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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?
Follow Ups:
macs.
:-)
;)
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
Could be.
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.
"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
any DAC built to non-proprietary standards doesn't need a driver.
Nothing wrong with drivers...
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.
What is meant by PCM 48/32? Do you mean 32 bit resolution and 48kHz sampling rate?? I don't think so.
Edits: 07/02/15
"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
Edits: 07/02/15
48000.0 Hz 2 ch 32 bit integer (in english)
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....
Yes, OSX re-samples everything to what is set in the Audio Midi settings.
The Well Tempered Computer
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.
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. :-(
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
Edits: 07/02/15 07/02/15
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.
Good. Glad to hear it! Enjoy.
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.
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