[Help] Theatrical 4.1 → 5.1: duplicate mono surround at full level or attenuate by 3 dB?

[ash_82]

So theatrical 4.1 mixes are effectively L, C, R, LFE and a single mono surround channel (Cb).

If I want to sync and preserve one of these mixes, I'll eventually need to export it as a standard 5.1/6-channel file.

My current approach is to duplicate the mono surround channel and route the copies to channels 5 and 6, so that the exact same signal is sent to both SL and SR.

My question is: should each surround channel be attenuated by 3 dB in that case?

I can't remember whether the original mono surround channel in a 4.1 theatrical mix was already compensated for this, or whether modern AVRs apply their own level compensation when they distribute a single surround channel across left and right surrounds.

How do you usually handle this when converting a theatrical 4.1 mix to standard 5.1?

[stwd4nder2]

tbh I would just encode it as 4.1 DTS and let the user's audio processor deal with it

[ash_82]

Unfortunately I’m not set up for DTS encoding

[stwd4nder2]

There's a cracked copy of the encoder suite out there. I'd recommend just grabbing that, it's useful to have.

[ash_82]

Thanks for the info I’m going to look into it

[ash_82]

After further research, I have confirmation that each surround channel needs to be attenuated by 3db in this scenario (AVRs do compensate when they have to spread Cb to SR and SL)