Hi Carl,
I have received a video in AVI container, DV codec, so, pretty standard. However, it is anamorphic, so no square pixels. Various media players on my machine detect it properly as 16:9, but DCP-o-matic 1.76.7 detects it as 720x576 (1.25:1) and squeezes it when choosing 'no scale'. No big deal to correct this manually in the scaling options, but maybe you can fix that. Since the media players display it correctly, there must be a flag the DCP-o-matic currently ignores when analyzing it.
The same happens when importing 16:9 VOBs from e.g. DVDs.
Hmm, I understand that there is some interpretation necessary. DCP-o-matic first follows Default Scale To in prefs. While that is correct, and some options chosen have to result in wrong aspect ratio scaling, I think that at least the 'no scale/no stretch' options should follow the original content AR, if it is clearly indicated in the file metadata. At least the content description should indicate that the files is flagged 16:9/anamorphic.
Aside from what the fact that in this case I can create a proper upscaled video - there is no way I could create an unscaled version of this file with the correct aspect ratio. When I choose 16:9, it get's uprezz'd, when I choose unscaled, I get a square 720/576 in a flat frame, when I choose NoStretch, I get a square 1350x1080. There is no way I can assign a 16:9 reference to this file.
I think the proper way to handle this is to find a 16:9/non-square pixel flag in the file and act accordingly, that is, display it stretched and with a 16:9/anamorphic indication.
I think that fight for all necessary yet straightfordward arranging of scaling options will never end...
- Carsten
I just did a test with separate video/audio clips. Imported them, video source is 24fps. DCP-o-matic reports source and DCP will have same frame rate. No mention of audio. I then adjust the DCP frame rate to 25 fps. DCP-o-matic tells me that the frame rate will be adjusted to 25 fps. However, there is no indication what it will now do anything with the audio? I think we discussed this before shortly, but didn't come to a proper conclusion. With separate audio files, will DCP-o-matic simply assume that the separate audio has to be in sync to the chosen DCP frame rate? Because with a different frame rate for video, it could just as well resample the audio to 25 fps as well - but it needs to be instructed to do so - which includes that there is a frame rate/sampling rate relation established before and a change being notified.
The question is - with separate audio, how/where do you establish it's frame rate reference at first so that DCP-o-matic knows to what framerate the audio is referenced? With interleaved audio, this is clear, upon loading it, the audio/video timing reference is established, but with separate video and audio files?
Did I make my issue clear?
- Carsten
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.
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?
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?
_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?
Sorry for the barrage of last-minute queries. I hope someone may have
some pointers?
Many thanks,
Jim
---------- Forwarded message ----------
Date: Wed, 15 Oct 2014 14:47:14 +0100
From: A. R. Madabushi <armadabushi(a)gmail.com>
To: Carl Hetherington <cth(a)carlh.net>
Subject: Re: [DCP-o-matic] P3 to XYZ conversion matrix (fwd)
Hi Carl thanks for the info!
The film is currently a DPX sequence in Resolve that was rendered in P3 colour space already. My DCP program doesn’t allow me to passthrough the file as
is, without performing an XYZ transform…which means I just need to make sure the DCP output looks the same as the DPX sequence.
If I export TIFFs from Resolve with an XYZ LUT applied, the DCP program will end up doing it again - so that’s XYZ conversion done TWICE, which I want to
avoid.
I found this site:
http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
…and given the info Carsten sent through I could make it…IF I understood how to do this kind of maths!
If I can figure out the maths - I could make it work! So CLOSE!!!
On 15 Oct 2014, at 14:38, Carl Hetherington <cth(a)carlh.net> wrote:
---------- Forwarded message ----------
Date: Wed, 15 Oct 2014 15:03:08 +0200
From: Carsten Kurz <audiovisual(a)t-online.de>
To: DCP-o-matic carlh net <DCPomatic(a)carlh.net>
Subject: Re: [DCP-o-matic] P3 to XYZ conversion matrix
Maybe this helps in creating a matrix:
DCI-P3
Gamma 2.6
White point
x 0.314
y 0.351
Red
x 0.680
y 0.320
Green
x 0.265
y 0.690
Blue
x 0.150
y 0.060
From what I understand now, xyz is the storage format within the DCP, while P3 is the color space used by DCI projector itself. When a server
plays a DCP,
it transmits xyz to the projector. The projector will convert to and show P3.
In a grading situation with a projector connected directly to the grading workstation for realtime playout, the xyz conversion is omited and P3
is played
directly from the grading workstation into the projector. A DCI projector therefore needs at least two different input profiles - P3 1:1, or
xyz->P3.
