22 Nov
2014
22 Nov
'14
1:10 a.m.
Hi Jim,
On Fri, 21 Nov 2014 20:55:57 +0000
Jim Dummett <j(a)dummett.org> wrote:
Hello all.
I'm doing tech on the London Short Film Festival which is January. We
are delivering all the films to cinemas on DCP this year (all 350 of
them) and will be using DCP-o-matic to use them.
We're holding a workshop tomorrow and Sunday where we're going to
train 100 film-makers on DCP-o-matic, and then guide them through the
process so that by the end of the weekend, they will hopefully all
have DCPs of their films.
That sounds fun!
I have a couple of last-minute questions that I would
very much
appreciate it if anyone would be able to help with.
_1. Encoding servers_
We have a network of 30 iMacs, all networked together with Gigabit
ethernet. We intend to run dcpomatic_server_cli on all of those, with
DCP-o-matic itself running on the laptops of the film-makers and
using the encoding servers to do the heavy lifting.
a. Will it work with 30 encoding servers?
It should. I haven't tested it with quite that many. A single master
can saturate a Gbit ethernet quite quickly (around 8 servers, or so) but
if you are talking about multiple masters with 30 servers it should be
ok.
Are you connecting the laptops with Gigabit cabled ethernet? Things
would be much slower if you relied on wireless, especially if you have
100 laptops all sharing the same channel.
b. What happens if two instances of DCP-o-matic try to
send jobs to
the encoding servers simultaneously? Is it first-come-first-served
and whoever submits their job first gets control of all the encoding
servers until their job is complete? Or do the encoding servers get
shared out between different jobs so multiple jobs can run
concurrently? Or, terror-of-terrors, will the whole thing crash?
In theory, each server should tell each master that it is available,
and then each master should send each server frames to encode. The
servers should share their power out amongst any masters which ask them
to do encoding work. In short: it should share out the encoding
servers so multiple jobs can run concurrently.
This has not been tested, though (by me, at least).
_2. Best version to use_
How stable is v1.76.13 likely to be? Or should we use v1.76.0?
I've been told that some issues with colour space conversion are
being resolved in recent test releases. Is v1.76.13 going to give a
better result in terms of colour than the 1.76stable?
The significant change in 1.76.13 wrt 1.76.0 is that 1.76.0 truncates
all its video to 24-bits-per-pixel RGB as part of the processing
chain. This is less than the 36-bits-per-pixel that DCP allows.
For stability, I would choose 1.76.0. On the other hand, I'm not aware
of any new bugs in 1.76.13. It depends on how likely your users are
to have source material in high bit depths.
Do let me know how you get on, and please feel free to impress upon
your film-makers that this mailing list (or the forum at
dcpomatic.com/forum) is the best place to come if they have any problems
with DCP-o-matic: if we know about them, we can try to fix them.
Best of luck!
Regards,
Carl