issue with Atmos re-render downmix controls
 

Hi,

I am monitoring in 7.1.4, mixing mostly drama for streaming, and I've recently moved from 5.1 to Atmos mixing.

I noticed that surround channels in total sound noticeably weaker/quieter when listening 5.1 re-render compared to full 7.1.4. By default, side- and back channels seem to be lowered 3db when combined to 5.1 rear, and I feel it's too much.

I could adjust the downmix controls in the Dolby renderer, but the issue is 5.1 and 2.0 don't have separate controls, and I want to keep surrounds at -3db in stereo re-render!

How do you deal with this? Or are you happy with the balance in all re-renders as they are?

I worry about re-renders, because the main delivery format for most of my stuff is still 5.1 or even stereo in some cases.

Re: issue with Atmos re-render downmix controls
 

In Atmos all speakers are to be calibrated equally loud. The renderer compensates for that on the 7.1, 5.1 re-renders.
Do you have your surround speakers maybe calibrated wrong in Atmos? They should all be equal level as the front. In 5.1 they should be -3 per channel compared to the front. Just a thought to rule out the b-chain.

Re: issue with Atmos re-render downmix controls
 

Yes, my room is correctly calibrated.

I might have been a bit unclear describing the issue. If I have a signal (object or bed) panned directly to, for example left rear speaker, it will be played back 3db lower in 5.1 re-render compared to full atmos mix. In both cases the signal comes out from the same speaker in my room, so only thing that changes when moving from listening atmos mix to 5.1 re-render is 3db drop in volume.

Re: issue with Atmos re-render downmix controls
 

You can't separate trim controls in 5.1 and 2.0 for the moment in the Dolby Atmos Renderer, you could ask Dolby on their forum about this.
You could record your re-renders live in Pro Tools using a spanner for your 5.1 on an aux before the recording audio channel, but for offline rendering (which I do in PT) there is no alternative way.

Re: issue with Atmos re-render downmix controls
 

Remember ... Theatrical 5.1 the surrounds are lowered -3. In Home theater
all speakers are the same level( such as 82 spl each speaker) .

Re: issue with Atmos re-render downmix controls
 

I think I know what you’re hearing. It’s to do with the pan law.
ProTools as you know uses constant power panning and so when you down-mix the 7.1.4 to 5.1 it sums the 4 surrounds (and heights) to the 2 surrounds it now has by -3db , to give you a constant powered pan through the back of the room. I’m guessing what you’re hearing is that a single static source that’s panned directly to the rears or sides appears lower in level when you switch to 5.1 downmix. Panned to the middle of the two surrounds in 7.1 it will sound a bit louder. But over all this gives you a balanced image.
Saying that I don’t think my mixes in 5.1 sound weaker in the surrounds as a whole. In fact the opposite. I think there can be a lot of build up.

In the Theatrical version of the renderer they give you options to change this relationship.


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Re: issue with Atmos re-render downmix controls
 

Thanks for the replies. Yes, this seems to be the case. I am basically mixing and delivering 5.1 mixes at the moment, just mixing them in Atmos enviroment. So basically all my surround stuff is in sides, and therefore all of it will be -3db in re-renders.

I'll just monitor 5.1 re-render from now on when mixing 5.1 content, to hear the correct balance.