I demand that Rikishi 42 may or may not have written...

> On 2008-07-06, Rahul <nospam@nospam.invalid> wrote:
>> I'm always confused by DVD terminology when buying media to write on.
>> There's DVD / DVD+R / DVD-R / DVDRW and I'm not even sure which more! Are
>> these all really distinct technologies and formats? Or are some subsets /
>> supersets of others? Or maybe its only backward compatibility issues?

> 1. DVD is a bit generic, not very precise. But you would probably use it
> for commercial video-DVD's. Video-DVD has a specific format/organisation,
> but can be written to DVD+r, DVD-R and DVD RW. A bit like you can buy audio
> CD's and write your own audio CD on a CD-ROM disc.
>
> 2. DVD-r. The latter is a 'in-between' format, taking elements from CD's
> and DVD's. It's less reliable, is slower to write, less standard.
>
> 3. DVD+r. The 'standard' DVD, writes faster then DVD-r, is more reliable.
>
> 4. DVD-RW. Much like the CD-RW, you can re-write it. Usually a bit slower.

I've had problems with DVD-RW, but that was a few years ago and I've not
touched DVD-* since.

5. DVD+RW. Doesn't need to be blanked before rewriting; is good for random
access (packet writing).

6. DVD+R DL (dual layer).

I have one drive (read-only) which won't recognise these (at least the ones
that I've tried); a writer which has problems at around the layer-change
point (at least when reading back); and a laptop DVD drive which has no
problems whatsoever with what I've tested.

>> What's the best way to figure out what format my Laptop supports? Do they
>> have varied sizes? Does it matter whether I'm writing data or movies
>> etc.? I faintly remember there being lead-in / lead-out issues....

> In reading, any DVD reader should be able to read discs that are DVD-r and
> DVD-RW. Today's writers should be able to write all, too. some older ones
> could not use DVD+r.

Anything made within the last few years should cope with +R, +RW, +R DL, -R,
-RW. Probably -RAM too.

The contents of /proc/sys/dev/cdrom/info may help, but it's not exhaustive.

>> I've never faced the problem that I bought some commercial movie etc. on
>> a DVD and my Dell Laptop ( Inspirion E1505)'s inbuilt DVD reader /writer
>> couldn't read it. Its a dual boot so are there any Linux-vs-Win issues
>> too?

> Reading a commercial disc won't be a problem, you drive can do it. Reading
> the movie on the disc is another matter. You need a video-DVD player
> software. They exist for both Windows and Linux, of course.

regionset and libdvdcss2 help here. If you can, set the drive to region-free
(regionset allows 0 despite asking for a number between 1 and 8); else set it
to the correct region for your location.

>> Are these distinctions only relevant when writing disks at home as
>> opposed to commercially stamped disks? Or maybe when reading on hardware
>> other than "computers" (etc. DVD players etc.)

> Recent computers should be able to rad them all. Home DVD players can read
> commercial disks, and usually DVD-r and DVD+r. The support of DVD-RW is not
> universal.

DVD+RW should be fine. As always, careful handling helps; I'm seeing
roughly-handled discs failing early...

[snip]
--
| Darren Salt | linux or ds at | nr. Ashington, | Toon
| RISC OS, Linux | youmustbejoking,demon,co,uk | Northumberland | Army
| + Use more efficient products. Use less. BE MORE ENERGY EFFICIENT.

I'm not nearly as think as you confused I am.