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Author Topic: Convolver, JRSS, and channels  (Read 5803 times)

davewantsmoore

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Convolver, JRSS, and channels
« on: January 08, 2017, 12:40:51 am »

Hi.  I'm still on MC20, so I hope this gets noticed by the smart and helpful.

I've read everything I can find, and done a lot of tinkering (got some results) ... but am still slightly unsure about they way I should be approaching my situation for digital XOs (convolver) and surround sound.   Hopefully someone can set me straight.
  • I have 4 speakers (full range, ie. no subwoofers)
  • I want to mix all types of content to 4 speaker surround
  • Each speaker is 3-way active, and I will use the convolver for the digital crossovers (so there will be 12 outputs)
  • I'm using mono wav files for each speaker driver, referenced in a convolver config file

Initially, what I tried was:
  • Setting Output Format / Channels = 4, and turning on JRSS
  • Making a convolver config file with 4 inputs and 12 outputs
  • ... and trying to route each of the 4 inputs, to the channel/output numbers on my interface

This didn't work ... troubleshooting showed that the convolver was not recognising output channels that were numbered higher than 4.

So.... after reading some more.   I have got them impression there is another approach I should be using .... but I just want to check that I'm not heading off in the wrong direction.


If I create a convolver config which as 12 inputs and 12 outputs .... and the set Output Format / Channels = 12 ....  then this works (yay!), and via the convolver config file, I can output to all the outputs on my audio interface.   (I've tested, this is actually sending the convolved output correctly).   Great.

... but my understanding for JRSS with Output Format = 12 channels, is that JRiver is now mixing to a 7.1 target   (but I only have 4 speakers).

Is that right?   If so, am I right to think that now what I need to do, is to use the Parametric Equalizer to fix this issue by mixing channels.   ie.  (for the right half)
  • Make my rear speaker by adding SR and RR together
  • Put the subwoofer back into the main speaker, by adding Sub to R
  • Put the center back into the main speaker, by adding C to R   (or I can tick the convenient box, which says "move C to L/R")

Is this the right approach?    It would be nice if I could just set my output format to 4 channels + JRSS .... but if I really need to setup the output format to 12 channels (and then use a convolver file with 12 inputs and 12 outputs) ... then I will.

Sorry for the lengthy post (didn't want to leave any thing out) .... I hope someone can set me on the right path.   Thanks.


PS - If this IS the right approach.   Then I may ask for some advice for the best way to do these PEQ fixes, like how to add the C and Sub to the L/R, and how to go about properly "creating" my rear channels (by adding side and rear surround channels together?)
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mattkhan

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Re: Convolver, JRSS, and channels
« Reply #1 on: January 08, 2017, 02:28:47 am »

Unfortunately the output format is not decoupled from the mix target so I think your understanding is correct. What is the source content format?
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davewantsmoore

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Re: Convolver, JRSS, and channels
« Reply #2 on: January 08, 2017, 04:12:33 am »

Thanks Matt.   I would like everything (stereo, and 5.1+) to be mixed to 4-channel surround.
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mattkhan

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Re: Convolver, JRSS, and channels
« Reply #3 on: January 08, 2017, 04:50:31 am »

I suspect you'll need 2 zones, one for stereo and at least one for multichannel as the mixing rules will be different in each case.

You can use the "for stereo sources, only mix to 2.1" to maintain a stereo signal for the stereo zone and then it's just a case of getting that signal to the rears in whichever way you choose.

For multichannel I'm not sure whether you'll want to handle 7.1 content differently to 5.1. I suspect you'll be better off without jrss anyway so you just get a 5.1 or a 7.1 signal and then you choose how to fold that down into your available channels. If you do use jrss then you'll get it upmixing 5.1 to 7.1 and then you'll be mixing that back down to 4.0, seems a bit pointless.
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davewantsmoore

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Re: Convolver, JRSS, and channels
« Reply #4 on: January 08, 2017, 08:20:35 pm »

I suspect you'll need 2 zones, one for stereo and at least one for multichannel as the mixing rules will be different in each case.

Thanks again, appreciated.   Yes, probably.

