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

[Leslie Zhai]

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

--- Comment #11 from Leslie Zhai <lesliezhai at llvm.org.cn> ---
Hi Thomas,

Thanks for your help!

> "Writing speed: 5678 KB/s (4,1x)" obviously implies the speed factor
> for DVD of 1385 kB/s, rather than the factor of 4495 kB/s of BD.
> As BD speed 5678 kB/s would be about 1.3x.
> It is not clear which of both numbers is the computed one.
> Combined with the growisofs message
>   /dev/sr0: "Current Write Speed" is 4.1x4390KBps.
> i'd expect that 5678 is wrong and should be about 18500.
> (4390 KiB/s = 4495.36 kB/s.)
Yes, original GrowisofsHandler only considered about DVD, so I simply added
setMediaType for it to consider about Device::SPEED_FACTOR_BD too
https://github.com/KDE/k3b/blob/master/libk3b/projects/k3bgrowisofshandler.cpp#L177


> 
> "Estimated writing speed: 4046 KB/s (0,9x)" on the other hand is
> converted correctly.
> 
> One may ask the drive and inserted medium for its announced speed 
> values by this shell command:
> 
>   dvd+rw-mediainfo /dev/sr0
> 
> A PHILIP/R04 BD-R medium in ASUS BW-16D1HT drive reports
>   Write Speed #0:        8.0x4495=35968KB/s
>   Write Speed #1:        6.0x4495=26976KB/s
>   Write Speed #2:        4.0x4495=17984KB/s
> 
> The value "4.1x" reported by K3B could be really "4.0x" if K3B
> misunderstands 17984 kB/s as 17984 KiB/s (17984*1.024/4495 = 4.0969).
> 
> One should check K3B for such 1024 = 1000 mistakes. SCSI/MMC always
> reports and expects SI compliant kB/s. I.e. "k" = 1000, not 1024.
> This applies to the output of dvd+rw-mediainfo and to the reply of
> SCSI command GET PERFORMANCE.
> 
> 
> If i shall guess, then "Writing speed" is what K3B asks growisofs
> to use by option "-speed=4", and "Estimated writing speed" would be
Yes! in the K3b::GrowisofsWriter::prepareProcess()
https://github.com/KDE/k3b/blob/master/libk3b/projects/k3bgrowisofswriter.cpp#L291


Regards,
Leslie Zhai

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