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Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Mon Dec 26, 2011 5:15 am
by SamS
Mac 10.6.8 Intel Core 2 Duo

When I play a 96/24 FLAC song in Decibel it changes my MIDI setting automatically to 16 bit even though I am using a 96/24 USB DAC recognized by the MIDI control panel - it refuses to use 24 bit for the USB FLAC files. It sounds like crap - harsh (truncation). The ability to play FLAC 96/24 files natively (w/o the complications of Pure Music) is the only reason I use Decibel - if it cannot do this properly I have no use for it (I have Pure Music, but (did) prefer Decibel for hi-res. Works fine via toslink out, only affects USB out.

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Mon Dec 26, 2011 8:34 pm
by sbooth
Do you have exclusive access enabled or disabled? Sometimes when exclusive access is enabled the sample rate reported by Audio MIDI Setup isn't reliable. Does Decibel display any status messages (at the bottom of the window) indicating your DAC's sample rate has changed? Also, is the "Automatically adjust sample rate" option enabled or disabled?

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Wed Feb 01, 2012 7:18 pm
by maru
I am having a similar issue.

In my case it is a little different though, spparently the physical stream gets set to 24BIT signed for 16BIT flac files. Here is the relevant output from the logs...

Feb 1 20:13:09 fordprefect.local Decibel[3907] <Info>: Creating decoder for "06 Far Away Eyes.flac"
Feb 1 20:13:09 fordprefect.local Decibel[3907] <Info>: Selecting physical format for stream 0x23: 2 ch, 44100 Hz, 'lpcm' (0x00000004) 24-bit little-endian signed integer, unpacked in 4 bytes lo

So it gets set to 24bit for some reason. But later on I see....

Feb 1 20:13:12 fordprefect.local Decibel[3907] <Info>: Decoding starting for "06 Far Away Eyes.flac"
Feb 1 20:13:12 fordprefect.local Decibel[3907] <Info>: Decoder format: 2 ch, 44100 Hz, 'lpcm' (0x0000002c) 16-bit little-endian signed integer, deinterleaved

So for some reason when opening the file the bitrate is set to 24-bit although it is then replayed with 16-bit.

I then tried to without "adjust sample rate"....

Feb 1 20:16:55 fordprefect.local Decibel[3925] <Info>: Creating decoder for "06 Far Away Eyes.flac"
Feb 1 20:16:55 fordprefect.local Decibel[3925] <Info>: Selecting physical format for stream 0x23: 2 ch, 44100 Hz, 'lpcm' (0x00000004) 24-bit little-endian signed integer, unpacked in 4 bytes low-aligned
Feb 1 20:16:55 fordprefect.local Decibel[3925] <Info>: Setting stream 0x23 physical format to: 2 ch, 44100 Hz, 'lpcm' (0x00000004) 24-bit little-endian signed integer, unpacked in 4 bytes low-aligned


Once again it is first set to 24BIT which I do not understand.

Kind regards,
Michael

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Wed Feb 01, 2012 11:45 pm
by sbooth
In your case the physical format is set to 24 bits likely because that is the only physical format the DAC supports. Most DACs only support a single physical format, typically 24 bits either packed or aligned in 32 bits.

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Thu Feb 02, 2012 8:33 am
by maru
sbooth wrote:In your case the physical format is set to 24 bits likely because that is the only physical format the DAC supports. Most DACs only support a single physical format, typically 24 bits either packed or aligned in 32 bits.
This is the internal audio of my Macbook PRO. And according to the audio midi program you can switch it to 16, 24 and 32bit.
This also happens when I have an external DAC connected via TOSLINK. In this case it also switches to 24bit.

It should be a non-issue though, but correct me if I am wrong Stephen. All that's happening is that I push 16bit down a 24bit link with no changes.

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Fri Feb 03, 2012 12:30 pm
by sbooth
It is a non-issue- as you pointed out converting 16 bits to 24 only involves a left shift. This physical format is chosen because when exclusive access is enabled Decibel will automatically select the integer output format with the greatest bit depth.

Re: Decibel Changes MIDI Setting to 16 for 24 Bit FLAC

Posted: Fri Feb 03, 2012 12:42 pm
by maru
sbooth wrote:It is a non-issue- as you pointed out converting 16 bits to 24 only involves a left shift. This physical format is chosen because when exclusive access is enabled Decibel will automatically select the integer output format with the greatest bit depth.
Just FYI, exclusive access was NOT enabled in this case, I checked that as well.