HFR being interpreted as 3D - workaround?

[trwh]

Hi,

I've created a Flat 2K SMPTE DCP which is 50p so High Frame Rate (HFR), and I'm going to show it at 2 cinemas. The first cinema has a Barco DP4K projector and Dolby IMS3000 media server, and can display the Composition fine, but the second cinema is having problems with the colour, see the picture below.

The second cinema says they have an Osram XBO projector but when I Google that it seems they're referring to the lamp inside it, so I'm not sure which projector and media server they have.

I assume their equipment doesn't automatically recognise HFR and my guess is the 50p content is being interpreted as 3D with one eye magenta and one eye green. What do you folks think? If this is the case then the package has been delivered correctly and their projector and / or media server just needs to interpret the content as 2D. Is this an easy setting for them to change? Can you help me walk them through any config change necessary please?

Of course my fallback is to create a 25p DCP but the content does benefit from the high frame rate so I'd prefer to try to get 50p working first. It will also help the staff at the cinema understand how to handle HFR in future so a benefit all round.

Thanks in advance,

Tim

[StephW999]

small precision: 50 p 2D is not HFR. (HFR = 96/100/120 fps in 2D or 48/50/60fps in 3D).
this being so in the cinema the dcp 50p cannot be read correctly it is that the server is connected with an Hd-SDI connection. It is therefore impossible to read this DCP with this equipment. The solution is to do it in 25 fps.

[Carsten]

This is 'normal' behaviour for Doremi servers. They need to force the playlist to 2D, which is easy to do in cinelister. However, if they indicate their type of projector as 'OSRAM XBO', they may still have trouble finding that checkbox. sigh...



If this is a classic Doremi with HD-SDI, it may still not work in 50fps. In that case, it is actually a solution to play the 2D DCP as 3D, and set the projector to a 3D channel. The 3D channel/preset will then decode the proper colors. Depending on projector and firmware involved, this should work up to 60fps.

- Carsten

[trwh]

Hi Carsten,

Many thanks indeed for this, I’ll pass those fixes on to the cinema in question.

Fingers crossed!

Tim

[macuser]

Hello,

in my experience it could also be a problem with the selected colour space on the beamer.
You will have the same effect with the Doremi Server on a Christie beamer. With 50 fps you should use a preset with YCbCr colour space instead of X'Y'Z' colour space!

Kind regards
Max

[trwh]

Thanks very much, Max!

I’ve forwarded this thread to the manager of the cinema and I’ll let you know the outcome.

Tim

[IoannisSyrogiannis]

If the forum had a "like/thumbs up" feature, I would use it on StephW999's post.
It explains the issue and provides the solution without involving third parties.

If a system does not support HFR or 50fps, it won't in the future. It most probably is past its development era. Making a screen server run a 2D DCP in 3D will force the server to duplicate its frames, to play "correctly". In some cases, like Dolby's DSS200, it will also change the color space sent from the media block to the projector, needing another preset.

Not the DCP creator nor the staff at the cinema, much more the audience, will benefit from trying to force the system to do more than what it's capable of. If that could be an option without compromising the content, in other words, if forces of the industry that do have that kind of influence could introduce higher framerates universally, it would have been done years ago and that barrier of 250Mbps for those systems would have been dropped. Create different versions of the DCP and adapt to the systems' specifications. Hacking, won't get you far.

[trwh]

Making a screen server run a 2D DCP in 3D will force the server to duplicate its frames, to play "correctly".

Carsten’s first suggestion is to set the playlist to 2D though, which sounds like a sensible and easy fix to try. I’d be interested to know which of the suggestions upthread risk the projector dropping frames as this is clearly undesirable. My guess is anything involving specifically setting 3D on, but I’m happy to be corrected.

If the media server and projector are capable of displaying the content at 50p it will certainly look smoother, which will benefit this style of content. And I expect you’ll find a range of opinions on what constitutes a simple fix versus a hack!

[Carsten]

Doremis HD-SDI Systems are spec'd up to 60fps/2k. So, no hard technical reason to avoid a 50fps DCP. Besides that, we do not even know wether it's a HD-SDI System, it could also be an IMB system.

Bildschirmfoto 2023-08-16 um 00.31.47.png

But, a 2D HFR channel is not always set up on the projector to support the necessary color model. So, for a wide release, avoid anything above 25fps, but if you want to show a specific HFR feature in a specific cinema, you can always try to get it working. Forcing the SPL to 3D and/or sending a projector macro to enable a 3D channel is necessary.

AVATAR 2 has been delivered in 2D 48fps (among other versions). Some cinemas had configs adjusted in order to play this HFR DCP. But not every cinema did spend the money on a tech visit just to enable HFR playback and so just played the 24fps version. Normal cinema installations during the last 15 years or so typically had only setups that supported 24/25/30 fps 2D/3D. The average 'projectionist' or cinema operator usually does not have the skills or access level to change these configurations.

- Carsten

[trwh]

Following up as promised - the cinema have adjusted their settings to screen my content in 2D on a 3D channel and we’re good to go!

Many thanks to everyone who contributed here,

Tim

PS - the projector is an NEC NC1200C.