[sclug] Blu-Ray writing

[Daniel Craigie]

On 16 Jul 2012, at 23:57, Dickon Hood wrote:

> On Mon, Jul 16, 2012 at 22:10:46 +0100, Daniel Craigie wrote:
> 
> : The drive appears in /dev/ as multiple devices:
> : brw-rw----+ 1 root cdrom 11, 0 Jul  9 19:20 /dev/sr0
> 
> : lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/cdrom -> sr0
> : lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/cdrom1 -> sr0
> : lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/cdrw -> sr0
> : lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/cdrw1 -> sr0
> 
> It doesn't.  That's one device -- /dev/sr0 (AFAICT 'SCSI ROM') -- with
> some symlinks pointing to it for compatibility reasons.  Frankly, I'm
> surprised; I'd've expected cdrom0 instead of cdrom1 and similar, if they
> were to appear at all.  What distribution are you running?  I'm quite
> surprised you don't have a /dev/dvd too.

Woops!  That would be surprising, had I not forgotten about it in the first place:
lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/dvd -> sr0
lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/dvd1 -> sr0
lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/dvdrw -> sr0
lrwxrwxrwx 1 root root 3 Jul  9 19:20 /dev/dvdrw1 -> sr0

I'm running Debian GNU/Linux 6.0.5 (squeeze) on a Linux 2.6.32-5-686 i686 kernel.
> 
> : Am I correct to assume that the duplication of both the cdrom and cdrw
> : links reference the two layers of the disk as separate disks?
> 
> No.  I've never done this, but I'm going to assume that multi-layer discs
> are handled the same as they are on DVDs: one, contiguous logical set of
> sectors.  It's the only model that makes sense.

So you mean that the second layer is handled exclusively by the drive?
The software is just writing to a disk with a total capacity of 50GB?
> 
> : I have found sporadic info online regarding the actual process of
> : writing data to the disks.  I'm not sure if the existing dvd writing
> : software can cope with the amount of data that will be written to the
> : disks, I fear buffer overflows and don't fancy having to throw away
> : expensive & empty disks.
> 
> : Any advice greatly appreciated,
> 
> Again, it's a guess, but I would assume that something like libburn (use
> the cdrskin wrapper, or similar) will write something useful to it.  Most
> of the time, media of this sort tends to behave as the older generation
> did, so as to not confuse anything.
> 
> mkisofs used to be able to take a directory structure and produce a stream
> of objects from it, if you wanted something vaguely standard.  I'd
> probably do something like that, or possibly write a raw tar, if I'm just
> interested in getting the data to disc ASAP.
> 
> In short: try a DVD writer.  It'll probably do exactly what you want it
> to, and, for the price of a disc, is worth testing.  And report back here
> if it works -- I'm interested in similar myself, ta :-)

Thanks, which type of compression would you recommend for video files?
> 
> 
> Dickon Hood
> -- 
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