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