[k3b] [Bug 380064] [MATSHITA BD-MLT UJ240AS] Estimated writing speed: 4046 KB/s (0,9x)*?

[Thomas Schmitt]

https://bugs.kde.org/show_bug.cgi?id=380064

--- Comment #12 from Thomas Schmitt <scdbackup at gmx.net> ---
Hi,

the strange speed value 4.1x seems to stem from a 1024/1000 confusion
in growisofs.
growisofs_mmc.cpp has:

  #define BD_1X   4390    // 4495.5 * 1000 / 1024
  ...
        _1x = BD_1X;
  ...
      page2A = pull_page2A (cmd);
  ...
    hlen = 8 + (page2A[6]<<8|page2A[7]);

    unsigned char * const p = page2A + hlen;
  ...
    {   velocity = p[28]<<8|p[29];
  ...
        fprintf (stderr,"%s: \"Current Write Speed\" is %.1fx%dKBps.\n",
                        ioctl_device,velocity/(double)_1x,_1x);

Page 0x2A is the obsolete "CD/DVD Capabilities and Mechanical Status Page"
last mentioned in MMC-3. One can ask a drive to fill it out and return it.
Its bytes 28 and 29 then contain the "Current Write Speed Selected".
To my knowledge, all drives return this value as kB/sec. So growisofs
should divide it by 4495, not by 4390.

Not K3B's fault. growisofs needs a maintainer.


Have a nice day :)

Thomas

-- 
You are receiving this mail because:
You are the assignee for the bug.