Re: Bug in growisofs: No write speed change possible for Philips DVDR824P
> INQUIRY: [PHILIPS ][DVDR824P ][P1.2]
>
> > > No matter what write speed value I select my DVD-burner always chooses
> > > the highest possible values. I am using dvd+rw-tools-5.17.4.8.6.
> > >
> > > I digged in the source and found that following the "GET PERFORMACE"
> > > request (growisofs_mmc.cpp:785) my drive only returns one possible speed
> > > value.
> > >
> > > If I hardcode a legal speedvalue like 2.4 in growisofs_mmc.cpp my drive
> > > uses that speed.
> >
> > Do you mean it accepts the command without signalling an error or do you
> > mean that it accepts the command *and* performs the recording at chosen
> > speed? Specification says that unit should accept *any* performance
> > value and then stick to closest one from the list returned by GET
> > PERFORMANCE.
>
> It accepts the command and writes at speed 2.4 while GET PERFORMANCE returns
> only 8.
This is odd... As far as I understand Philips 824 is result of
collaboration with Benq, but other derivatives, e.g. hp dvd400c, are
known to return more descriptors in reply to GET PERFORMANCE... Could
you test if dvd+rw-tools-5.16.x can control speed of your unit? It
should, because unlike 5.17, 5.16 [still] relies on Page 2A to pull the
list of supported velocities for currently mounted media.
In case you wonder why 5.17 favors GET PERFORMANCE over Page 2A (the one
used to contain recording velocities). In latest MMC specification Page
2A is declared as being "no longer recommended for use in multi-media
devices," while GET PERFORMANCE was mandatory for implementation since a
while ago. At the same time other units, most notably NEC derivatives,
were observed to report bogus descriptors through Page 2A, while other
units were observed to maintain same speed lists through *both* Page 2A
and GET PERFORMANCE command. But so far no unit was observed to report
sane descriptors in Page 2A and not provide copy of the table through
GET PERFORMANCE. This formed the ground for the decision to switch. And
your unit apparently breaks this assumption by *not* providing a
complete set of speed descriptors through GET PERFORMANCE command (as
you can observe in dvd+rw-mediainfo output: there is a number of "Write
Speed#N," but only one "Speed Descriptor#0."
What happens next? Verify that 5.16 works and if it does, stick to it
till further notice. Check for firmware update and if there is no any or
if it doesn't fix the problem, try to file bug report to Philips
claiming that the unit in question "fails to provide Type 3 data,
supported speed descriptors for currently mounted media, through GET
PERFORMANCE command." A.
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