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Author Topic: DSD over DoP implementation  (Read 6457 times)

hlesser

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DSD over DoP implementation
« on: January 22, 2014, 01:11:45 pm »

I'm using the Chord QuteHD running MC 19 (latest version 19.0.108) on a Win 7 64 bit machine.  The Chord handles PCM up to 24/192 as well as DSD64 using DoP protocol.

I'd like to be able to play all files in their native format WITHOUT losing access to JRemote volume control -- i.e., bit perfect won't work since the DSP is bypassed.

My current options (both of which work) are:
(1) Converting all PCM files to DSD, or
(2) Playing all PCM files natively and converting DSD to 24/176

Isn't there a way to implement native playback of all formats? The Chord, and presumably other DSD-capable DACs, are able to detect and switch to DSD flawlessly. 

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6233638

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Re: DSD over DoP implementation
« Reply #1 on: January 22, 2014, 01:54:34 pm »

As I understand it, the only way you would be able to adjust the volume of DSD is to either convert it to PCM, or use an analog volume control.
If your DAC allows you to adjust the volume of DSD and uses a digital volume control, then it's converting to PCM internally.
 
If you use DSD Encoding, Media Center is converting DSD to PCM and then encoding that back to DSD. Volume control would be applied in the PCM stage.
Personally, I prefer to convert DSD to 24/176 and output that, as there's one less conversion stage. (and I believe my DAC works in PCM internally anyway)
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Hendrik

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Re: DSD over DoP implementation
« Reply #2 on: January 22, 2014, 02:23:01 pm »

Do i understand correctly that its not possible right now to output native DSD files as DoP, while still producing PCM for native PCM files? There is a bitstream option for DSD, but I assume it doesn't do DoP?
Without actually having a DSD DAC, its all a bit complicated to follow.

Of course bitstreaming DSD via DoP would mean you don't get volume control.
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~ nevcairiel
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6233638

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Re: DSD over DoP implementation
« Reply #3 on: January 22, 2014, 03:24:00 pm »

You can bitstream in a DoP format without any problems - you just lose the volume control when doing this.
Hlesser wants to bitstream DSD (in a DoP format) and be able to adjust the volume.
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Hendrik

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Re: DSD over DoP implementation
« Reply #4 on: January 22, 2014, 03:28:11 pm »

All I see is options to bitstream native DSD files (similar to bitstreaming compressed audio over HDMI, without an option to trigger between DoP and non-DoP), and real-time encoding everything to DSD/DoP.
I must be missing the option in question. :)
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~ nevcairiel
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6233638

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Re: DSD over DoP implementation
« Reply #5 on: January 22, 2014, 03:34:41 pm »

All I see is options to bitstream native DSD files (similar to bitstreaming compressed audio over HDMI, without an option to trigger between DoP and non-DoP), and realt-ime encoding everything to DSD/DoP.
I must be missing the option in question. :)
It was moved into the ASIO output options fairly recently - presumably to simplify the bitstreaming options, though it has caused some confusion.
 
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6233638

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Re: DSD over DoP implementation
« Reply #6 on: January 23, 2014, 04:20:14 am »

I just wanted to add that I see why this change was made now - I was concerned that it might mean that bitstreaming may no longer work via WASAPI, but it seems that WASAPI will automatically detect whether native DSD or DoP is required by your hardware now, and only ASIO needs this option.
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Earwaxxer

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Re: DSD over DoP implementation
« Reply #7 on: February 10, 2014, 08:15:58 am »

Ok I'm a bit confused with the volume control and DSD over DoP option. I am using the iFi iDSD and output on the MC 19 is x2 DSD over DoP, using WASAPI driver on a Windows 7 computer. If I turn on internal volume control it does in fact work. Now these are redbook files being converted to DSD my MC. Does than mean MC converts the redbook to DSD then to PCM adjusts volume, then back to DSD again for output?
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Hendrik

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Re: DSD over DoP implementation
« Reply #8 on: February 10, 2014, 08:49:11 am »

Red book as in normal Audio CD? Those start out as PCM.
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~ nevcairiel
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6233638

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Re: DSD over DoP implementation
« Reply #9 on: February 10, 2014, 08:50:17 am »

Ok I'm a bit confused with the volume control and DSD over DoP option. I am using the iFi iDSD and output on the MC 19 is x2 DSD over DoP, using WASAPI driver on a Windows 7 computer. If I turn on internal volume control it does in fact work. Now these are redbook files being converted to DSD my MC. Does than mean MC converts the redbook to DSD then to PCM adjusts volume, then back to DSD again for output?
Volume can only be adjusted in PCM. If you are playing a CD rip, it is natively 16/44 PCM audio.
 
