MPD, JRiver and DSD

[vmartell22]

Hello

 

Have a question regarding playback of DSD files on non-DSD DACs thru conversion with MPD and/or JRiver. 

 

I actually found by accident that MPD did the conversion. Once in a while, I use JRiver - reading on JRiver's support for the same conversion,  JRiver indicates that it applies a filter to DSD to PCM conversion on non-DSD equipment to eliminate low frequency content that could be harmful. Started looking for indication that the same was true of MPD's conversion; however, have not been able to find any indication that MPD applies a filter of that kind - anybody knows if that is the case? if it is true that DSD conversion can produce frequency content that may damage equipment (as per JRiver) guessing is would be irresponsible for MPD not to do so.  I might be stoopid, because my searches did not turn up the info so I ma daring to ask. 

 

I assume, the damage might occur at high volume, but wanted to double check just in case.

 

Thnx!

 

v

[rayooo]

Are you sure as you mention it's:  "low frequency content"?

 

I was aware of this from the JRiver wiki:

"The default low-pass filter is at 24kHz using a 48dB/octave slope. The low-pass filter can be selected via Tools > Options > Audio > Advanced > Configure input plug-in > JRiver DSD Plugin."

 

I was not aware they were doing any filtering of low frequency content. ??

[vmartell22]

23 minutes ago, rayooo said:

Are you sure as you mention it's:  "low frequency content"?

 

I was aware of this from the JRiver wiki:

"The default low-pass filter is at 24kHz using a 48dB/octave slope. The low-pass filter can be selected via Tools > Options > Audio > Advanced > Configure input plug-in > JRiver DSD Plugin."

 

I was not aware they were doing any filtering of low frequency content. ??

 

No - you are correct - I was writing from memory and was incorrect  - had it backwards - gist of the question remains - I remember reading in JRiver's doc (or somewhere else, maybe this forum) that it was done because it might be harmful - and since I had it backwards, no wonder I could not find it.

 

Did another search at mpd, now with the right terms, mpd dsd lowpass filter.  

 

https://github.com/MusicPlayerDaemon/MPD/blob/220d9528a3251aaeb789e75d4f649ac04b9a9001/src/pcm/dsd2pcm/dsd2pcm.c

 

I think they do - would you agree?

 

v

 

 

[rayooo]

 looks like with standard rate DSD... the filter is flat to 48khz.

 

..at least according to the program notes. 

 

 

 

 

 

[Ron Scubadiver]

foobar2000 can convert DSD to PCM if foo_sacd_input is installed.  Some of the options have ultrasonic filters built in.  

[mansr]

3 hours ago, rayooo said:

 looks like with standard rate DSD... the filter is flat to 48khz.

 

..at least according to the program notes.

Here's the frequency response of the filter:

As the code comments say, it is pretty flat up to 48 kHz. With an output rate of 352.8 kHz, the right half of this spectrum gets folded back, the start of the stop band landing in the vicinity of 70 kHz, again in agreement with the comments. From 70 kHz to limit of 176.4 kHz there will be aliasing to varying degrees. With a typical DSD noise distribution, quite a bit of it will remain in this range. A bit too much, if you ask me.

[vmartell22]

21 hours ago, mansr said:

Here's the frequency response of the filter:

As the code comments say, it is pretty flat up to 48 kHz. With an output rate of 352.8 kHz, the right half of this spectrum gets folded back, the start of the stop band landing in the vicinity of 70 kHz, again in agreement with the comments. From 70 kHz to limit of 176.4 kHz there will be aliasing to varying degrees. With a typical DSD noise distribution, quite a bit of it will remain in this range. A bit too much, if you ask me.

 

Mansr - thanks so much for the education -  really appreciated

 

While I am happy that mpd deals with it - definitely JRiver's filter seems like a better approach. 

 

Thnx!

 

v