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Author Topic: DSD DSP/output assistance with Channel mapping and Room correction  (Read 3079 times)

scottm_dj

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All the parametric/tools and filters apparently do not work in bitstreaming mode--which is the only way i can find to send true DSD to my exasound DAC :(   Does anyone know a J River 20 setting to allow this?  This is my request and the follow up from the DAC vendor regarding J River settings.  But none of this works in bitstream mode...can anyone help?  I have version 20...if something is available in 21 i'll upgrade in a heartbeat.

Q:  In the mch mode is there any way to differentiate small vs large surround speakers, or set a subwoofer crossover level?   I fear blowing out my rear speakers esp with intro to 'Welcome to the Machine' as I'm sending full-range signal to all my speakers!
A:  This type of processing can be done by J River.  Under the Audio Settings tab check DSP and Audio format (Room Correction)

Q:  Is there any way to software assign the unused (7.1) DAC 7 and 8 jacks to "repeat" the Front L/R outputs so I can send 2ch material to preamp 2ch expansion circuit?  I cant use that with the MCH input.
A:  In J RIver, go to Tools->Options->Audio->DSP and Audio format->Parametric Equalizer->Add->Mix Channels>Mode->Copy Channel
 
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scottm_dj

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #1 on: January 22, 2016, 10:55:58 am »

I see this is partially addressed below with the "speaker distance" post (which makes sense)...but I really am hoping to do the channel mapping copy (I have 8 analog outs and want to copy the signals from 1 and 2 over to 7 and 8.  This should be independent of the bitstreaming format i would think?
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blgentry

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #2 on: January 22, 2016, 11:20:57 am »

You are correct:  DSP will not be applied to any sources that you set up for Bitstreaming.  Why?  Because bitstreaming doesn't touch or alter the bits.  It just sends them.  To use the DSP, it would have to convert DSD to PCM, then apply PCM and (optionally) convert back to DSD.

All of the things you ask for are possible without bitstreaming.  But impossible with bitstreaming.  Many surround sound preamp/processors can do crossover, time alignment, etc.  Many of them process in the PCM domain though, so it would likely involve the same conversions; they would just be hidden inside of the pre/pro .

Maybe you should try using MC without bitstreaming and see how you like the sound.  Then you can use the DSP to do everything you want.  Or not.  Just a suggestion.

Brian.
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mattkhan

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #3 on: January 22, 2016, 11:49:01 am »

I think the request is just breaking it down so that bits are streamed on a per channel basis instead of as a whole. This could allow certain functions, that aren't really dsp as such, to be applied to those channel streams (like delay and move/copy). Whether the jriver audio engine is amenable to that is another question entirely (easy to imagine a major change would be required to support such functionality).
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blgentry

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #4 on: January 22, 2016, 03:26:07 pm »

Matt:  He's asking for crossover as his first request.  Then time delay as his second. 

I agree with you that even time delay seems like it would require a lot of engineering effort because to do precise timing implies a sonic library that can introduce these delays into the bit stream.  How are multichannel DSD streams laid out?  They must be muxed in some way.  Adding delay would seem to require unmuxing, processing the channels for delay and then remuxing.  This seems like potentially a big can of worms to open.  So I agree that this probably won't happen.  But who knows, neither of us work for JRiver.  :) 

Crossover is entirely out of the question without converting to PCM or writing an entirely new DSD processing subsystem that is able to natively manipulate DSP on DSD streams.

Brian.
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mattkhan

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #5 on: January 22, 2016, 04:08:09 pm »

ah fair point, I thought he was just asking for the ability to copy channels rather than do any meaningful signal processing on them. My guess is that takes the probability of it being implemented from extremely tiny to zero :)
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scottm_dj

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #6 on: January 22, 2016, 06:55:45 pm »

Thx all for input.  Yes...I kinda figured out that the timing/crossover (software) adjustments were not going to be available.  I'd really like to get the "copy channel" working though so I can use by 2ch expansion circuit.  Here is what my DAC can process via USB:

USB - This is the recommended and most capable input. It supports 2 to 8 channels PCM and
DSD. PCM is supported with 32 bit resolution at standard sampling frequencies from 44.1 kHz to
384 kHz. DSD sampling rates range from 2.8224 MHz to 12.288 MHz


If I didn't do the bitstream route, what would be the next best way to get the cleanest signal...and hopefully allow for my requests?   If I had two unused rca outs (Back surround) how would I duplicate the signal going to FL and FR?  Would that be "copy" or "add" channel mix?

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blgentry

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Re: DSD DSP/output assistance with Channel mapping and Room correction
« Reply #7 on: January 22, 2016, 07:18:42 pm »

If I didn't do the bitstream route, what would be the next best way to get the cleanest signal...and hopefully allow for my requests?

It's just a guess, but 352.8 kHz would probably work well.  By default, MC will decode 1xDSD to 352.8kHz.  2xDSD will go to double that.  If you want to play 2xDSD, you should probably set 705.6kHz to down sample to 352.8kHz in DSP Studio > Output format > Sample rate .

Quote
If I had two unused rca outs (Back surround) how would I duplicate the signal going to FL and FR?  Would that be "copy" or "add" channel mix?

I would say Copy is the way to go.

Brian.
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