Decible forcing 16 bit depth on Nuforce HDP DAC

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jgarshon
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Joined: Sun Jun 12, 2011 8:52 pm

Decible forcing 16 bit depth on Nuforce HDP DAC

Post by jgarshon » Sun Jun 12, 2011 9:02 pm

Hi there,

just downloaded this promising app after a great review in Stereophile magazine. I already have the Pure Music app but was looking for an easier way to play the FLAC format without importing the files into iTunes.

The issue I am experiencing now is that, when I try to play any 24/96 flac files through my Nuforce 24/96 capable DAC, the Audio MIDI set up on my macbook pro is resetting to 96K at 16 bit depth only. I have tried switching it to 24 bit manually in the Audio MIDI window but it resets when I try to play any file in Decibel?

The only solution I have found is to disable the "Obtain exclusive access" feature in Decibel's preferences... Doing so however seems to degrade the sound quality severely. The sound becomes "bright and edgy".

Any suggestions here are much appreciated.

JG

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sbooth
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Re: Decible forcing 16 bit depth on Nuforce HDP DAC

Post by sbooth » Mon Jun 13, 2011 12:20 am

When exclusive access is turned on Audio MIDI Setup isn't necessarily a reliable source of information. There is a way to display the audio format that Decibel is actually sending to the DAC, but it requires a small amount of work because it isn't integrated into Decibel's display (yet). If you would like to do this, the first step is to enable logging as outlined in http://forums.sbooth.org/viewtopic.php?f=22&t=3756. The log file will contain a lot of entries- the ones of interest will say something about virtual format. For example, here is an example log entry for my Wavelength Proton when it is not operating in exclusive access mode:

Code: Select all

Virtual format: 2 ch, 44100 Hz, 'lpcm' (0x00000009) 32-bit little-endian float
This means that Decibel is sending 32-bit floating point samples to the OS. Here is an example with exclusive access:

Code: Select all

Virtual format: 2 ch, 44100 Hz, 'lpcm' (0x0000004c) 24-bit little-endian signed integer
Now audio is being sent directly to the device as 24-bit integers.

If the log indicates that audio is being sent as 16-bit integers we can troubleshoot further!

jgarshon
Posts: 3
Joined: Sun Jun 12, 2011 8:52 pm

Re: Decible forcing 16 bit depth on Nuforce HDP DAC

Post by jgarshon » Mon Jun 13, 2011 2:22 am

Thanks so much for the quick response. I wondered why 16 bit sounded so good?
it is a bit odd that the audio midi window keeps kicking back to 16 bit when it should show 24 bit as it does when I use pure music's app. Is Decibel bypassing the audio MIDI engine when exclusive access is turned on? Also, I have noticed another nice improvement in performance when selecting "load files in memory" in the preferences. The sound is richer and more detailed with quieter backgrounds. Very nice indeed.

Best regards,

JG

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