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Synthesize Additional Channels in a Home Theater (like StormXT) with a BSS Audio DSP

mv038856

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Jun 18, 2020
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Hi,

I don't know if I am in the correct forum area for my question, as it is quite basic in parts and very specific in others but here it comes...

I would like to fill channels in my home theater that are not present in the original mix.

Why?
Many Atmos soundtracks might not actually be object based, but are mixed for a certain number of channels.
Some speaker positions like Center Front Height, Front Wide or Top speaker(s) are not supported by some codecs or decoding capabilities of processors/receivers.

Storm Audio has added a feature called StormXT that can supply a signal to speakers that otherwise would stay silent.
I have a number of BSS Audio BLU-xxx devices at hand that I would like to use to do something similar.

Now, my question is, how to do this with the tools that are available in Harman's Audio Architect software on a BSS BLU-806 oder BLU-160 or if this is even possible.

Here is my thinking:
If I want to fill the Center Front Height for an Atmos track, e.g., I would probably use the signals from the Left and Right Front Height Speakers.
But I am at a loss on how to best combine them.

What would a Mixer do if I mix the two channels with no (positive/negative) individual gain? Would it be a mix of the two channels but with the same loudness as in the original channels? If yes, wouldn't that mean that it would create two phantom speakers between the Height Center and the left and right height speakers respectively? Would the overall loudness of the Height left channel signal e.g. be 6dB higher than without the mixing?

Another idea I got was using a Summer to add the signals of the two source channels "on top of each other" and reduce the summed signal by 50% (6 dB again?) so that only signals that really are present in both channels get audible in the center. Would that work? I even considered using a Gate to eliminate signals below a certain level as I would assume that those are not present in both source channels. But would that again bring some loudness balance issues beween the summed center and the original left and right height speakers? Would I have to "subtract" the center signal from the source channels? Can one of the signal processing objects available for the BSS platform do something like "subtracting"? Could I do a 180° phase shift (which signal processing object could do this?) and mix it with the source channel to cancel out the (summed) center signal from the source channel?

Any ideas how to best do it?

Thanks!

Markus
 
I think you will be out of luck for Atmos mixes that are not object based ie. locked to a specific channel output. You could theoretically change the output option and down mix these locked Atmos soundtracks to DD 5.1 in which case normal up mixers in AVRs would expand to your channel count. Dolby up mixer will not support center front height, Auro 3D up mixer would, not sure about DTX pro. Things to consider might be loss of bit rate etc.

People do Scatmos for expanding beyond 15 ch capability of most processors/AVRs by extracting signal and using older up mixers from additional older AVRs to create additional channels. There are lots of threads off AVS Forum on this topic. Never tried so can't say how well it works.

Unfortunately can't help you with Harman's Audio Architect as not familiar with it.

Good luck with your project.
 
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