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Author Topic: trying to get just 2.1  (Read 811 times)

Aceman

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trying to get just 2.1
« on: March 02, 2021, 03:57:19 pm »

when i go into the dsp setting i have just 2.1 selected with no upmixing. but when i play a file it says it upmoxing to 5.1 why is it doing this ?
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wer

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Re: trying to get just 2.1
« Reply #1 on: March 02, 2021, 04:06:18 pm »

Welcome to the forums.

Please post screenshots of the entire DSP Studio window when Output Format is displayed, and also of the Audio Path display when something is playing and you're getting that message.

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Aceman

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Re: trying to get just 2.1
« Reply #2 on: March 02, 2021, 04:17:36 pm »

here you go
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wer

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Re: trying to get just 2.1
« Reply #3 on: March 02, 2021, 04:45:48 pm »

MC is doing this for compatibility.  The ".1" in your "2.1" is the LFE or subwoofer channel.  When consumer audio devices transmit/receive multichannel audio, the subwoofer channel is always on channel 4.  There is no channel 4 in a 3-channel format, like 2.1.  So in order to make the LFE signal come out of the subwoofer instead of the center channel (which is the 3rd channel in a multichannel format) MC transmits as 5.1, so that the subwoofer can be on channel 4 as required.

If you look at the analyzer in DSP studio, you will see that the other additional channels are silent.

It's important for you to understand that since you have selected "no upmixing or downmixing" you will not actually get any output on the subwoofer channel, unless your source track is 2.1 channels.  And it is not.  Audio path indicates you are playing a 2-channel track.  So your configuration accomplishes nothing, compared to outputting as 2 channels or source number of channels. In your example, MC is transmitting a silent subwoofer channel.

If you want subwoofer output, you would need to enable "JRSS Mixing" instead of "No upmixing or downmixing" and then use the Subwoofer setting down below to route low frequencies to the subwoofer channel.  In the example you showed, if you're hearing anything come out of your subwoofer, it is your receiver or preamp that is doing that, not MC.   

I hope this helps.
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Aceman

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Re: trying to get just 2.1
« Reply #4 on: March 02, 2021, 04:53:51 pm »

thank you for you response. So is this correct now ? so even though it says 5.1 im only outputting 2.1 
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wer

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Re: trying to get just 2.1
« Reply #5 on: March 02, 2021, 06:02:37 pm »

It's more correct than it was.

Technically you are outputting 5.1, but only 2.1 channels will have any sound in them. That's what's necessary. C, SL, SR will be silent.  So practically you're outputting 2.1.  Whether you want to think of that as 2.1 or 5.1 is up to you. :)

But as far as correctness, I would question the subwoofer crossover point you have selected.  You will have to decide that based on what your main Left and Right speakers can do.  Personally and in my experience, 250Hz is an extremely high frequency to be sending to a dedicated subwoofer. That's almost middle-C.  Only if your main speakers are extremely small and bass-deficient would that be remotely correct, like for a sound bar or micro-satellites.  A more common crossover point would be between 100 and 150Hz if your main speakers are small.  For medium to large speakers, crossover points of 50-80Hz are normal.  Crossing over at 250Hz will affect your stereo imaging, because you can definitely localize sounds at that frequency.

But that's between you and your speakers. You should check your main speakers' frequency response and set the crossover point appropriately.

I'll also mention it's not desirable to resample everything to 192 unless you have to.  It is better to use integer multiples.  So for example, it is better to resample 44.1kHz to 176.4kHz instead of 192kHz, since 176.4 is an integer multiple of 44.1. There will be a small quality difference, although whether you will be able to hear it or not, I don't know.  If your output device support 176.4kHz, use it.

Good luck...

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40th.com

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Re: trying to get just 2.1
« Reply #6 on: March 03, 2021, 03:05:03 pm »

When consumer audio devices transmit/receive multichannel audio, the subwoofer channel is always on channel 4.

Not quite right.

https://docs.microsoft.com/en-us/windows/win32/api/mmreg/ns-mmreg-waveformatextensible

specifically this:

The dwChannelMask member specifies which channels are present in the multichannel stream

The low-down on that is the channels in the stream as sent to the system can be specified, and should be specified.  Yes, if you have your sound device set to 7.1 in the Sound control panel, that stays 7.1 even if you send 2.1 data to Windows.

Use SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_LOW_FREQUENCY and the PCM stream as sent to Windows (shared) may be L,R,LFE,L,R,LFE,... no need to put an empty center channel in there.

What JR actually does when set to 2.1 (shared mode) I don't know, but this is about "the subwoofer channel is always on channel 4" which is not true.

To shorten, I edited this to remove references to Exclusive mode.
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