Comment 2 for bug 1654392

Hi,

did you already try -speed=1 in order to get the lowest possible speed ?

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The growisofs function to set the speed
  set_speed_B6h
in
  https://sources.debian.net/src/dvd%2Brw-tools/7.1-11.1/growisofs_mmc.cpp/#L1090
is quite complicated. It inquires the drive for the list of available
write speeds and inquires the current write speed.

If a speed was selected by program option (i.e. speed_factor != 0.0) then
it looks for the smallest offered write speed and begins to divide and
multiply. Then it looks for the offered speed which is closest to the
calculated value.
This obviously goes a wrong path by yielding "16.4x1352KBps" rather than
"12.3x1352KBps". (The display computation divides the KB/s number of effective
speed by the KiB/s number of 1x DVD speed. It should rather divde by 1385.)

One would have to watch in set_speed_B6h() the life of variables
"speed_factor", "minv", "targetv", and "velocity", to find out what
exactly goes wrong.

Maybe the computations are even ok and the drive just does not obey.

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If you look for an alternative to growisofs, then consider cdrskin or
xorriso personality xorrecord, which are better suitable for DVD and BD
than wodim and also not dead yet. (I am their upstream developer. If they
cannot set the speed either then we'd have some chance to find out why.)

Have a nice day :)

Thomas