[k3b] [Bug 384443] [MATSHITA BD-MLT UJ240AS] It does not record its maximum speed

[Thomas Schmitt]

https://bugs.kde.org/show_bug.cgi?id=384443

Thomas Schmitt <scdbackup at gmx.net> changed:

           What    |Removed                     |Added
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                 CC|                            |scdbackup at gmx.net

--- Comment #2 from Thomas Schmitt <scdbackup at gmx.net> ---
Hi,

the low effective speed is not a bug but a feature of formatted BD-R
media. During writeing the freshly written blocks are read and compared
with the data which are still in the drive buffer. This frequent change
between writing and reading slows down overall speed. Especially if
reading is not very successful. I.e. very low effectiive speed indicates
a bad relation between drive and medium and announces failure to come soon.

  https://bugs.kde.org/attachment.cgi?id=107725
looks like good relation for 4x speed and mediocre for 6x speed.

You may ask the drive with an unused medium for the speed list by

  dvd+rw-mediainfo /dev/sr0

which will reply something like

   Write Speed #0:        8.0x4495=35968KB/s
   Write Speed #1:        6.0x4495=26976KB/s
   Write Speed #2:        4.0x4495=17984KB/s

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Defect management can be avoided on BD-R media by adding

  -use-the-force-luke=spare=none

to the list of extra options for growisofs. It will then skip formatting
the BD-R medium before writing begins.

In my olde Debian 8 K3B this would be:

  Pulldown menu: Settings
    Item: Configure K3B
      Side bar icon: Programs
        Tab: User Parameters 
          Line: growisofs
            Click at column: Parameters
              Write the text: -use-the-force-luke=spare=none

The BD-R will have full nominal capacity and will be burnt at increasing
speed up to reaching full nominal speed near the end.
Noise might be substantial.

On BD-RE it cannot be avoided to format the medium. Above option might or
might not lead to full speed. The medium will have nominal capacity.
The only way to bring BD-RE to full speed is the option

  stream_recording=on

of backend program cdrskin (or command -stream_recording of xorriso,
or burn option Stream Recording in Xfburn).

Have a nice day :)

Thomas

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