This is topic I forgot projectors could switch input resolutions on the fly... in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.


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Posted by William Kucharski (Member # 7246) on 06-24-2019, 02:41 AM:
 
I never noticed before Toy Story 4 that the included trailers were 2K, but the feature itself was 4K, e.g.:
Yeah, it's an obvious capability when you think of it (looking back, Late Night did this too), but it still caught me off-guard.
 
Posted by Marcel Birgelen (Member # 6801) on 06-24-2019, 05:35 AM:
 
Well, it's not so much switching resolution. Ever since we're stuck with fixed-pixel imagers, whether it is the LCD or OLED screen in front of you or the DLP, transmissive LCD or LCoS chip in the projector, those machines do nothing more than constantly running at their maximum resolution.

If you're running a 4K machine, 2K content simply gets doubled both vertically and horizontally. If you're running 4K DCI content on a 2K machine, the media block just renders the 2K component of the JPEG2K images in there.

Back in the days when CRTs (both screens and projectors) where still a thing, we had some real resolution switching going on.
 
Posted by Tom Bert (Member # 5719) on 06-24-2019, 09:08 AM:
 
Is Toy Story 4 distributed in 4K everywhere in US?
 
Posted by Jim Cassedy (Member # 4115) on 06-24-2019, 09:25 AM:
 
quote: Tom Bert
Is Toy Story 4 distributed in 4K everywhere in US?
I assume so. All of the drives I've encountered at 4 different venues
were all 4k. The Ingest Letters distributed in the US show all the various
2D/3D versions with all the assorted audio permutations as being 4K only.
The only version I don't see is one in Dolby Vision™
 
Posted by Sean McKinnon (Member # 612) on 06-24-2019, 04:24 PM:
 
Has anyone else seen issues of one frame of small colored horizontal lines at the end of a CPL when switching either frame rates or resolutions?
 
Posted by Bajsic Bojan (Member # 4928) on 06-26-2019, 10:18 AM:
 
on doremi dcp2000 w/ barco B, we get a black frame between when switching frame rate, sometimes it is accompanied by glitchy looking dots or lines, sometimes not. they are not very noticable and not a lot of them, usually redish or purple in color.

on doremi dcp2000 ims w/Barco S, we get the same, black frame, sometimes same kind of glitch.

on GDC sx2000 w/NEC NC2000 we got a maybe half second black pause when switching frame rates. no glitch observed.

don't think i saw any glitches when switching from 2k to 4k content, but we always have black pattern between, running in 2k mode.
 
Posted by Jim Cassedy (Member # 4115) on 06-26-2019, 02:35 PM:
 
Projector: NEC 2000C (2k)
Serverthingy: Dolby DSS-200
Sometimes I've noticed a small momentary light colored line flash near the
bottom of the screen when switching between 2K & 4k (actually it only happens
when switching from 2k to 4k content, and not the other way around, if my
memory is correct) But it's so quick, and visually on screen it's not much
worse than a splice passing through a film projector, so I don't loose too
much sleep over it, although on really high-profile screenings or press
events especially if there's a prominent director or producer present, I'll
usually quickly shove a piece of cardboard in front of the lens just long
enough to hide the flash, since it's a manual booth and I'm 'stuck' up there
anyway so I might as well earn my keep.
(and it's impossible to program a 1 or 2 frame douser open/close command)

And yet, in another screening room, with the identical equipment, but which
was installed about a year later, I can't ever recall seeing this effect happen.
The only technical difference between booths is that only one is equipped for 3D,
and I know there are sightly different software versions between the two booths.
 
Posted by Martin Brooks (Member # 1269) on 06-28-2019, 10:22 PM:
 
quote:
The only version I don't see is one in Dolby Vision™
It's playing at Dolby Vision screens in NYC. That doesn't guarantee that the DCP is Dolby Vision, but it usually means that it is. And it's on Dolby's list as being available in Dolby Vision.
 
Posted by Carsten Kurz (Member # 5396) on 06-29-2019, 05:13 AM:
 
In Europe (and other 25Hz/PAL countries), the DSS200 is known for causing green flashes when switching between 24/25 fps CPLs in an SPL. Bad luck if you have one of those old projectors with dead slow dowsers.

