Sound between mid-side decoder and handmade 3 channels

[stifler8]

Hi guys
I have an urgent question about the sound in the dcp-format. There should be a screening of my film in the cinema soon, so I made a dcp-file for the cinema theatre. This is a documentary in stereo (speech predominates).
By dcp-o-matic, I’ve made two files with two different sound options: 1 - mid-side decoder, 2-I’ve duplicated the stereo channels in the center-channel and I’ve turned down - 6 db on each channel and then I’ve turned -6 db for all three channels.I've reduced the sound peaks to the -21-20 LUFS.
I don't have the ability to listen this recording except in stereo and so I can't decide which track will sound better (1 or 2), since on stereo on my mac they are very similar. Here are the graphics from dcp-o-matic and I’m asking you to help me to understand which of these tracks will be better for the cinema.


Appreciate for you recommendations!
Andrei

[Carsten]

Hmm, from the pictures I assume this is a 'dialog-only' part? Because I don't recognise much stereo content in L/R in either of them.

Both will probably sound okay, I would still opt for the mid-side decoder, simply because it will actually try to put dialog only into the center, and doesn't sacrifice the stereo as much. You can see in your handmade 3channel version that essentially all three channels carry exactly the same signal.
From a standard center listening position in the cinema, they would probably sound pretty similar, depending on how you balance the center channel in.



You could try to listen to the created audio MXF in audacity, or load the DCP into DCP-o-matic again and disable either L/R or C in the audio matrix while playing - that way you can check what is actually contained in these channels, even if you only have a stereo listening environment.

[stifler8]

Carsten, thank you very much for the detailed answer!
I also thought in the direction of this option. And I'll try to listen to the channels separately in audacity.

[Carsten]

You need to install the FFMPEG plugin for audacity in order to open the audio MXF files from DCPs. From what I see in your audio plots, your overall levels look alright for the cinema as well.