What is the capacity of a BD-R disk really?

Tom Horsley horsley1953 at gmail.com
Sat Nov 26 15:38:21 UTC 2011


On Sat, 26 Nov 2011 15:15:29 +0000 (UTC)
Andre Robatino wrote:

> so
> if the container says "25 GB", that means 25*1000^3 bytes

Yea, that much I knew, but the best info I've found so
far is here:

http://www.hughsnews.ca/faqs/authoritative-blu-ray-disc-bd-faq/9-disc-capacity#9.2

and even it gets really fuzzy. Some variable amount of
overhead required for "defect management", and also
overhead for the UDF filesystem itself.

That page also implies you need to round the file sizes
up to next multiple of 65536 bytes when computing how much
space it will take to write them (which k3b apparently
does not do in its estimates).

Even taking all that into account, the files I tried to
write should have fit, but didn't, so somewhere between
300MB and 1GB of extra space was required by something
(maybe "defect management"?).


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