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View Full Version : DCP looks a bit muddy in some areas - Bluray does not - what's wrong?



gmfb
06-29-2014, 02:10 AM
Hi,

I did a DCP with openDCP for a festival, but when playing on my computer it sometimes looks a bit muddy - the bluray of the same film looks cleaner. Is this because I'm playing that DCP on my computer in the wrong colour space? I even converted the TIFFs into JPG2000 with the highest rate - or is there anything gone wrong?

Suppose the festival won't have the time to pick out the better looking copy (bluray vs DCP) and I don't have access to a cinema to check the DCP under real-world-conditions.

Any advice (except of submitting just the bluray)?

Thank you!!

cheers,
Thomas

WhiteRabbit
06-29-2014, 03:05 AM
gmfb, my understanding is that your DCP is XYZ-colorspace. Your computer being RGB requires a player that will playback with an XYZ-colorspace to RGB-colourspace transform. I have not researched this for a while. Pending someone providing you with the appropriate advice, see if you can find a free player that will convert XYZ to RGB colorspace, so that it looks closer to normal than viewing XYZ-colorspace material in RGB environment.

gmfb
06-29-2014, 04:08 AM
Thanks WhiteRabbit,

I'm using the demo of Neo DCP-player, the colours look actually alright - so maybe the colourspace-transformation does cause taht muddiness...

WhiteRabbit
06-29-2014, 05:31 AM
gmfb, yes, I am sure there will be differences between the encoding software apps and the various players for playback. You may need to test it at a certified post house or try and find a smaller independent cinema with digital projection system and work out a deal to have a test screening? Otherwise, perhaps try and test the DCP at the festival prior to opening, if that is possible, and have your blu-ray ready in the other hand.

As for the whole colour consistency issue, I tried to use a Premiere plugin that renders direct to JPG2000 in XYZ colourspace. I found that their colour was not consistent with those generate from the TIF image sequence processed by open-DCP into the JPG2000 sequence output in XYZ in preparation of the MXF processing stage. Not sure which was correct, if any at all, hehe. Hopefully someone experienced with this process and with open-DCP can solve your question.

gmfb
06-29-2014, 05:45 AM
Thanks WhiteRabbit,

oh well, will try and see if I can test it somewhere!

tmeiczin
06-29-2014, 04:42 PM
If you try to view an XYZ image directly on your computer, it will look desaturated, greenish and lack detail. It is not a 1:1 conversion between XYZ and RGB, but rather X, Y, and Z are varying combination of the RGB values. In addition, the conversion when done with OpenDCP accounts for destination being a digital cinema projector. Some of the DCP players do a decent job converting back in to RGB, but you may see slight variations in color if you use a image comparison tool. You also need to account for what your source is - sRGB or REC709 or you will also get different results.

You should not use the full bandwidth value of 250mb/s for 2K@24fps as it will just result in unnecessarily large images. You can easily use 125mb/s and I typically use 75mb/s and sometimes even 50mb/s with no visually noticeable issues. As you increase framerate, 3D, or jump to 4K, then you need to start increase the bandwidth value.

gmfb
06-29-2014, 07:12 PM
Thanks tmeiczin,

I did a test run with the demo of NeoDCP Player, which seems to convert the colour space when playing. The thing I noticed looking worse than in the original prores-files or the bluray-disc is e.g. some leaves in the wind, they really look like badly compressed h264, otherwise the quality was about equal.
As I have to deliver today, I'll tell the cinema to use the bluray if they can't test the DCP beforehand.

tmeiczin
06-29-2014, 07:17 PM
Was the original source 16-bit and if so, did you export the as 16-bit? Did you scale the images at all?

gmfb
07-03-2014, 02:52 AM
Thanks tmeiczin,

the original material was 10bit Prores, I had the project set to 1920x1080 for the TIFF-export, so the 2k-DCP should just have added some pixel w/o upscaling.
Meanwhile I had to submit the DCP and the cinema reported back it played well on their system, which doesn't mean it looks great, but I've given up here, I'll just wait and see then. Maybe I was a bit too picxky about it and all will be fine.

WhiteRabbit
07-03-2014, 03:44 AM
gmfb, please let us know how it looked projected, if you make it to the screening. Thanks.

Frank Glencairn
07-03-2014, 04:54 AM
You guys may want to check out DCP-o-Matic.

It's freeware, works pretty good for me, and accepts a ton of formats, not only tiff sequences.
You can also specify if your source footy is sRGB, 709 or something else - and it will take care of that during the conversion to the XYZ space.

Works on Win/Mac/Linux


http://dcpomatic.com/

Peter Arnold
07-04-2014, 03:45 PM
I completely agree with Frank here.

I DCP-o-Matic is used here on a weekly basis for the pre-show content in our local cinema.
And I also do DCP screenings of my films for my clients in that cinema.

DCP-o-Matic, although a little slow, works like a charm.

I usually export DNxHD 444 Quicktime Clips from my AVID Timeline, simply put them in DCP-o-Matic and hit render, that's all.
The results look great on the big screen.

Peter

gmfb
07-05-2014, 07:27 AM
Thanks a lot, Frank and Peter,

sounds awesome!!

gmfb
07-05-2014, 07:28 AM
gmfb, please let us know how it looked projected, if you make it to the screening. Thanks.

Ta, will do so. It's just around the corner!

WhiteRabbit
07-05-2014, 08:36 AM
Thanks, Frank for the o-Matic info.

Peter, I had discounted this app from initial skim reading of the specs, thinking it may only load in 8-bit MP4 like footage. Learning you are feeding DNxHD 444 is great. Looking to add CineForm soon, master some to 2K 444 and make a DCP master would be great, together with the usual 1080p 10 and 8 bit versions. I must try this one soon, thanks.

gmfb, great to hear you will sit in the cinema and see your skill and art on a big screen. I hope the colour is pleasing to you, based on a calibrated projection for your own future reference and notes to self what you may change for next time. I marvel at the developers of film and colour timing prints for look and how they coloured a few decades ago, while we can click a few buttons and have instant feedback on screen. Amazing.

gmfb
07-05-2014, 12:41 PM
gmfb, great to hear you will sit in the cinema and see your skill and art on a big screen. I hope the colour is pleasing to you, based on a calibrated projection for your own future reference and notes to self what you may change for next time. I marvel at the developers of film and colour timing prints for look and how they coloured a few decades ago, while we can click a few buttons and have instant feedback on screen. Amazing.


Thank you! The last time I sat in the same cinema at a festival I felt fatally ill as all the short films in the block where mine was screened had
fast cuts, women and guns in them (and my colours looked too bright as well...), so I'll see how it goes this time.

You're right, it's so easy today to get predictable and good results kind of instantly (at least the feedback is!).

gmfb
09-15-2014, 02:37 PM
So now I've seen my film on a "big" screen (well, not that big, maybe 4 meters width) with a crowd of 20 ... it looked better than the DCP did on my PC, thank god. But some shots revealed in that size that I didn't hit the focus 100 % but when the shots were good, they looked gorgeous
(the ones inside I lit with two soft boxes looked so crisp and clean) and the ambient sounds were terrific. And colours looked like expected.

So far I'm pleased but hope that more people show up in 10 days at my private premiere in a small bar-cinema here.