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Author Topic: DSD to PCM conversation on the fly: MC or MC +DAC  (Read 529 times)

Manfred

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DSD to PCM conversation on the fly: MC or MC +DAC
« on: May 08, 2020, 04:22:48 am »

Do I understand that correctly:

If MC converts DSD to PCM (if sampling rate conversion table in DSP Studio in the DSP Studio is done, bitstreaming off), MC internally converts DSD64 to 352.8K PCM, 128 to twice that, 256 to 4x that.  Then, using SoX, the PCM conversion table downconverts it to the specified sampling rate. Now there are two possibilities:

My Devialet internally converts everything to 192kHz. I have now two possibilities:

1.) Downsample e.g 352.8K PCM to 176,4 kHz (division by factor 2) using MC and then let my Devialet do the Up-sampling. Is SoX used to do the downsampling by a factor 2?
2) Downsample e.g 352.8K PCM to 192 kHz using SoX.

If 1.) is using two algorithm's, MC downsampling by a factor 2 + Devialet up-sampling to 192 kHz; is 2.) then preferred because only one Sampling algorithm (SoX) is applied?


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Hendrik

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Re: DSD to PCM conversation on the fly: MC or MC +DAC
« Reply #1 on: May 08, 2020, 04:51:31 am »

If you know there is a specific rate that your DAC is going to resample to, then doing it in one step in MC is probably better. The "division by 2" is somehow "better" argument doesn't apply to fancy complex algorithms like SoX rexampling all that much.
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dtc

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Re: DSD to PCM conversation on the fly: MC or MC +DAC
« Reply #2 on: May 08, 2020, 07:28:52 am »

I agree with Hendrik that you wold be hard pressed to hear a difference between SoX  converting to 176 or 192.  It is the case,however,  that integer conversions are faster using SoX on MC. So, if there is any issue with CPU performance, converting to 176 and letting the DAC convert to 192 may be preferable. But, if you PC can handle it, just let SoX convert to 192.
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Manfred

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Re: DSD to PCM conversation on the fly: MC or MC +DAC
« Reply #3 on: May 08, 2020, 08:52:34 am »

Thanks for all your replies! Your thinking represents my thoughts :). And MC runs without a glitch on my i3 and I have no performance issues.  Converting DSD 512 (x8) to PCM 24/192 on the fly leads to a CPU utilization of ~23% on my i3-7100 and ~5-6 GB memory utilization. All 4 threats are even used - good multithreading of MC!
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dtc

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Re: DSD to PCM conversation on the fly: MC or MC +DAC
« Reply #4 on: May 08, 2020, 09:12:58 am »

You might also note that as of version .73, Audio Path reports the low pass filter that is being used when doing the DSD to PCM conversion.

Devialet makes nice products :)
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Manfred

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Re: DSD to PCM conversation on the fly: MC or MC +DAC
« Reply #5 on: May 08, 2020, 09:34:41 am »

Quote
You might also note that as of version .73, Audio Path reports the low pass filter that is being used when doing the DSD to PCM conversion.

Yes I noticed it! As always - great work by the MC team!
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