A careful reminder: We just experienced issues playing back a DCP on classic Doremi
servers (DCP-2000/DCP-2k4, using Dolphin boards). They are known to be picky if the j2k
data rate approaches the DCI spec limit of 250MBit/s. Yesterday I experienced playback
issues on a DCP-2k4 at a data rate of 230MBit/s. The same DCP had no issues on a Sony 515
and Barco server. I checked the DCP, unwrapping the individual J2K images, and confirmed
that very many frames hit exactly the 230MBit/s spec (about 1178kByte per frame). There
was not a single frame peaking beyond that data rate. Yet that Doremi showed false colors,
green flashes, and audio sync issues in certain parts of the movie. Techwise, the DCP was
perfectly okay.
I can only advise, if your DCP goes wide and you can not control the type of system it is
played on, restrict yourself to around 200MBit/s to be on the safe side. Believe me, you
can not see the difference between 200 and 250 MBit/s even on a big screen. J2K has a huge
safety margin before visual image degradation occurs.
Most (even very big budget) mainstream DCPs stay well below 200MBit/s.
The same data rate limits apply for 4k and 3D releases. You don't double or quadruple
the data rate for 4k or 3D!
Regards - Carsten
Am 04.11.2019 um 12:36 schrieb Clive Osbourne via DCPomatic:
Yes, I did Carl thank you, after I sent you the email
I was going through the default settings and doing some more research on the JPEG2000
bandwidth settings. Then I realized I was not making any adjustment to the JPEG2000
bandwidth for newly-encoded
data", thanks a lot Carl. All is good now, I made the adjustment for a new
trailer I'm working on "THE COURIER" and every thing turned out ok. I'm
getting a 2.46gb DCP now from the QuickTime file of 2.75gb, instead of the 1.68gb I got
before.
Keep up the good work and best wishes to you and the team.
My best regards,
Clive.
On Sun, Nov 3, 2019 at 1:50 PM Carl Hetherington <cth(a)carlh.net> wrote:
Hi Clive
Have you tried adjusting the control "JPEG2000 bandwidth for newly-encoded
data"
Kind regards,
Carl
On Sat, 2 Nov 2019, Clive Osbourne via DCPomatic wrote:
Hi Carl, hope all is well with you, I'm a
user of your product DCP-o-matic for two years now and I have to say that it's a very
good DCP creator and one of the best according to the reviews I've seen online. I use
it to create movie
trailers for our cinema here in Barbados. Though I usually receive links from our movie
Distributors to download their DCP trailer content for our screens, if there are any
unavailable content I will go to
HDtrailers.net or
Thedigitaltheater.com. and download the the content if available. These trailers which I
download from the two sites in the above have to be prepped for DCP export which I use the
DCP-o-matic DCP creator to finish the trailer.
DCP file size: ( Distributors content file size vs DCP-o-matic file size.)
My observation of file size that the trailer content downloaded via link from our
Distributors have a greater file size than any trailer content that I create using the
DCP-o-matic creator.
I understand that the Distributor's content are mastered in Dolby 5.1 and mixed in a
facility studio with 5.1 audio track stems and full 2k video content that is then exported
to DCP with very expensive DCP creator software like Easy
DCP and Wraptor DCP. but the trailer content download from
Thedigitaltheater.com that are
mastered in Dolby 5.1 are copies from the good content and then converted to MKV and MP4
files that are smaller in size because of the
compression of audio and video bit rates.
If I convert one of these compressed trailer files to DCP using The DCP-o-matic creator,
then compare it to one of the Distributors files (the exact trailer) there is always a
difference in the size of the output file.
Mastering in Adobe Premiere Pro and Audition:
I've experimented with creating 2048x858 2K & 1998x1080 2K QuickTime video files
in Premiere with maximum bit rates and bit depths for optimum picture quality, and have
extracting the 5.1 files from the compressed content with
Audition then export to 5.1 wav files. Then I create and export a 5.1 2k sequence file
that give me a 2.9gb or a 3.0gb file depending on the length of the trailer.
DCP-o-matic export:
After I have imported the sequence file that I have created in Premiere into DCP-o-matic
and make all the necessary adjustments then I make the DCP. After the DCP is finished, I
am seeing that the file existing in the content folder
is half the size of the sequence file. Example! [ imported sequence file = 3.0gb]
[exported DCP folder with ASSETMAP, cpl, j2c, pcm, pkl, VOLINDEX = 1.5gb.]
There is also a drop in resolutions in the exhibition of the trailer content although all
DCP contents are 2K.
(1) Is the compression rate set by default to 2gb alone for all contents that are
approximately 2 minutes 30 seconds?
(2) Or, is there something that I can do to maintain a maximum quality content and keep
my file size matching the imported file size? Thanks!
Best regards,
Clive.
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