So you adjust the volume in PCM, and then encode to DSD.
 
For DSD native tracks, they have to be converted from DSD to PCM to adjust the volume, and then get encoded back to DSD.
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LenWhite

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Re: DSD over DoP implementation
« Reply #10 on: March 23, 2014, 02:16:42 pm »

I'm using a Windows 7 Intel/I5 laptop as a music server after implementing the changes recommended at http://wiki.benchmarkmedia.com/wiki/index.php/Windows_7_Audio_Playback_-_Setup_Guide. I've also disabled the McAfee anti-virus.

The music server is connected to an EMM Labs XDS1 v2 via a Kimber Kable AG USB B-Bus directly into the XDS1 USB digital input. The XDS1 v2 USB digital input is functionally equivalent to the EMM Labs DAC2X.

I installed the supplied EMM Labs audio driver and selected the XMOS XS1-L1 driver on the music server which is now the active sound driver. I've confirmed this via the Windows audio settings.

In the JRiver MC19 Tools/Options/Audio audio settings I selected the TUSBASIO audio driver option because from reading the HELP system it sounds like ASIO is the preferred option. But now I realize there are three other options I should consider labeled Meitner Audio 2.0 Output (Kernel Streaming), XMOS XS1-L1 Audio (WASAPI), and XMOS XS1-L1 Audio (Direct Sound). I've been playing FLAC and DSD files using the ASIO setup and they sound very good, but now I'm not sure this is the optimal setting.

I had also been experiencing a few dropouts occasionally when listening to computer music files. So last week I disabled the McAfee anti-virus and for the past couple of days haven't experienced dropouts. But just after disabling the anti-virus I felt I was hearing a slight "hardness" in the reproduced sound, and it sounded louder at the same album sound settings I had recorded in my music spreadsheet. I have no idea why this would be unless it has something to do with the laptop responding to the lessening of cpu demand as a result of limiting the McAfee real time scans.

Anyway I then took another look at the laptop sound card settings and ended up lowering the volume, ultimately deciding on a setting of 65. I also checked the box disabling any sound card enhancements such as bass boost. IMO this significantly improved the mid-range clarity, overall transparency, and tightened the bass. A friend told me this is counter to what he has read on forums like Computer Audiophile.

Now I'm beginning to question all the settings! When playing pure DSD or DSF files I'm confused whether I should check mark the MC19 Audio Device/Device Settings DSD bitstream in DoP format. From reading it appears DoP is used to play DSD via PCM!

Can anyone comment on the settings I've made and whether I should change any of them? Are any of you using EMM Labs XDS1 v2 or DAC2X with JRiver?
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Len

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Re: DSD over DoP implementation
« Reply #11 on: March 23, 2014, 03:23:07 pm »

In the JRiver MC19 Tools/Options/Audio audio settings I selected the TUSBASIO audio driver option because from reading the HELP system it sounds like ASIO is the preferred option. But now I realize there are three other options I should consider labeled Meitner Audio 2.0 Output (Kernel Streaming), XMOS XS1-L1 Audio (WASAPI), and XMOS XS1-L1 Audio (Direct Sound). I've been playing FLAC and DSD files using the ASIO setup and they sound very good, but now I'm not sure this is the optimal setting.
ASIO is generally the preferred option. If you are experiencing drop-outs during playback, try increasing the size of the ASIO buffer, both in Media Center and in the device's settings.
 
Tools → Options → Audio → Audio Device → Device Settings… will let you set the Media Center buffer size, and the Open Driver Control Panel… button will take you to the device's settings. (which may or may not have buffer options)

Anyway I then took another look at the laptop sound card settings and ended up lowering the volume
It would be better to use the Media Center Internal Volume control than Windows' settings. (though they may not have any effect if you are using ASIO anyway, depending on the driver)

Now I'm beginning to question all the settings! When playing pure DSD or DSF files I'm confused whether I should check mark the MC19 Audio Device/Device Settings DSD bitstream in DoP format. From reading it appears DoP is used to play DSD via PCM!
Native DSD or DoP contain exactly the same audio data - it's only the method of transmission which differs.
 
Native DSD outputs a 1-bit 2.8MHz signal.
DoP outputs a 16-bit 176.4kHz signal.

The data contained in the DoP signal is identical to the DSD one - it's simply transferred as sixteen 1-bit chunks combined together in a 16-bit data stream, rather than a 1-bit data stream. (2.8MHz ÷ 16 = 176.4kHz)

If your DAC supports both formats, it should not make a difference which you use.
It's common for many DACs to only support DoP though, which is why the option exists.
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