 18.04 recognises the bad block at the end of a CD read
    > (irrespective of application used) and sets the maximum speed to 4x
    > (600KB/s) so that the next program reads slowly.

    Ouchers ! That's stupid. Speed has nothing to do with read errors.
    The drive would slow down and retry on its own, if the block was
    marked as data block.

    In any case the slowdown should be revoked after the tray moved out
    for a potential media change.

    (I still think that Brasero slows down too. But with a 10x CD-RW or
    a 40x CD-R and maximum write speed this has not such a dramatic effect.)


    > That can be fixed by using
    > xorriso and cancelling it before the end of the disk.

    You need to wait with cancelling until the first message
    Code:
    xorriso : UPDATE : X of Y blocks read in Z s , N.NxC
    Else you risk that the SET CD SPEED command was not yet sent to the drive.

    The minimal remedy without cancelling would be
    Code:
    xorriso -outdev /dev/sr0 -read_speed max -check_media use=outdev max_lba=0 --
    Runtime 5 to 10 seconds without intervention. It stops as soon as it is
    safe for your purpose.


    > It's a great pity that xorriso is such a fantastic piece of software that it
    > is too complex for routine daily use by a numpty such as myself.

    There is also a complex GUI
    https://screenshots.debian.net/scree.../893/large.png

    You could download
    https://dev.lovelyhq.com/libburnia/l.../xorriso-tcltk
    give it x-permission, and run it by simply executing in a shell terminal while being in its
    dowload directory
    Code:
    ./xorriso-tcltk
    Click on "Help" to the upper right, and right-click on any GUI element
    in order to get a window with a help text.
    (Another terminal window with "man xorriso" is helpful to learn details
    about the mentioned xorriso commands.)


    > Question: are there any burners out there that have a simple GUI for
    > handling CDs and DVDs (similar functionality to Brasero) but which have
    > xorriso (or similar engine) as the back end?

    I tried to persuade Xfburn and K3B. But both projects have no maintainer
    who could make such a big change. Brasero is not even maintained enough
    to get the burn speed setter fixed.

    So i wrote xorriso-tctk as demo of a frontend program that cares for
    user interaction but leaves the job of composition and burn settings
    to xorriso. (6000 lines of Tcl code. About 3500 are comments and help
    texts. It was about a week of work.)

    Have a nice day

    Thomas
    Last edited by scdbackup; May 10th, 2019 at 12:26 PM. Reason: Mentioned the need for setting x-permissions to xorriso-tltk after download

  2. #12
    Join Date
    Nov 2007
    Beans
    21

    Smile Re: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

    Thomas, that's brill.
    Once upon a time (it may even have been in windows 3.1 when CDs were still quite a new thing) I'm sure Brasero had an option to write SAO and the default was TAO. There used to be lots of settings like buffer size and read-after-write checks etc.

    Xfburn seems to do the trick and it's usable as an every day pgm - even for an old sausage fingers like me! And even if I forget to set it to SAO, it seems to write clean CDs on Auto. Not tried DVDs but I'm making the assumption that that bit works OK but I will check in due course.

    I haven't tried your GUI yet but it's on the "to do" list. Right now I have a whole heap of CDs that need rewriting... 'twas ever thus!

    Tks again
    jg
    Last edited by lisati; May 12th, 2019 at 06:00 AM. Reason: Typo

  3. #13
    Join Date
    Nov 2007
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    21

    Re: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

    Interesting postscript ...

    Tried to recreate a Xubuntu 12.04.4 Live CD with a bad end block/run-out but the new image on repository has grown to 780MB - too big for a CD. So used Brasero to create an ISO from the bad CD (using 1:1 disk copy) and it asked to install cdrdao so it could write "disk at once", aka SAO. It then creates a .toc image file that cdrdao uses to burn disk-at-once. The result was clean, ie no bad block at the end. Unfortunately it still doesn't provide the option to burn regular CDs disk-at-once!

    jg

  4. #14
    Join Date
    Feb 2013
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    76

    Re: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

    Hi,

    > Xfburn seems to do the trick and it's usable as an every day pgm

    It's most obvious drawback is that cannot do multi-session.

    Brasero can "import" a medium which was "left open" in a previous burn run.
    It then can write an updated directory tree and new file data to the
    remaining free space on the medium.

    xorriso is able to do this for ISO 9660 filesystems even on DVD+RW, BD-RE,
    and formatted DVD-RW media, which do not support multi-session by hardware.
    (Commands -dev and -indev do this importing.)

    K3B is similarly capable by help of growisofs.

    > I'm sure Brasero had an option to write SAO and the default was TAO.
    > There used to be lots of settings like buffer size and
    > read-after-write checks etc.

    I started my outdated copy of Brasero. 3.11.4. It mistakes a DVD+RW for
    a DVD-RW and offers different burn options for it than for a blank CD-RW.
    No option for TAO-or-SAO to see with either of the media.
    (If it thinks it's a DVD-RW, then there should be the choice between
    DAO and Incremental write type.)

    A code search in Debian's repo gives me the impression that SAO is
    only enabled for audio CDs with CD-TEXT. Maybe there is also an opportunity
    to use wodim as interpreter of .toc or .cue files. They describe a SAO run.

    > cdrdao [...] disk-at-once

    cdrdao's disk-at-once is the same write type as SAO.
    (Actually Disk-At-Once is the term for DVD-R and unformatted DVD-RW.)

    Have a nice day

    Thomas

  5. #15
    Join Date
    Nov 2007
    Beans
    21

    Re: Optical Drive slow reading CDs - Dell XPS17 Xubuntu 18.04.2

    Hi, Thomas
    Yes the multi session thing is a pain, but not such a nuisance nowadays as it was 20 years ago when files were so much smaller. Most of my current CD usage is for start-up/recovery disks, music and sending stuff in the mail, none of which encounter the need for multi-session recording. In any case, I find USB sticks much more convenient for that sort of thing.
    I'm afraid I don't have any of my really old Brasero.exe files but I still have a CD with an early copy of "Burning Nero" from around 1996 according to the copyright - no version number quoted and as I don't run Win3.1 any more, I'm not about to install Wine in the hope I can launch it! DVDs hadn't been invented then, or if they had they weren't commercially available.
    I'm going to draw stumps at that.
    Tks again for your help and guidance.
    vbw
    jg

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