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Author Topic: Bitperfect Indication  (Read 2543 times)

kgs51

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Bitperfect Indication
« on: March 08, 2022, 11:48:43 am »

I have my system(Win 11)set up with a usb dac of SMSL u9. I am trying to get the latest edition of JRiver Media Center to play bit perfect sound. I followed all of the steps on the Wiki for setting up bit perfect sound but I can't get it to work.
I would appreciate someone be able to help me with this. Please see attachment for basic setup that I did.
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AGAWA

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Re: Having trouble getting Bitperfect playback
« Reply #1 on: March 08, 2022, 12:52:24 pm »

interesting, how one can know when it is bit perfect. How do you find out.
Please enlighten me.
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kgs51

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Re: Having trouble getting Bitperfect playback
« Reply #2 on: March 08, 2022, 01:20:48 pm »

When you are playing a song, in the upper right corner is a cog which must turn blue for it to be bit perfect. Also, if you hover your mouse over the cog, it will say if it is using direct sound etc.
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markf2748

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Re: Having trouble getting Bitperfect playback
« Reply #3 on: March 08, 2022, 09:55:26 pm »

When you are playing a song, in the upper right corner is a cog which must turn blue for it to be bit perfect. Also, if you hover your mouse over the cog, it will say if it is using direct sound etc.
The blue cog sounds like an MQA indicator.  MQA decoding is not supported within MC, but you may be able to bit stream to your DAC for MQA decoding (https://yabb.jriver.com/interact/index.php/topic,125454.msg868904.html#msg868904), if that is what you are trying to do.  If you are sending something other than a valid MQA file, then I expect the blue cog will not light up, even for bit-perfect.

I've tested for bit-perfect transmission from source file through a DAC input with the RME ADI-2 DAC FS.  RME includes a set of audio test files with different bit depths and bit rates.  The DAC firmware continuously monitors incoming bit patterns. If at any time a perfect match is found to one of the test files, then a corresponding notification message appears on its screen.  Using this method I have found MC 26, 27, & 28 are indeed bit-perfect over Windows USB (and over Chromecast Audio Wi-Fi) when (1) MC plays at full volume, (2) no MC DSP applied, and (3) Options> Audio> Advanced> Dither Mode (not zone specific)> No Dithering or JRiver Bit Exact Dithering.
Some discussion here:
https://forum.rme-audio.de/viewtopic.php?pid=158824#p158824
https://forum.rme-audio.de/viewtopic.php?pid=158886#p158886

I'd be curious to learn of other tests for real bit-perfect transmission.  Perhaps a digital loopback of MC's output through an audio interface (or Windows itself?), capture/save it, then compare to input file bit-by-bit.  Maybe Audacity can do it, or a file compare utility.
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Awesome Donkey

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Re: Having trouble getting Bitperfect playback
« Reply #4 on: March 09, 2022, 03:31:44 am »

No, the cog isn't at all related to MQA, it's the button for Audio Path. It may look different depending on skin used.

Nonetheless the easiest way to get bit-perfect audio output is; use WASAPI (or ASIO if your DAC has a driver available) in exclusive mode and don't use any DSP in DSP Studio at all. Exclusive mode is required (as exclusive mode bypasses the system mixer) otherwise you're going through the system mixer, which means it's not bit-perfect. In addition adding any DSP whatsoever makes the output no longer bit-perfect because of the changes it makes.
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I don't work for JRiver... I help keep the forums safe from Viagra and other sources of sketchy pharmaceuticals.

Windows 11 2023 Update (23H2) 64-bit + Ubuntu 24.04 LTS Noble Numbat 64-bit | Windows 11 2023 Update (23H2) 64-bit (Intel N305 Fanless NUC 16GB RAM/256GB NVMe SSD)
JRiver Media Center 32 (Windows + Linux) | Topping D50s DAC | Edifier R2000DB Bookshelf Speakers

kgs51

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Re: Having trouble getting Bitperfect playback
« Reply #5 on: March 09, 2022, 04:01:41 am »

I have gotten bit perfect on my song files.  I believe when I reinstalled my dac driver, that did the trick.             
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markf2748

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Re: Having trouble getting Bitperfect playback
« Reply #6 on: March 09, 2022, 11:46:32 am »

No, the cog isn't at all related to MQA, it's the button for Audio Path. It may look different depending on skin used.
Thanks for the clarification.  Sorry for the confusion; I never meant to imply that MC's very useful DSP button (Audio Path popup) was an MQA indicator!  Apparently there is an LED on the SMSL U9 display which turns blue or green for MQA decoding.

What I described above is an independent way to confirm that in fact MC can operate bit-perfect.  The tests revealed there is some danger in depending solely on the DSP button (Audio Path popup), at least for the Thunderstorm skin I use, since it does not show the Dither Mode setting, which can destroy bit-perfect if set to TPDF Dithering.

Proposal:  Include Dither Mode in the Audio Path whenever it affects the output.
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Awesome Donkey

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Re: Having trouble getting Bitperfect playback
« Reply #7 on: March 09, 2022, 01:40:36 pm »

What I described above is an independent way to confirm that in fact MC can operate bit-perfect.  The tests revealed there is some danger in depending solely on the Audio Path button (at least for the skin I use), since it does not show the Dither Mode setting, which can destroy bit-perfect if set to TPDF Dithering.

To be fair, any sort of dithering or resampling would 'destroy' bit-perfect output in this context.
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I don't work for JRiver... I help keep the forums safe from Viagra and other sources of sketchy pharmaceuticals.

Windows 11 2023 Update (23H2) 64-bit + Ubuntu 24.04 LTS Noble Numbat 64-bit | Windows 11 2023 Update (23H2) 64-bit (Intel N305 Fanless NUC 16GB RAM/256GB NVMe SSD)
JRiver Media Center 32 (Windows + Linux) | Topping D50s DAC | Edifier R2000DB Bookshelf Speakers

markf2748

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Re: Bitperfect Indication
« Reply #8 on: March 09, 2022, 02:22:58 pm »

To be fair, any sort of dithering or resampling would 'destroy' bit-perfect output in this context.
Yes in principle, but ....
With my RME DAC testing, I was surprised to find that under some conditions, the setting
Dither Mode (not zone specific)> JRiver Bit Exact Dithering
still resulted in bit-perfect detection of the test pattern.
It has been a while since I looked into that, and I don't claim to understand what "Bit Exact Dithering" actually is, hence my caveat "whenever it affects the output".

I was also thinking that if something has no affect on the output (like "No Dithering"), then don't clutter the Audio Path window with it.  But maybe it's better to always display the Dither Mode setting (?).

The bottom line is always to compare what comes out with what went in, bit-for-bit.  It would be nice if there was a relatively simple, general procedure to check this, though I imagine it is beyond the scope of MC itself.
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