... but before I go any further, I'd like to confirm the approach I should be using.


Output format / channels = 4 (my number of speakers, ie L, R, SL, SR)
OR
Output format / channels = 12 (the number of outputs I need the convolver to work with) ... and then manually (in PEQ) mix the channels from 7.1 down to 4.


I've noticed a few people kicking around on these forums (mojave!?) who seem like they will be able to confirm it for sure.

As mentioned, once I've been told which approach to follow ....  and assuming I need to "fold down" the channels to get the 4 I want ... then I will have some questions about the best way to do that  (eg. use JRSS, or not.... and how to 'blend' 7.1 into 4).

Cheers.
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mattkhan

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Re: Convolver, JRSS, and channels
« Reply #5 on: January 09, 2017, 12:44:20 am »

You will need to use 12
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zydeco

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Re: Convolver, JRSS, and channels
« Reply #6 on: July 28, 2019, 01:26:04 am »

Thanks again, appreciated.   Yes, probably.

... but before I go any further, I'd like to confirm the approach I should be using.


Output format / channels = 4 (my number of speakers, ie L, R, SL, SR)
OR
Output format / channels = 12 (the number of outputs I need the convolver to work with) ... and then manually (in PEQ) mix the channels from 7.1 down to 4.


I've noticed a few people kicking around on these forums (mojave!?) who seem like they will be able to confirm it for sure.

As mentioned, once I've been told which approach to follow ....  and assuming I need to "fold down" the channels to get the 4 I want ... then I will have some questions about the best way to do that  (eg. use JRSS, or not.... and how to 'blend' 7.1 into 4).

Cheers.

I'm attempting the same process but, at this point, just for 2.0 to 5.1. The issue is that I need 8 output channels for to cater for my active speakers so JRSS mixes to 7.1. Any idea as to the correct formula for going from 7.1 to 5.1? Is it just as simple as adding SL = SL + RL or is there more sophistication required to get the fold-down correct?
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mattkhan

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Re: Convolver, JRSS, and channels
« Reply #7 on: July 28, 2019, 02:26:45 am »

I don't know how jrss does it but https://www.gearslutz.com/board/post-production-forum/956530-7-1-5-1-fold-down.html describes a few approaches I have heard of

I don't think there is one true way to do this though, probably the preferred approach will depend on your actual speaker layout (relative to a theoretical 7.1 layout)
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zydeco

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Re: Convolver, JRSS, and channels
« Reply #8 on: July 28, 2019, 03:40:46 am »

I don't know how jrss does it but https://www.gearslutz.com/board/post-production-forum/956530-7-1-5-1-fold-down.html describes a few approaches I have heard of

I don't think there is one true way to do this though, probably the preferred approach will depend on your actual speaker layout (relative to a theoretical 7.1 layout)

Much appreciated. I'll give Ls = Ls + (Lrs-1.2dB) + (Rrs-6.2dB) and Rs = Rs + (Lrs-6.2dB) + (Rrs-1.2dB) a go.

Is there another solution that would allow me to just use JRSS to mix to 5.1 but still support 8 channel output? It doesn't look as if one can upmix to 5.1 whilst having 7.1 output channels. The other option might be to use an external solution for convolution but I'm struggling to find a decent option (and it'll create a few logistical issues as Audiolense provides a config. file that just works with JRiver).
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mattkhan

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Re: Convolver, JRSS, and channels
« Reply #9 on: July 28, 2019, 03:44:28 am »

Is there another solution that would allow me to just use JRSS to mix to 5.1 but still support 8 channel output? It doesn't look as if one can upmix to 5.1 whilst having 7.1 output channels. The other option might be to use an external solution for convolution but I'm struggling to find a decent option (and it'll create a few logistical issues as Audiolense provides a config. file that just works with JRiver).
you can use the 5.1 in a 7.1 container option in output format for this purpose
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zydeco

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Re: Convolver, JRSS, and channels
« Reply #10 on: July 28, 2019, 04:02:37 am »

you can use the 5.1 in a 7.1 container option in output format for this purpose

Thanks - that's the perfect solution for me and will simplify the situation considerably.
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