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Author Topic: JRSS for 5.1 with 24 Channel Output Possible?  (Read 2413 times)

dwalme

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JRSS for 5.1 with 24 Channel Output Possible?
« on: March 21, 2015, 01:10:28 pm »

Hi,

I am using 24 channels of output via ASIO using a Motu 24Ao.   I have a 5.1 speaker setup which many of them are configured for 3 & 4 way active crossovers using convolution.

What is the correct way to configure the output format in order to use JRSS upmixing/downmixing?   

I select 24 channel output in order to use convolution and active crossovers, but then I notice JRiver is trying to upmix to 7.1 which I do not have.

I'm also want JRSS to downmix 7.1 to 5.1.

What's the best way to configure JRiver for this?

Thank you,
Dan
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davewantsmoore

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Re: JRSS for 5.1 with 24 Channel Output Possible?
« Reply #1 on: May 29, 2015, 03:14:25 am »

I am using 24 channels of output via ASIO using a Motu 24Ao.   I have a 5.1 speaker setup which many of them are configured for 3 & 4 way active crossovers using convolution.

What is the correct way to configure the output format in order to use JRSS upmixing/downmixing?   

I select 24 channel output in order to use convolution and active crossovers, but then I notice JRiver is trying to upmix to 7.1 which I do not have.
I'm also want JRSS to downmix 7.1 to 5.1.
What's the best way to configure JRiver for this?


I have a similar setup requirement   (I have a stereo setup, which are 5 way active speakers, and I would like to use convolution for the crossovers) .... so I would like jriver to downmix everything to stereo, and then convolve this with 5 channels output per side.    What is the way to achieve this?
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mwillems

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Re: JRSS for 5.1 with 24 Channel Output Possible?
« Reply #2 on: May 29, 2015, 07:08:47 am »

There isn't currently a good "default" way to do what you all are describing.  All channel counts above 7.1 have a hard coded mixing target of 7.1.  There have been feature requests in the past (which I've signed onto) to be able to specify the channel output and mixing targets separately, but that hasn't gotten a lot of traction.

But both of you can do what you want, just not solely with JRSS.  OP, you just need to manually downmix from 7.1 to 5.1 using parametric EQ.  Davewantsmoore, you'll need to manually downmix to stereo, unfortunately.  If you had four-ways instead of five-ways you could use the "2-channel inside a 7.1 channel container" option, but there is no equivalent option for five ways at the moment.  The JRiver team is generally responsive to user needs, but they've also got a lot going on development wise, and this is, unfortunately, kind of a niche area.

I run bi and triamped speakers in various applications myself, so I feel your pain, and being able to specify the mixing target more granularly would be handy for me too, but in the meanwhile we can accomplish what we want manually using PEQ.
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mojave

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Re: JRSS for 5.1 with 24 Channel Output Possible?
« Reply #3 on: May 29, 2015, 12:26:48 pm »

I would set my channels to 24 and use JRSS. This will upmix to 7.1 as you already know. I would then use the following channels for my 5.1 input:
1 - Left
2 - Right
3 - Center
4 - LFE
5 - not used
6 - not used
7 - left surround
8 - right surround

For 5.1, you will have the exact content as the original. JRSS doesn't do anything to existing channels.
For 7.1, I recommend not down mixing and just over writing channels 5 & 6 for the active crossovers.
Here is why I'm not a fan of down mixing:
  • There is a lot of 5.1 content that was matrixed to 7.1 to create "discreet channels". The info is actually already in the side surrounds. By the way, some of the new Dolby Atmos mixes are also just matrixed from 5.1 or 7.1.
  • Sounds that are originally designed to be discreet don't sound right when down mixed. For example, bullet shots, airplanes, and other panning sounds may have a delay and or reverb in the rear surround to give the impression of travel past you. When you down mix, the original signal is stretched or changed due to the delayed signal being added. The sound is no longer as crisp, clear or dynamic.
  • You can't remain energy neutral when down mixing since you don't want the surrounds to be too loud compared to the rest of the content. This means you will have to lower the level of the existing side surround content to allow for the added channels. Sounds that were only mixed in the side surrounds will now be much quieter than they should.
  • If you convert video to audio in JRiver and open the multi-channel wav file in Audacity, one finds that the rear surrounds typically have less content than the side surrounds.

You might be concerned about the bass that is in encoded in the rear channels of 7.1 content. When you think about the subwoofer level being 10 dB higher than the other channels, and then adding 5 other channels of bass already, the last two channels will really add only about .5 dB of output if the bass is coherent with the other channels. If it is incoherent bass, it will be even less. Either way it is not really noticeable.
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