Now if you say you have a file sitting in P3 color space - what does that mean? Is it the color space associated with the editing project, or
do you have a
file rendered out in P3 - if so, which container/codec?
- Carsten
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
I guess the intention of the 'Show DCP' menu entry under 'Jobs' ist to show the path/directory of the currently generated DCP? I think this never worked in the Mac version, or did it? Currently, it does nothing.
A lot of unexperienced users ask which of the various files and directories DCP-o-matic creates should be copied to the transfer drive. While this is essentially a training/knowledge problem, I think choosing 'Show DCP' should result in the display of the parent folder of the DCP directory, with the DCP folder selected/highlighted so it can be easily identified. It nearly works in the windows version ;-)
- Carsten
I just redid some benchmarks to find out if the new 12Bit processing causes any performance degradation. On two machines, Mac and Windows, 1.76.12 is even slightly faster than 1.69.
Carl, is the 12Bit processing always on, or only with content >8Bit?
- Carsten
Thanks Carl!On Nov 10, 2014 4:08 AM, Carl Hetherington <cth(a)carlh.net> wrote:
>
> On Sun, 2 Nov 2014, Sumit Guha wrote:
>
> > I like Carsten's idea of individual H/V sliders. Maybe you can have it as an user-selectable option so that one can choose to use it or not.
>
> OK, I've added that to the to-do list:
> http://carlh.net/mantis/view.php?id=425
>
> I guess if it's hidden behind a "custom scale" option it should be ok.
>
> Best,
> Carl
>
> _______________________________________________
> DCPomatic mailing list
> DCPomatic(a)carlh.net
> http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
I like Carsten's idea of individual H/V sliders. Maybe you can have it as an user-selectable option so that one can choose to use it or not.
Sumit
On Nov 2, 2014 9:46 AM, Carsten Kurz <audiovisual(a)t-online.de> wrote:
>
>
> Am 31.10.2014 um 00:36 schrieb Carl Hetherington:
>
> > As I said above... I had not anticipated the desire to have true
> > no-scale, to put a small image in the middle of a big screen...
>
>
> Yes, bit of a problem, how many 'creative' options do we want to add to the software - putting a picture into a black frame like this technically is letterboxing/pillarboxing, but not in a strict technical sense. Normally one would do that in an external editor.
>
> BTW - this is not only a problem with SD footage like from DVDs or DV-video - there are also HD-formats with non-square pixels, e.g. HD-DV/HDV is 1440/1080, and I just took a short test with my Sony digital camera set to MP4 format - it says '1080' in the camera menu, but in fact creates a 1440/1080 file with non-square pixels. DCP-o-matic states it is 1,33:1 and previews it squeezed.
> Now again, I can 'just' get it right in DCP-o-matic using the 16:9 option, but that is the only way to do it. Also - in this case I KNOW it is 16:9 and non-square pixels - what if people do not know it and/or the preview image doesn't give a clear visual indication?
>
> Personally I would love to have individual H/V scale sliders, but I don't think this is suitable for the general public ;-)
>
> I guess it would be best to make DCP-o-matic use an existing AR-flag. Then - checkbox or not..., in content tab, or prefs? I guess I would want to have this handled in content specific options, so a 'per file' setting.
> At some point it could become important with bitmap files as well, although they are usually easier to correct externally.
>
> I have seen quite a few files with non-square pixels WITHOUT a proper flag, but I have hardly ever seen a file with a 16:9 flag set wrongly, so I think the risc is small this will cause real harm. And I think most people would like to have DCP-o-matic show these common content types - DV/HDV, and 16:9 DVD with the correct aspect ratio after import immediately. Like my fellow projectionist does ;-)
>
> - Carsten
>
> _______________________________________________
> DCPomatic mailing list
> DCPomatic(a)carlh.net
> http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
Today I had to create a DCP without sound, that is, the minimum requirement would be 2ch, padded with silence.
I think DCP-o-matic has no formal way to do this - I can set channel count to 0 in DCP properties, but then I get a warning that my DCP contains no sound, that I guess means that no audio.mxf will be generated at all.
Same happens when I deselect the existing two audio channels in content audio tab. I think DCP-o.matic should be stricter, that is, if channel count is set to 0, it should create a 2-channel file padded with silence. Same if I deselect existing channels in an interleaved video/audio file. And it should force channel count to an even number of channels any time. Maybe for now, the easiest way is to limit the channel choices in the DCP tab to 2,4,6,8..., and if there is no audio, or it is deselected in the audio matrix, it should padd the channels chosen in DCP tab with silence.
Of couse, I could just use a very high negative gain, or map the existing audio to channels typically not used. But I think there should be a straighter way.
- Carsten
