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HWTest · 2012-12-27, 19:33

I'm suspecting XBMC, that it lowers the bit depth of hi-res audio file from 24 to 16 bit.
My setup - Xtreamer Ultra 2, OE 2.0.0, hw:0,1, optical output.
My receiver displays only the sampling frequency of the input signal but not the bit depth.
To test this, I've created a 24/44,1 audio file (FLAC) and while playing tried to record directly from the optical output to a DAT recorder, which accepts only
16/44,1 and 16/48 signals. The recording was OK.
My conclusion from that test is, that XBMC reduces the bit depth from 24 to 16 bit - that is not bit perfect!
Is there a way to display in OE the audio output format from the file actually playing?
How to setup OE, that it doesn't reduce the bit depth.

Mitch23 · 2012-12-27, 21:16

OE 2.0.0 does not suppert HD-Audio. You could try OE 2.95.6. This includes the new audio engine.

DDDamian · 2012-12-28, 08:28

Something got broken over the last month where the volume level can get dropped from 100% and not rise again despite what the GUI says - this is messing with bitperfect as seen with HDCD playback, which reveals any changed data in the lower bits. If you're not seeing an HDCD indicator on HDCD encoded material. This seems to have happened around B1 or B2 - looking into it.

@HWTest - if your system supports 24bit you get 24bit, including with mp3 which have no natural bitdepth.

HWTest · (This post was last modified: 2012-12-28, 19:55 by HWTest.)

(2012-12-28, 08:29)DDDamian Wrote: @HWTest - if your system supports 24bit you get 24bit, including with mp3s which have no natural bitdepth.

What do you mean with "system"?
Xtreamer Ultra 2?
OpenELEC ?
My receiver?

(2012-12-27, 21:16)Mitch23 Wrote: OE 2.0.0 does not suppert HD-Audio. You could try OE 2.95.6. This includes the new audio engine.

I know it doesn't support HD-Audio - I think that means it doesn't support DTS-HD, DTS-MA, DD-TrueHD.
But it supports DTS 24/96 - I've tested it.
The receiver displays DTS 96/24 but the signal info on the receiver OSD shows sampling frequency 48kHz - I'm puzzled
And 24/xx files are reduced to 16/xx ?

DDDamian · 2012-12-28, 21:38

By system I mean everything after we pass the audio data off - so your driver, OS or audio API (like ALSA), physical link (optical, hdmi, analog) and receiver.

This applies only to AE builds (pre-Frodo). If you are using Eden then yes, it will be 16bit.

HWTest · 2012-12-29, 00:55

OK, I have OE 2.0.0 (Eden), so 16bit no matter what.
When I upgrade to OE 2.95.6 (Frodo), the 24bit should work (supposed my system supports it, I think it does)?

Is there a way to find out that my system outputs 24bit?
I've found out the DAT recorder test is not conclusive. I've tried recording from the optical output from a PC, changing the output bit depth from 24 to 16 and back and as long as the samplerate was 44,1 or 48 the DAT recorder recorded without a problem. It looks it somehow "ignores" the additional 8bits ...

DDDamian · 2012-12-29, 04:49

Over optical the most likely is 16/48 and 16/44.1. Yes, the extra bits are likely dropped. HDMI is your best bet for higher bitrates/depths. That or possibly a USB DAC.

HWTest · (This post was last modified: 2012-12-29, 07:25 by HWTest.)

My receiver is capable on optical/coaxial up to 24/192 - tested with a PC and I have an external DAC (Arcam rLink) also capable on optical/coaxial up to 24/192, which I would like to use for music.

Krobar · (This post was last modified: 2012-12-29, 12:08 by Krobar.)

No luck with Frodo RC2 on XBMCBuntu either; I just get digital noise for DTS CD files which means it isnt bit perfect. Is there any thing that needs to be adjusted in the settings or mixer to get bit perfect playback?

DDDamian · 2012-12-31, 23:47

DTS CD plays back fine here in a .wav container - is your volume set to 100%?

villeneuve · 2013-01-03, 00:48

DTS in wav-file is fine here, too. But trying to play a DTS-encoded Audio CD XBMC just skips through all the tracks on the CD in a few seconds with no tone played, not even a static noise.

ian-ep · 2013-01-04, 17:56

Does anyone know the situation with regard to bit-perfect stereo audio over USB?

I have a Cambridge StreamMagic 6 which contains a USB audio 2.0 (asynch) DAC capable of 24/192 (same DAC as the DacMagic plus). It works fine with spdif (optical) up to 24/192 from my Asrock ION 330HT running the latest Openelec beta with Frodo. However, I can almost never get xbmc to recognize the StreamMagic as a USB DAC. It simply doesn't appear as an option. I say 'almost never' as I have succeeded a couple of times getting the DAC to appear in the options a couple of betas ago, but it disappeared again after a reboot. So it obviously can be done ... but how to make it stick?

It worked flawlessly in Eden with a custom audio setting of 'plughw:2,1', but the custom option has mysteriously been removed in Frodo, so ...

Any suggestions?

Ian

DDDamian · 2013-01-05, 04:24

@villeneuve - never tried with physical media - why not rip them? That's part of what XBMC is about (HTPC's / media servers).

@ian-ep - I'm not a Linux guy, but there was some code recently merged to show a wider range of devices in Linux, just not sure if it's in current OpenElec builds. It may help in your case.

**Martijn** · 2013-01-05, 04:41

(2013-01-05, 04:24)DDDamian Wrote: @villeneuve - never tried with physical media - why not rip them? That's part of what XBMC is about (HTPC's / media servers).

@ian-ep - I'm not a Linux guy, but there was some code recently merged to show a wider range of devices in Linux, just not sure if it's in current OpenElec builds. It may help in your case.

Yes it is in openelec

JBNY · 2013-01-06, 02:10

Two questions or issues with AE right now. I have a few devices that seem top work well with XBMC for audiophile use. A Wyred 4 Sound DAC2, Audioquest Dragonfly, and a Musical fidelity VLINK192. All seem to exhibit the same behavior using openelec RC1.

ReplayGain is not working working correctly. FLAC files play a few decibels louder than MP3, Flac files all play the same volume, 44.1 through 192, but the mp3 files all play at a lower volume, both in album and per track. when using a playlist with both file formats it is quite apparent.

Crossfading studders when XBMC encounters files of mixed resolution, 96k to 44.1k or 48k, maybe the solution is to not mix them if they are different resolutions like jriver media does?