Using a beamer as second screen for public presentation

[farbenblind]

there are two problems: first there is screen tearing that can be fixed with vsync, and then there is skipping of frames as the frames per seconds of the source material do not match the frames per second of the projector/monitor.

the second one is visible quite obviously with slow camera pans or with scrolling credits. if you playback a 24fps video on a 25fps playback system, then you can detect short shutters each second, same with 30 and 60fps playback system.

the fix is to use your operating system to set the correct fps of your external monitor/projector. some media player do that for you, but at least with the projector i use the projector needs some time to adjust to the new framerate (single chip dlp) so i set the frame rate some seconds before i start the film.

is it really that professional playback systems use a fixed playback frame rate of 60fps? you will definitely see some stutter with that setup, there is no way around?!

[IoannisSyrogiannis]

I understand that my input does not answer the original question, but since streamfuchs mentions that they are not very familiar with DCPs, I will write this, so it's here.

If one deals with DCPs that are either unencrypted or that can have KDMs issued for a specific installation of DCP-o-matic, it doesn't make sense to play out of DCP-o-matic Player. No automation, high demand on CPU power and fast storage, etc. etc. to only result in a precarious (in terms of reproduction) set-up for video and audio.

Feedback from experimenting is great to have here. So, please, whoever knows more, share. But when systems that encode well faster than 24 or 25 fps don't work well enough with reproduction, things are bound to be less than ideal during paid-for screenings.
If you have the means and don't risk your relation with distribution, it's more sensible to go for exporting to ProRes and playing that with a Media Player that would allow you to at least have some basic automation and an audio processor that would carry the weight. (Audio glitches are way more „obvious“ and annoying than video ones).

[streamfuchs]

the fix is to use your operating system to set the correct fps of your external monitor/projector. some media player do that for you, but at least with the projector i use the projector needs some time to adjust to the new framerate (single chip dlp) so i set the frame rate some seconds before i start the film.

Just to make it clear:
When testing I connected the second screen output via HDMI with the projector.
I made shure that the graphic card output which feeds the projector is running with the same framerate as my content is. Doing so I forced the projector to operate in this very framerate.
As far as I know there is no way beside this, to adjust the projector to a specific framerate.

[streamfuchs]

If one deals with DCPs that are either unencrypted or that can have KDMs issued for a specific installation of DCP-o-matic, it doesn't make sense to play out of DCP-o-matic Player. No automation, high demand on CPU power and fast storage, etc. etc. to only result in a precarious (in terms of reproduction) set-up for video and audio.

Feedback from experimenting is great to have here. So, please, whoever knows more, share. But when systems that encode well faster than 24 or 25 fps don't work well enough with reproduction, things are bound to be less than ideal during paid-for screenings.
If you have the means and don't risk your relation with distribution, it's more sensible to go for exporting to ProRes and playing that with a Media Player that would allow you to at least have some basic automation and an audio processor that would carry the weight. (Audio glitches are way more „obvious“ and annoying than video ones).

When there is an unencrypted DCP it would be in deed no problem to take the MXF - file and to recode it to whatever.
We made very good experiences with digital media players by brightsign playing back MP4-Material.
This operation is completely without any problems or any stutter. It works just as it should.
So this could be a workaround for unencrypted DCP

But with enctypted DCP packages I of course can not recode the MXF-file what leads us back to problem.

[farbenblind]

I made shure that the graphic card output which feeds the projector is running with the same framerate as my content is. Doing so I forced the projector to operate in this very framerate.

this sounds good to me. then its still possible that your computer is too slow to play back the dcp.

as IoannisSyrogiannis already mentioned, it's also an idea to convert the DCP to a different format. i'm using ffmpeg to convert DCPs to PorRes for years now and never had problems with dropped frames.

[IoannisSyrogiannis]

[...]
But with enctypted DCP packages I of course can not recode the MXF-file what leads us back to problem.

Indeed it does.

Yet, what Carl wanted to relay from the beginning is the following:
When a distribution company sends you a KDM for the installation of DCP-o-matic Player for a specific DCP and for a specific period of time, they also allow your DCP-o-matic authoring/main application to decrypt it (with the same KDM). Thus, also allowing you to export it as a video file (ProRes or mp4).

That is the reason that distribution companies are reluctant to issue KDMs for DCP-o-matic Player (or have a policy against it). Because if they do, they can not control what you will do with that DCP, which you will be able to decrypt and re-author or export with DCP-o-matic.

To conclude, using DCP-o-matic to export to ProRes or MP4 is possible whether the DCP is not encrypted or if it is encrypted, but you have been issued a KDM for DCP-o-matic (Player).

P.S./Edit: The KDMs that are issued for any other system are not fit to work with DCP-o-matic.

[cvila]

Hi just a question... I've never used the kdm system in DCP-O-Matic.

Is the server certificate the same for the main DCP-O-Matic app and the Player app? That seems odd to me.

I'm used to EasyDCP where the Player and Creator have separate server cerfificates. Oddly enough it's the Player application that has the ability to export an unencryped DCP (or transcode) from an encrypted DCP.
Thanks

[carl]

Is the server certificate the same for the main DCP-O-Matic app and the Player app? That seems odd to me.

Yes, they are the same. Do you see an advantage in making them different?

[cvila]

Well, I don't know really but maybe it would help to make distributors less restrictive when issuing kdms for just the DOM Player which has no export functions.

The 2 or 3 times I tried using the DOM certificate to receive a DKDM from a distribution company it got rejected, stating the software is not DCI compliant. I don't know what beaurocracy and fees you would need to go through for DCI Membership but I can imagine it.. But that's another story...

[StephW999]

The 2 or 3 times I tried using the DOM certificate to receive a DKDM from a distribution company it got rejected, stating the software is not DCI compliant. I don't know what beaurocracy and fees you would need to go through for DCI Membership but I can imagine it.. But that's another story...

Hello,
Dom Player can't be DCI, since the private key is available and can easily be used to decrypt a KDM sent by a distributor (key Id, key data contained in the "cipher value").