We did some tests with EasyDCP and a 5.1 DCP with HI + VI and a `MainSoundConfiguration of 71/L,R,C,LFE,Lss,Rss,HI,VIN and it passed. Doesn't mean that it's right though!

It does look suspicious though, you're right.

A few random data points... Here are some examples of DCPs we've been sent for festivals which use 51/:

DCP made by Deluxe with Cipher CplGen 1.8.23 (8 channels):
51/L,R,C,LFE,Ls,Rs,HI,VIN

DCP made by Eikon with wl-cpl + Pylua v3.6.6 (8 channels):
51/L,R,C,LFE,Ls,Rs,HI,VIN

DCP made by Motion Picture Solutions with Packman 3.6.3 (6 channels):
51/L,R,C,LFE,Ls,Rs

DCP made with Fraunhofer IIS easyDCP Creator+ 4.1.2 (16 channels):
51/L,R,C,LFE,Ls,Rs,-,VIN,-,-,-,-,-,-,-,-

DCP made with Fraunhofer IIS easyDCP Creator+ 4.1.2 (6 channels):
51/L,R,C,LFE,Ls,Rs

The first 2 are Netflix releases and the 3rd is Universal. That doesn't necessarily mean they're right, but I guess more likely to be.

I've searched our database and we haven't seen any DCPs at all in past year tagged 71/ except for ones made with DCP-o-matic.

Actually, come to mention it, DCP-o-matic DCPs use Lss and Rss whereas all other DCPs from other software use Ls and Rs.

Contrary to what I said in first message in this issue, we've never seen 51/L,R,C,LFE,Lss,Rss, only 51/L,R,C,LFE,Ls,Rs.

We haven't received any 7.1 DCPs with SMPTE metadata so unable to advise what channel naming is used in those.

The Lss/Ls difference should be between 5.1 and 7.1 (5.1 should use Ls, 7.1 Lss). Thanks for the references - they sound convincing!

5e5a45917066e23be7ab8237c8dd63b21a69784e

Thanks Carl.

What will be written if the DCP has a different audio layout e.g.:

• Mono (C channel only)
• Stereo (L+R only)
• 3.1 (L, R, C, LFE only)
• 3.0 (L, R, C only)
• No audio ("MOS")

I guess other layouts are theoretically possible, but the above are all seen "in the wild" fairly regularly.

The 2 really common ones are stereo (very common in shorts), and mono (not unusual in old "archive" films).

From commit 5e5a45917066e23be7ab8237c8dd63b21a69784e, it looks like only 5.1 and 7.1 are options.

One other point (let me know if this should go in a separate issue):

When making a VF DCP to accompany an existing OV DCP, MainSoundConfiguration in the VF can be misleading if the OV doesn't have 16 channels.

e.g.: OV DCP has 6 audio channels only (5.1).
When making a VF, VF has MainSoundConfiguration: 51/L,R,C,LFE,Ls,Rs,-,-,-,-,-,-,-,-,-,-.

I believe this should reflect the number of actual channels in the DCP, so just 51/L,R,C,LFE,Ls,Rs (without the trailing ,-s).

I think the excessive channels in VFs is fixed now. The documentation about this whole thing seems very vague but it seems like only 51/... and 71/... are allowed. Do you have any counterexamples from "reputable" sources?