Near-field mix in wide-field environment

[flmmkr]

At a screening recently we found that our surround channels were not very loud. We were told this was likely due to the 5.1 audio being mixed for near-field instead of wide-field. Instead of paying for an expensive re-mixing for wide-field, is there a way to compensate for this in DCP-o-matic? The mix sounds great on home theater systems, so we don't want to change that. But it's a movie getting into festivals, and we'd like those screenings to have better surround sound. Could we raise the audio levels of the surround channels in DCP-o-matic and have that work well? If so, how many db would be ideal? Is there any other way to compensate for playing a near-field mix in a large theater?

[Carsten]

Hmm. I understand that, as you took the effort for a surround mix, you want to actually hear the surrounds in the cinema. However, in this situation, 'people like you' tend to exaggerate a bit. Surrounds being too loud can be very confusing. When you listen to professional surrounds mixes, you will notice that the best mixers use surrounds in a very reserved way. In my personal opinion, the best use for surrounds is for atmospheric or spatial effects, not directional effects. Also keep in mind that, unlike in most home theaters, cinema surrounds are usually set up 'around' the audience, not just in the back of the auditorium. That's the reason why they are called 'surrounds' - they surround the audience. As such, directional effects will only work for some very special locations, or on a side-to-side basis.

Anyway - if you think the surround is too low in your DCP, you can easily raise the level of the surrounds only in DCP-o-matic. I suggest you try two or three different versions and test them out in a KNOWN good cinema (not the one you mention in your 5.1/7.1 thread ).

Best is probably to check in at least two different cinemas.

You can adjust per channel gain in the audio matrix - right click on the green connecting point between content and DCP channel, each for left and right surround. I'd suggest you try +3dB, +5dB, +7 dB. Creating VFs for these versions is very easy and fast, as DCP-o-matic will only recompute the audio, but reuse the unchanged video.

Name your files accordingly, so when you play them, you know which is which.

- Carsten

Bildschirmfoto 2017-06-18 um 23.25.29.jpg

[flmmkr]

Thanks again, Carsten. I'll try the VF mix in the DCP. I have another movie I'm more involved playing at another theater in a couple weeks, so I wanted to make sure I get it right.

They talked to the theater owner for this upcoming screening and were told that they would allow the producers to check the movie before the screening and that they could increase the surround level for them to their liking. I know that doesn't fix anything for future screenings without that kind of control, but for this one screening does it sound like that would work okay?

And still is there anyway to automatically compensate for a near-field mix when making a DCP? Or is that strictly something that can only be done at the actual mixing stage, which would require a theater size mixing space?

[Carsten]

They talked to the theater owner for this upcoming screening and were told that they would allow the producers to check the movie before the screening and that they could increase the surround level for them to their liking.

Actually, I don't think that will happen. Changing the channel balance on a cinema system is not something local staff is usually able to do. Changing sound balance is usually hidden deep in the processor config software, that is nothing the operators have access to. In theory, they could just turn the pots on the amps up - but in an ATMOS auditorium, there are many amps going to many individual speakers, and it is not easy to get a decent overview about that. This setup is delicate and expensive - Honestly, if I'd find my staff playing with amp volume controls in order to get a festival or test screening right, I'd immediately fire them

No, sound systems for cinema are calibrated, and need to stay calibrated. They are calibrated individually for all modes of operation, 5.1, 7.1, and ATMOS. That said, I have seen and heard weird things happening even on very expensive installations. But as ATMOS installations are extremely expensive and only carried out by reputable installers, I can hardly imagine this specific system is setup in the wrong way.

As I said, get the 'official' Dolby 5.1 and 7.1 test DCPs. You can also load them into DCP-o-matic and see how they do the routing, so you can compare it with your own DCP. The CP850 has a couple of front buttons to choose from different presets - one should be 5.1, another 7.1, you don't need to care about ATMOS. Play the 5.1 test DCP while sitting in the middle of the auditorium, or L/R centered slightly towards the back. Make sure no one is playing with the cinema processor while you are listening. Make sure daily staff or tech advisors from that cinema power up the booth.

The only thing a standard cinema should be able and willing to do is to adjust their channel configuration between 5.1 and 7.1, and adjust the overall playback level. Everything else should not be fiddled around with for any dedicated screening. The usual cinema processor will not allow more than that.

I don't think what you experienced there is the difference between nearfield and theatrical mixes.

- Carsten

[scozz76]

In cinemas there's a 3dB difference between stage and surround when performing the output level calibration.

85dB Left / Centre / Right
82dB Ls / Rs

You may want to keep this in mind when mixing. My editing setup has the output channels setup as per the dolby level calibration.

[crokante]

So, in an already finished 5.1 mix for streaming (in near field), it will be enough to raise the rear channels by 3db? o still a good idea to test different values, like suggested before as +3, +5 +6 dB?

Thanks!

[Carsten]

I would at least try +3 and +6 dB for surrounds.