Stereo loudness in a 5.1 package

[flores.33]

Hi Everyone,

I'm looking for some feedback on audio levels on a film we're submitting for a festival. We only have a stereo mix of the film, so we're exporting it as a 5.1 file with audio only routed to the left and right channels. I'm trying to make sure the loudness is correct for a theater screening. This might be more of a post audio question, but thought I might try here since we're using dcp-o-matic.

When I mixed the film, I was aiming for an integrated loudness at -27 lufs with no peaks. When DCP-o-matic analyzed the audio levels, it came back with an integrated loudness level of -29. I'm only assuming that it was a different level because it was measuring the audio as if it was a 5.1 mix and not a stereo mix.

If that is the case, would it be better to adjust the gain to -27 lufs or keep it at -29 lufs? For what it's worth, the film has played in other theaters and festivals with no feedback about the levels being off, but I'm not sure if the audio was adjusted for those screenings. This is the first time we're doing the DCP ourselves.

Any help is appreciated. Thanks!

[Carsten]

-27 LUFS is a bit too soft for typical cinema screening. I see, however, that your peaks already are close to 0dB, so, there is not much you can do, at least not within DCP-o-matic. You could increase loudness a little bit by using the Mid/Side decoder/upmixer.
Essentially, it adds another (center) speaker, so this will make up for the soft volume to a certain extent.