Am 02.08.2014 um 12:33 schrieb Ben Edwards:

I guess my question was is 4444 overkill (have started another thread on this as it is a different question).   'compatibility with a short snippet', is this a Premiere Pro CS6 output option, I have not come across it.  Being sent export via post so need to try to get it right first time.

Your content WILL be converted to 4:4:4/12Bit anyway, as this is the only format supported in a DCP now. The question is, should this happen in Premiere, or in DCP-o-matic/FFMPEG? 
You probably know that the fourth '4' in 4444 effectively is not used here, as alpha channels have little use in final compositions. If you have access to a high quality screening system, it would be interesting to test both variants. 
I won't challenge Carl on this, but I would at least assume that Premiere does a better job directly from the timeline - because the up-conversion/requantisation takes place before the ProRes compression. I would again assume that in DCP-o-matic then, only Prores decode and color conversion takes place prior to J2K compression. There would even be a better workflow in creating the xyz J2K directly from within Premiere, as it leaves out the intermediate Prores compression. 
That said - there can be differences between theory and practice when converting between different codecs, because some of their internal dealing with scaling, subsampling, gamma handling, colour conversion etc. is obscure. Then finally, even things done technically wrong or less optimal can still look better on screen ;-) So, nothing goes over visual testing.


Thanks. I seem to remember it is possible to convert un-encrypted DCP to other formats playable on computers.  so its either full encryption/KDM or totally open and piratable?

That's right, however, currently it is quite complicated to pirate an unencrypted DCP. At least it goes beyond the knowledge of most projectionists. There are no simple tools available to do that. If you don't put your DCP on the internet, the risk is fairly low. Some cinemas just keep unencryped content on site in order to play it occasinally for internal use, but they usually won't make business with it.

The important thing to notice with encrypted DCPs and KDMs is that there is no universal key that works for all cinemas. A KDM is only valid for a single specific machine. KDM service companies/distributors maintain huge databases of cinema locations with all their certificates in order to be able to issue KDMs reliably in daily operations. This database is the core of their operations. So you need to reason if you want to take up that part yourself. Usually no problem for a specific screening, but in the long run it could become an issue to generate and maintain your own database.

OK, where do I add certificate, cant see it in 'Make KDM'? 

Yes, the Make KDM Dialog will allow you to setup a database of cinemas and screens, attach their certificates, and then select one of them for KDM creation.


Interesting point, I actually project at a cinema and the commercial DCPs we get have sound levels all over the place.  The logo audio are sometimes very loud, and this may be for the reason you say, but that makers the film too quiet.  We tend to put an audio queue at the beginning that raises the volume after logo. Basically we have to play bits of the film to set the levels.  There is also the issue that a full auditorium sucks up a lot of audio so the level needs to be higher but lets not get into this.

Actually the cinema environment is the only one with an internationally agreed perceptive loudness standard. There is still some variance in it, and I guess this will never be solved completely (one major issue is different expectations for entertaining loudness between 'typical' younger and older audience), but in general it works well. The formal reference setting at all cinemas is 'Fader level 7'. Actually most cinemas I know play preshow at 4.5-5.5 and main features at 5-6, though. If you do a screening at a cinema, check the processor setting yourself in the booth or on the wall control (if there is one). In my opinion, you should aim for your preferred loudness being reached at 5.5 to 6. 

This could become a long discussion, but in general, the reference level in nearly all digital cinemas should be the same, but the way projectionists, ushers, equipment, control, etc. are able to do adjustments on content with non-standard levels is different. In some locations, staff just dials in something on the wall control, then forget it for the next week. In other cinemas, levels are set automatically from the server per feature. There is one automation system I know of that actually takes the number of sold tickets for a specific auditorium and adjusts volume +/- to compensate for more or less crowded auditoriums.

Commercial DCPs sometimes come with notes suggesting preferred fader settings to make sure the content is played back at the directors preferred level. E.g. 'Gravity' came with suggestions to play at level 7.2 (! the .2 is hilarious). And I just have an accompanying letter for a DCP between my fingers which says: 'Do not play this movie louder than 5.5' ;-) And that is NOT an action movie, but an arthouse flic. Looking forward to check it.

These numbers may not tell you much, but the difference between 5.5 and 7.2 on the same feature is typically between 'just right' and 'deafening'.

I notice that 'highend' productions typically can be played more towards the 7 - e.g. we played 'Gravity' and 'Lincoln' at 6.5 without any complaints, and I guess 7 would have been still ok, at least in a full auditorium.


- Carsten