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WTF?

76.220.25.80
Posted on July 2, 2015 at 13:44:27
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 Just go a 'new' DAC that purports to display input sample rate, hooked it up the the USB port of the MacBook Air with the worlds cheapest 2 meter USB cable and it sounds GREAT driving my DH600 cans but...

Display on the DAC seems to think that the audio format it's seeing is PCM 48/32. Without playing music the display reads PCM 48/16 but the second I hit play it's reading 48/32.

Even an album that I think I downloaded from the net at 24/96 or even higher rez plays on VLC at what ppurports to be PCM 48/32.

OK. sounds great but I'm a bit puzzled.

Does OS-X up-sample the output of even Spotify?




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

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RE: WTF? , posted on July 2, 2015 at 13:47:38
Roseval
Audiophile

Posts: 1846
Joined: March 31, 2008
 Yes, OSX re-samples everything to what is set in the Audio Midi settings.


The Well Tempered Computer

 

RE: Ah yes..., posted on July 2, 2015 at 13:58:26
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 Foolish me thinking it's in the 'sound' settings.

That said, 24/192 re-sampled to 32/48 sure sounds GOOD!

Too bad Apple Midi can't auto select.

That said, it sounds great either way.




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: WTF? , posted on July 2, 2015 at 14:01:37
AbeCollins
Audiophile

Posts: 46302
Location: USA
Joined: June 22, 2001
Contributor
  Since: February 2, 2002
This is true but players like Pure Music and Audirvana Plus (and others) can bypass Core Audio and automatically match and switch the sampling rate for you. However, I'm not sure if these players will work with Spotify and streaming services via web interface or an App. They work nicely for playing music files.


 

Well, I can certainly hear the difference between streaming 16/44.1 Lossless FLAC..., posted on July 2, 2015 at 14:11:13
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 and files stored on my computer at Hi Rez (don't know exactly).

It would not surprise be if I can bypass Apple Core Audio with VLC and just don't know how. :-(




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

bit confused here......., posted on July 2, 2015 at 17:59:51
Tom Schuman
Audiophile

Posts: 2632
Location: Bremen
Joined: October 22, 2003
What is meant by PCM 48/32? Do you mean 32 bit resolution and 48kHz sampling rate?? I don't think so.

 

Yep..., posted on July 2, 2015 at 18:32:06
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001



48000.0 Hz 2 ch 32 bit integer (in english)


First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: bit confused here......., posted on July 2, 2015 at 18:41:15
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 "What is meant by PCM 48/32? Do you mean 32 bit resolution and 48kHz sampling rate?? I don't think so."

Yes, the common interface formatinside computer systems today for PCM data is typically 32 bit (IEEE) floating point as it enables digital signal processing without overload and/or loss of resolution. The extra bits aren't doing much for you unless the computer is doing DSP, but then they aren't costing anything either because the computer data is processed more efficiently on word boundaries. Normally this is not stored in computer files to save space on disk, but it is common to store intermediate files created by audio editors and other post processing software in 32 bit floating point since this avoids the slight degradation from each conversion from 32 bit floating point back to 24 bit fixed point.

It is possible to hear changes to 24 bit audio files where only the low order 24th bits change. How signals at such a low level are perceived defeats my understanding, but they can be perceived, at least by some people.

Another format used by some software and some DACs is 32 bit integer. This is what I send from HQPlayer to my Mytek DAC when sending PCM. This is even higher resolution than 32 bit floating point if the signal levels are properly scaled, but this is less practical for software that does complex DSP. Also, most processors have been optimized for floating point arithmetic.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

macs, posted on July 2, 2015 at 18:49:47
bullethead
 macs.

 

RE: Yep..., posted on July 2, 2015 at 18:51:06
Tom Schuman
Audiophile

Posts: 2632
Location: Bremen
Joined: October 22, 2003
 There's an app which identifies the actual software settings of any USB device, look up TDD v. 1.83.0 descriptor dump it will tell you what the input sampling capacity of the DAC is, but it presumably only tells you what the DAC designer wants you to know......
I did find out from this program (and from reviews) that my (built in 2010) DAC from Musical Fidelity is limited to 48kHz native on the USB input, the slightly later version was updated to 192kHz, but whether anyone in their right mind could identify these differences from a blind test remains to be determined....

