Does software player matter if using digital outputs? (HDMI or Hifiberry DIGI+)

[adixor]

Hi guys

 

I am making my first steps in (PI-based) HIFI but after having read through many forums and links, I still have a question: does a software player (whatever comes with any of the PI distributions around, volumio, runeaudio, moode, osmc, etc) matter when playing say flac files via digital outputs? (built in HDMI or via Hifiberry DIGI+). Because I can't imagine how the player would change this digital playing much though I do understand how a DAC, speakers, cables, etc would change that.

 

I need this to decide if I should stick to OSMC (that I use for video) also for music or to have a separate headless PI with one of the audio distributions around if there's good reason to believe playing from those is better (audible).

 

p.s. I could not arrange yet an A/B test as I have just ordered speakers and will take some time to get them, but also I don't think my ear is very sensitive to small differences in audio so asking the community for help.

 

p.s2: final setup: hifiberry digi+ -> digital coax -> yamaha s501 stereo amp -> b&w cm5 s2

 

Thanks

Adrian

[Keith_W]

Depends on whom you ask. The authors of Jriver and Foobar and some bloggers like Archimago say that all bit perfect players* will sound identical. Most people on this forum will tell you that their particular flavour of player sounds better.

 

* Note that some players are not bit perfect, in that they apply DSP to the signal before digital output - such as HQPlayer. To my ears, HQPlayer easily sounds better than other players, particularly with room correction and other DSP applied.

[adixor]

Depends on whom you ask. The authors of Jriver and Foobar and some bloggers like Archimago say that all bit perfect players* will sound identical. Most people on this forum will tell you that their particular flavour of player sounds better.

 

* Note that some players are not bit perfect, in that they apply DSP to the signal before digital output - such as HQPlayer. To my ears, HQPlayer easily sounds better than other players, particularly with room correction and other DSP applied.

 

Thanks Keith. I had hoped this is not as debated as it seems is. However, I would not use other DSPs, just want the player to be as ... transparent ... as possible if that's a good word here. Any audiophiles that are using OSMC successfully?

[ecwl]

As Keith says, it depends on whom you ask. For those like myself who believe the software can matter, perhaps it's better to explain why.

If you're using an electrical digital output, some RF noise is going to be buried within the digital signal and the noise will affect the performance of the DAC to some degree. How much will depend on the degree of galvanic isolation that is present in the input of the DAC and the overall DAC design. By changing the software you're using, you're inevitably altering the degree of RF noise. So that's one reason why the sound maybe affected.

The second reason why the sound maybe affected is that different DACs have different jitter tolerances and they handle jitter differently. The software player would inevitably alter the degree of jitter that is in the incoming signal and depending on how the DAC handles the signal, it would alter the final output jitter in the analog sound. This is the reason why even if you're to use Toslink and electrically isolate the signal between the computer and the DAC, the software can still potentially affect the sound.

Ultimately, these things are computer and DAC dependent and it also depends on whether people believe these issues with RF in the digital signal and jitter in the digital signal and analog outputs are audible. Some people feel strongly that we have a great understanding of the threshold of audibility so none of these things I'm describing are actually audible. This is because they believe that any competently designed DACs would have good enough galvanic isolation to filter RF noise and would have a low enough jitter tolerance and in turn sufficiently low jitter on the analog output that any changes to the software would be completely inaudible. If you believe that, then software players should not matter. But then if you think that, why aren't we listening to music exclusively through iPhones?

Anyway, this type of controversy has been discussed on multiple forum posts in the past. Let's hope this one is not going to cause another massive debate. If you hear a difference from different software players, then pick the sound you like. If you don't hear a difference, great for you.

[The Computer Audiophile]

A couple sensible answers. Thanks guys :~)

[adixor]

Anyway, this type of controversy has been discussed on multiple forum posts in the past. Let's hope this one is not going to cause another massive debate. If you hear a difference from different software players, then pick the sound you like. If you don't hear a difference, great for you.

 

I certainly would not want to start a controversy and I do understand now the different point of views (did not think that the software implementation could cause jitter on the digital outs, and to be honest, if this is caused by the internal CPU scheduling - the only thing that comes to mind - as long as the OS is not realtime, then I can't see how _any_ app would be able to work around this). So what's left to find out is if people do hear differences between OSMC and MPD-based solutions. I could only find one guy in a forum saying that he tested these and OSMC "didn't sound great" (or something like that) in comparison. I feel that I'm gonna have to test it myself to see if there is any difference I can identify.

 

Thanks for the reply!

[mansr]

I certainly would not want to start a controversy and I do understand now the different point of views (did not think that the software implementation could cause jitter on the digital outs, and to be honest, if this is caused by the internal CPU scheduling - the only thing that comes to mind - as long as the OS is not realtime, then I can't see how _any_ app would be able to work around this). So what's left to find out is if people do hear differences between OSMC and MPD-based solutions. I could only find one guy in a forum saying that he tested these and OSMC "didn't sound great" (or something like that) in comparison. I feel that I'm gonna have to test it myself to see if there is any difference I can identify.

 

Thanks for the reply!

The timing of outgoing bits/packets is governed by hardware using crystal oscillators. No software, not even the OS, has any influence at that level. While it is conceivable that different software might cause different noise profiles emanating from the CPU, which in turn would distort the S/PDIF or USB clocks resulting in jitter, the extent of this is tiny. Moreover, audio playback presents so light a load as to be mostly indistinguishable from an idle system if we're dealing about regular Mac or Windows computers. To then start talking about audible differences between players strikes me as ridiculous.

 

Analogue outputs are another story. Cheap built-in sound cards can certainly pick up audible noise from other system components.

[Jud]

The timing of outgoing bits/packets is governed by hardware using crystal oscillators. No software, not even the OS, has any influence at that level. While it is conceivable that different software might cause different noise profiles emanating from the CPU, which in turn would distort the S/PDIF or USB clocks resulting in jitter, the extent of this is tiny. Moreover, audio playback presents so light a load as to be mostly indistinguishable from an idle system if we're dealing about regular Mac or Windows computers. To then start talking about audible differences between players strikes me as ridiculous.

 

At least one player was open source for quite a while (Audirvana before Plus), so anyone could have checked out exactly what it was doing, but apparently no one bothered.

[adixor]

At least one player was open source for quite a while (Audirvana before Plus), so anyone could have checked out exactly what it was doing, but apparently no one bothered.

 

MPD is open source isn't it? Though this doesn't really help me as I wouldn't know what to do with the sources

[mansr]

At least one player was open source for quite a while (Audirvana before Plus), so anyone could have checked out exactly what it was doing, but apparently no one bothered.

There are many open source audio players. More importantly, the Linux drivers are always open source. If you study them, you'll see that there's precious little an application can do affect the timing of the output.

[Miska]

I would recommend to stay away from HDMI as audio transport. HDMI audio has been added as ugly afterthought on top of DVI standard. It has clocking based on the video pixel clock and the bandwidth available for audio depends on the selected video resolution. So your jitter performance etc will vary depending on combination of video settings and audio setting. Later revisions have added asynchronous feedback support for audio, but it is not really good because of tight synchronization requirements between video and audio (obviously important for movies and such).

 

While S/PDIF has it's own deficiencies, receivers have been under development for decades and best ones tend to perform very well, sometimes better than USB implementations.

[Jud]

There are many open source audio players. More importantly, the Linux drivers are always open source. If you study them, you'll see that there's precious little an application can do affect the timing of the output.

 

Can do, or these applications have done?