- Carsten
 
Posted by Sean McKinnon (Member # 612) on 06-29-2019, 08:51 AM:
 
I think Bajic hit the nail on the head as far as what I've seen with Barcos. I've heard some people say it's when switching color spaces or resolution but I agree that it seems to be frame rate but not all the time. Only certain prices of content show this. It can be a small issue at film festivals or other high profile events with mixed content.
 
Posted by Steve Guttag (Member # 268) on 06-29-2019, 09:42 AM:
 
Switching frame rate is always where glitches are going to come from.

Look at what is happening at the ICP (or equivalent) level. The moment the server changes frame rate, you are going to lose sync with the projector. Mind you, the server's mediablock can have its own issues changing frame rates too which can compound the issue.

Until both the server and projector are locked back on the same frequency, unpredictable things can happen. There can/are strategies to minimize it but they would be on the order of blanking the image during the transition and likely would involve adding latency (delay) so that in the event of a frame rate change, before the sync is lost, blank the image.

Changing resolution in a DCP should never cause a glitch. The server and projector already know what the resolution of the system is. If you have a 2K system (projector), it is ALWAYS in 2K mode. The server is always extracting the 2K portion of the image in the MXF file and that is what is going to the projector. Conversely, if you have a 4K projector, the server can either send everything as 4K (scale 2K to 4K via a simple 2X in both directions) or the same thing can happen in the projector. You never lose sync so no glitch. the worst that could happen is if the scaling process happens in a non-black frame you could see it pop.

Color changes should also never cause a glitch because again, they can happen pretty seamlessly on a CPL transition. There is never loss of sync.
 
Posted by Alan Gouger (Member # 543) on 06-29-2019, 02:07 PM:
 
If running a mix of 2k and 4k trailers ( Barco 4k with ICMP ) how do you program the needed scaling between trailers?
 
Posted by Steve Guttag (Member # 268) on 06-29-2019, 04:05 PM:
 
You don't. You're missing how DCPs are encoded. Every server and every projector can handle both 2K and 4K.

Since the ICMP handles the "ICP" functions too, it is its choice on where it wants to scale since it both ends of the equation. Either way, it is happening in the ICMP. If the ICMP is in a 2K projector, it will always output 2K regardless of source. If it is in 4K, it will always output 4K, regardless of source.

In fact, you have to go out of your way to get it to do anything else since it uses a special "auto" file in the PCF.
 
Posted by Sean McKinnon (Member # 612) on 06-29-2019, 08:35 PM:
 
So how would you handle a festival type situation or a shorts program with content in different frame rates? Re-encode everything?
 
Posted by Marcel Birgelen (Member # 6801) on 06-30-2019, 01:14 AM:
 
Why would you want to re-encode everything?

As long as you don't bring your DSS1000, most common framerates should be supported.
 
Posted by Carsten Kurz (Member # 5396) on 06-30-2019, 03:02 AM:
 
I know one festival that converts (no re-encode necessary strictly speaking) to a common frame-rate. Because in short-film programs, the green flashing of their DSS200 was bothering them so much. And of course we have loads of 25fps here.

- Carsten
 
Posted by Marcel Birgelen (Member # 6801) on 06-30-2019, 06:45 AM:
 
I guess the glitching is a result of improperly clearing frame buffers while switching to a different refresh rate, much like Steve already described. In a perfect world, it shouldn't happen either.

The DSS200 indeed shows some green flashes and sometimes some random garbage. I have some "stub" DCPs with only black in there and no sound in varying lengths in different framerates. You can put one of those in front of a movie and close the dowser while playing it, it will get rid of most of the glitches.

The Alchemy was also prone to some glitching while switching between framerates, with some random junk on screen. That seems to have been solved in more recent firmware updates.
 
Posted by Daniel Morez (Member # 5787) on 07-02-2019, 05:29 AM:
 
quote: Steve Guttag
Color changes should also never cause a glitch because again, they can happen pretty seamlessly on a CPL transition. There is never loss of sync.
Coming from being the feature post cinema world, Im curious in what scenarios does the Color change in a CPL based presentation? Are we talking non-XYZ Advertising/Independent content book ending XYZ feature content?
 
Posted by Sean McKinnon (Member # 612) on 07-02-2019, 07:41 AM:
 
Thanks guys. Btw this has been seen with Doremi DCP 2K4 servers with IMBs
 




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