 

At least I don't need to install a 'driver'..., posted on July 2, 2015 at 19:21:15
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 :-)





First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: Well, I can certainly hear the difference between streaming 16/44.1 Lossless FLAC..., posted on July 2, 2015 at 20:52:36
AbeCollins
Audiophile

Posts: 46302
Location: USA
Joined: June 22, 2001
Contributor
  Since: February 2, 2002
 You cannot bypass Core Audio with VLC alone. Bypassing Core Audio is just one of the claims to fame with those other players like Pure Music, Audirvana Plus, Amarra, etc., along with other features like disabling services, setting OS priority for music playback, memory play, etc.

Through the use of software like Audirvana Plus, you bypass Core Audio so it's out of the picture and does no sample rate conversion at all. AV+ can be setup to pass the file at it's native resolution from the Mac to DAC without altering it.... Or you can choose to alter some files.

For example, in Audirvana Plus I normally have it set for direct mode, exclusive access (hog) mode, integer mode and to not alter sampling rate at all, EXCEPT for my 16/44.1 files which get sampled 2x using the iZotope SRC via the Custom Settings.

The end result is also displayed correctly on the Ayre and the Oppo screens. On the Ayre my CD rips show up as 88KHz (2x 44.1) and my other files display natively as 88, 96, 192.

Audirvana Plus Preferences. Selet modes and memory

Select Sample Rate Converter and when and how it's used

Custom sample rate settings. Only my 44.1 files are converted 2x

Disable unneeded services and set OS priority for music. Other services and
processes can be disabled manually or through scripts



 

Got it hooked up to the SONOS Connect now..., posted on July 2, 2015 at 21:08:27
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 via optical. Using the USB input only for YouTube, etc.

Very little difference when changing sample rate, at least for streaming internet Lossless FLAC.

Only have one or two Hi Rez files on my MacBook Air and they sound great.




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: At least I don't need to install a 'driver'..., posted on July 2, 2015 at 22:18:22
Bob_C
Audiophile

Posts: 2667
Location: NY
Joined: July 31, 2000
 Nothing wrong with drivers...

 

RE: Got it hooked up to the SONOS Connect now..., posted on July 3, 2015 at 00:19:57
AbeCollins
Audiophile

Posts: 46302
Location: USA
Joined: June 22, 2001
Contributor
  Since: February 2, 2002
 Good. Glad to hear it! Enjoy.

 

your talking to a Linux guy, posted on July 3, 2015 at 05:00:47
bullethead
 ;)

 

Does Linux use 'drivers'?, posted on July 3, 2015 at 08:12:09
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001


Could be.





First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: Does Linux use 'drivers'?, posted on July 3, 2015 at 08:56:55
bullethead
 I don't use third party drivers except for my Nvidia video card, I need that to work with Display port and my 4K resolution monitor.

audio in MAC and Linux if the hardware is working properly it doesn't need a 3rd party driver.

 

RE: Does Linux use 'drivers'?, posted on July 3, 2015 at 10:20:26
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 "audio in MAC and Linux if the hardware is working properly it doesn't need a 3rd party driver."

This is not true for DACs that require special drivers, such as the Mytek.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: Does Linux use 'drivers'?, posted on July 3, 2015 at 15:46:29
bullethead
 any DAC built to non-proprietary standards doesn't need a driver.

 

I don't need to install a 'driver'..., posted on July 5, 2015 at 22:10:20
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 This seems to be a fundamental thing with MAC users. How anyone can determine whether a driver is better or worse is beyond reason.

At least with some windows drivers on XMOS and other systems, one can set buffer sizes with a Control Panel. This is good customisation.

 

But the problem with Linux is that ALSA is not optimized for playback, posted on July 7, 2015 at 06:47:48
Gordon Rankin
Manufacturer

Posts: 2928
Joined: June 9, 2000
 BH,

If you have looked at the code they are really stingy about the resources the ALSA stack uses. Actually much less than even Windows does.

As a UNIX programmer from day 1, I can tell you my other beef is that people who write really good code for Linux, are just not getting paid. Then there are these other programmers that develop code that is just so so and the whole damn audio section is based on that.

Nothing's perfect!
Gordon
J. Gordon Rankin

 

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