Mono sound on a DCP?

Hi everybody -
I’m brand new to DCPs and it’s turning out to be a lot more complicated than I expected.

My project deliberately has a retro feel. The entire thing, except for the music, is in mono. So far I’ve edited the entire thing in the center channel, and for the theatre release I was hoping to add a touch of stereo width to the music when there’s dialogue.

Everything I’ve read about DCPs says the audio should be in 5.1 and I have to buy software for the audio. Is this true? Some mono sound effects would only play out of one speaker when in a stereo track, although I’m sure I could convert them to stereo and the mono track would play in L and R…so should I convert all of my audio clips to stereo, and then change the tracks to 5.1?

Also, is the only option to purchase software such as Penteo or DTS?

Again, very new to this and it’s probably simpler than I realize, but it feels overwhelming at the moment.

Thank you

Hello there! DI, DCP author and college educator who's taught a lot of folks how to make DCPs here.

First and foremost, let's get something technical out of the way that'll be relevant down the line. Delivery-format audio channel assignment for theatrical 5.1 is *always* the following:

1. Left
2. Right
3. Center
4. LFE
5. Left Surround
6. Right Surround

(Post-Audio Pros will affirm that they often don't mix (as a verb) in this channel assignment, but the Mix (as a noun) will most certainly always be this when it hits both the theater and the home viewer.)

I would *strongly* encourage you to always mix your theatrically-aimed films in a 5.1 environment, either done by yourself or a professional mixer. Notice I say "in a 5.1 environment" and not "make a 5.1 mix." You can totally make a mono mix if you like and have it play in a theater via DCP! You can even add in some stereo elements, effectively making a "3.0" mix, where most of your audio comes out of the Center speaker, with some elements (maybe music, maybe some "choice" panning sound effects like passing cars and planes and the like) come out of Left and Right speakers.

The salient point to always bear in mind when mixing for modern theaters is this: While not all movies are mixed in 5.1, (damn near to) all theaters are *equipped* for (minimally) 5.1 mixes. More to the point, (damn near to) all cinema servers *expect* for your audio to be mixed in 5.1, and for your DCP to be flagged as having a 5.1 mix, as that has been Academy reference standard for many years.

Given this, the safest bet in making sure that your DCP encounters no issues interfacing with either the cinema server or the speakers in the theater is to always deliver your audio in a 5.1 container, whether your audio is 5.1 or not.

Here's the big, not-exactly-secret trick we DCP authors use: You just render out the unused channels as silence!

In the case of a purely Mono mix wrapped in a 5.1 container, this would mean that your audio channel assignment would be:

1. Left (Silence)
2. Right (Silence)
3. Center (Mono Mix)
4. LFE (Silence)
5. Left Surround (Silence)
6. Right Surround (Silence)

For a 3.0 mix:

1. Left (3.0 Mix Left)
2. Right (3.0 Mix Right)
3. Center (3.0 Mix Center)
4. LFE (Silence)
5. Left Surround (Silence)
6. Right Surround (Silence)

Now, another thing you could do (which I want to emphasize, I do not expressly recommend) if you don't have access to a 5.1 mixing environment is to mix the film in Stereo, panning what you want to eventually hit the Center channel to the middle, and then use a mid-side decoder to split apart your Stereo mix into 3 channels, with your center-panned audio being your newly-made Center channel track (you can find mid-side decoders in a number of DCP authoring softwares, as strictly Stereo mixes can cause a problem in theaters where dialogue "bounces" around the space and phases in unintended ways). Again, it is far better to mix your film as it will nominally appear.

As for special audio software - it's generally recommended that you mix your film in some sort of DAW (Digital Audio Workstation) such as Pro Tools, Neundo, or the Fairlight page in Resolve. Any other software would simply do the job of "up-mixing" your film automatically.

Hope this is helpful!! DCPs are pretty complex and daunting, and this is just the audio mix side of things. I know many people in this forum might tell you, "it's best to pay a professional to make your DCP for you." And they'd be right - but it's definitely a thing you can learn to do. There are a lot of good resources out there these days for learning the intricate ins and outs of authoring, starting with the ISDCF naming convention page.

https://registry-page.isdcf.com/

Best of luck to you!!

This is very helpful, thank you!

Here's a couple questions I have:

At the moment, I have 24 tracks total (3 2.0 Music tracks and 21 1.0 tracks - 13 individual tracks for character dialogue, 5 SFX tracks, 1 Room tone, 2 footsteps)

The recommendation I've seen for Fairlight is to create those 6 tracks you mention (all of them mono, would that be correct?), and then link them as a 5.1 unit or individually assign the corresponding pan.

In my situation, where I'm already this far along, I'm assuming I don't have to make 5 additional tracks for every single one of my 24 tracks (I hope not). Can I simply create 5 additional tracks for L, R, LFE, LS, and RS, assign them accordingly, and leave them empty?

A question linked to my question above - currently I have a number of audio clips, typically dialogue or footstep but a couple SFX too, that are panned or have a keyframed panning effect to imply movement. How does that best function in this 5.1 set up?

Additionally, I'm curious about the music tracks. If I'm correct about the mono assignment of tracks, does this mean I'm supposed to make the music mono as well? I mentioned earlier that I was hoping to use the "stereo width" effect on certain pieces of music (not all, only the ones that overlap with dialogue, in order for the dialogue to "cut through the middle"). How does this best function in a 5.1 set up?

OR am I overthinking this entirely, and could I get away with leaving my 1.0 and 2.0 tracks as is and routing them to a 5.1 Bus?

Again, thank you for that comprehensive response. Incredibly helpful.

Sam

1. Left (Silence)
2. Right (Silence)
3. Center (Mono Mix)
4. LFE (Silence)
5. Left Surround (Silence)
6. Right Surround (Silence)

The LFE channel has no impact on the spatial feel, does it? Wouldn't we treat this in a mono mix just like in a stereo or surround mix?

I always wondered about the center speaker. Are these speakers in a theater optimized for certain frequencies, for speech clarity for example? Or are they equal to the left/right speakers and what we assign to each of those speakers is really just a matter of spatial placing?