How does Airplay with AppleTV3 limit the subtleties??

[Ralf11]

or otherwise degrade SQ???

[mansr]

It's the SMPS, silly.

[Superdad]

It is well known that Airplay is not bit perfect.  Regardless of the source, it converts everything to ALAC and 16/48KHz.

 

Here is something written by the CTO of Roon Labs:

Oct '15

 

It looks like we always consider AirPlay to be “High Quality” as opposed to “Lossless”. Thinking back, I remember why.

There are two reasons for this:

• Many popular AirPlay devices perform internal format conversions that we know to be destructive (example: all AppleTV models convert 44.1k->48k).
• Since AirPlay streams are clocked at the source, they must either have fancy adjustable clock hardware that can conform to the stream coming from Roon, or they must perform DSP to resolve the clock discrepancy.

This second issue is slightly subtle. It’s our understanding that the vast majority AirPlay devices do not have the fancy clock chip that would be required for them to be truly bit-perfect, and instead modify the digital audio stream internally to resolve clocking discrepancies.

The AirPlay protocol gives us no way to know whether or not devices are committing either of these sins, so we’ve erred on the side of not attaching a false sense of sound quality to AirPlay devices as a whole.

 

And there was a whole thread on the topic here at CA:

 

 

And someone in Australia did some measurements:

https://www.stereo.net.au/forums/topic/74534-airplay-isnt-bit-perfect-proof/

 

[Cebolla]

10 hours ago, Superdad said:

It is well known that Airplay is not bit perfect.  Regardless of the source, it converts everything to ALAC and 16/48KHz.

 

Amazing misinformation -  this statement can be corrected if:

- you change "Airplay is not bit perfect" to "Airplay is not always bit perfect";

- you change "it" to "the AppleTV (version 2 & later)";

- and you remove the "ALAC and" bit.

 

Any resampling to 16/48kHz is an AppleTV issue, presumably in keeping with the standard resolution for audio in video broadcasts - so not strictly anything to do with AirPlay itself.

 

AirPlay's actual ALAC stream is always at a resolution of 16/44.1kHz.

[Cebolla]

 

Is that subtleties or subtitles?

[Superdad]

6 hours ago, Cebolla said:

Amazing misinformation -  this statement can be corrected if:

- you change "Airplay is not bit perfect" to "Airplay is not always bit perfect";

- you change "it" to "the AppleTV (version 2 & later)";

- and you remove the "ALAC and" bit.

...

AirPlay's actual ALAC stream is always at a resolution of 16/44.1kHz.

 

I guess I should have qualified my statement, though in fairness the OP did title this thread about the AppleTV.  

I know full well that, unlike the AppleTV, the Airport Expess does not convert everything to 16/48.  But it does convert everything to 16/44–and then transports as an ALAC stream.

So I pretty much stand by what I said.  

 

Apple could have achieved hegemony in the market with Airplay, but they blew it years ago by putting up barriers (licensing, legal, and technical) to third-party adoption.

 

I enjoy my modified (ripped out internal SMPS to run from external 3.3V LPS) Airport Express out in our shop building, but IMHO it has no place in a high-end music system.

[wgscott]

A few points possibly worth considering:

 

1. Airplay forces sampling to 44.1 kHz.

2. ATV forces sampling to 48 kHz.

3. Apple TV can play a 16 bit, 48kHz music track bit-perfectly if you avoid airplay and instead use the ATV interface itself.

4. I've never seen a clear explanation if output is restricted to 16 (vs 24) bit.  (The two choices given in the ATV interface are 16 bit and automatic).

5. Even with double-resampling, I have not detected an audible degradation in sound quality.

6. Playback is gapless, which matters to me more than inaudible resampling artifacts.

[Ralf11]

At any rate, thank you Superdad for your responses.

 

First, my setup sounds just fine and accords with Bill's comment re SQ.  I am inclined to do some testing tho...

 

You have introduced 3 lines of evidence:

 

1. Roon's comments

2. old thread here

3. Australian thread

 

The Australian thread comes down to merely a warmer sound - and apparently on on a TV2, not TV3.  The treble drop off is certainly less than many speakers too.  I agree no freq. range reductions are best tho.

 

The old thread here also relates to a TV2 and I made some comments on that thread bumping it up.  There is more RAM (of the same type) and a faster processor in the TV3, tho it is not clear those changes matter to SQ.  There may be other changes as well, and some have commented on SQ differences.

 

The Roon comments are in 2 areas: one is the claimed "destructive" rate conversion.  He does not say what is being "destroyed" either.  There is an old thread on this here and without more on how this upsampling damages SQ I regard it as a red herring.  Measurements and/or listening tests are also lacking.

 

The second issue raised by the Roon quote is clocking.  I am curious about that one.

 

Your use of "well known etc." is really not supported at all.  But you have made me a little suspicious of the TV3, so I think I'll do a direct comparison with my Mac Mini feeding into the same DAC, tho not using the same interface unfortunately.