Article: Apple Music Lossless Mess Part 2: AirPlay

[James lee]

Listen for quieter parts in busier sections. You can sense the depth more of the quiter elements.

[The Computer Audiophile]

2 minutes ago, James lee said:

It's not zero. I cant tell you exactly what is in bit 24 but it is something.

DRM / watermarking?

 

 

[James lee]

I shifted the 24bit "thing"(removed 24bit from Apple Music 16bit lossless stream) up 16bits with a pure bitshiftgain plugin from airwindows.

the thing shows now on the 8th bit and is loud enough to scope with izotope.

It appears to be just a random noise... see pic.

the data might mean something to someone but to me seems like just randomish noise, a bit stereo but not total wide like real random noise would be.

[James lee]

My guess is it's and unintentional bug left over from AAC playback where the decoder would need to dither to 24bit or also the Atmos/spacial coding needs a dither also.

That would be just a Doh from Apple

[James lee]

ok. 24bit did as expected 🤕 noise is added.

Attempts to null with known lossless shows the dirty bit but this bit also contains the last bit of the music.

So any truncation attempt at say 23rd bit will result in quantization distortion.

The picture below is of this 24th bit with all else nulled away, you can see the music in the spectogram. (there is a keyboard hook on the left then a drop on the right - Deadmau5)

 

[Jud]

6 hours ago, James lee said:

It's not zero. I cant tell you exactly what is in bit 24 but it is something. Waves IDR can choose 22bit, 18bit as well as 16bit/24bit. All except 24bit fixes the stream.

I've done blind test as randomised 5 round test. So far only two rounds. I picked Qobuz 60percent of the time each bunch.

 

A bit (heh) puzzled. Are you saying you're able to hear content in the 24th bit (-144dB) at a 60% rate, or something quite different?

[pkane2001]

5 hours ago, James lee said:

ok. 24bit did as expected 🤕 noise is added.

Attempts to null with known lossless shows the dirty bit but this bit also contains the last bit of the music.

So any truncation attempt at say 23rd bit will result in quantization distortion.

The picture below is of this 24th bit with all else nulled away, you can see the music in the spectogram. (there is a keyboard hook on the left then a drop on the right - Deadmau5)

 

 

That last bit appears to be modulated by low frequency "noise", which I'm guessing, contains watermark data spread out to look like noise:

[The Computer Audiophile]

Just an FYI, I've reached out to Apple seeking comment and a contact for technical questions. 

[James lee]

4 hours ago, Jud said:

 

A bit (heh) puzzled. Are you saying you're able to hear content in the 24th bit (-144dB) at a 60% rate, or something quite different?

I can't hear the added noise. I can hear more of the original preserved if the noise is not present. In two blind tests 60percent of the time.

A third longer test 66percent of the time.

In a fourth test I failed at 40percent. That track was almost entirely mono and I'm putting my hunch on stereo imaging as one tell-tale ways to see into the finer aspects of this difference.

 

[The Computer Audiophile]

If anyone is interested in how watermarking has been used in the past with Universal content on Spotify, this is interesting. 

 

https://www.mattmontag.com/music/universals-audible-watermark

 

[James lee]

1 hour ago, pkane2001 said:

 

That last bit appears to be modulated by low frequency "noise", which I'm guessing, contains watermark data spread out to look like noise:

I don't see this noise in my last bit null tests on 16bit AM streams. I have seen spikes like this even in Qobuz and it seems to be either old tec errors that were missed back in the day or some other reason.

[pkane2001]

10 minutes ago, James lee said:

I don't see this noise in my last bit null tests on 16bit AM streams. I have seen spikes like this even in Qobuz and it seems to be either old tec errors that were missed back in the day or some other reason.

 

That was found in multiple Apple Music streams, from lossless to hi-res when compared to the original track. The signal at around 20Hz was certainly not there in the original, but was introduced by Apple, intentionally or unintentionally. I know of no good reason to modulate music at around that frequency by modifying the least significant bit, other than trying to encode something in the music that's below perception and not easily detected.

[iamoneagain]

Have you tested the IOS 15 beta yet? I’m pretty sure it’s now lossless over AirPlay 2 but this is only based off listening tests. Also streaming to Naim streamers, there are album art display issues systemwide from IOS 15 no matter what streaming app. Usually no album art but occasionally it shows up. And there can be a little bit of stuttering when first starting or switching between high quality and lossless in the settings. 

[Marco Klobas]

11 hours ago, iamoneagain said:

Have you tested the IOS 15 beta yet?

 

It seems that nothing has changed: https://community.roonlabs.com/t/apple-music-high-res/159869/1249

 

 

[Bevok]

Introducing lossless to Airplay 2 with its multiple speaker support is certainly a big call with a lot of headwind in getting this to work robustly on wireless networks or Internet connections with a lot of latency or lack of bandwidth. I think it will be a while coming or have to use some kind of adaptive resolution ala Netflix rather than a straightforward bitperfect Alac. Not stating lossless support for Airplay in the official information and streaming AAC to airplay 2 devices may be quite intentional. A good robust listening experience I’m sure will be Apple’s number one priority. 

 

That said I’m a bit confused by that Roon forum post as although the Cambridge reports AAC it also says 16/44.1 (ie CD quality lossless) which is also what my Apple TV streams that album at (sounds wonderful by the way!).

[The Computer Audiophile]

7 hours ago, Bevok said:

Introducing lossless to Airplay 2 with its multiple speaker support is certainly a big call with a lot of headwind in getting this to work robustly on wireless networks or Internet connections with a lot of latency or lack of bandwidth. I think it will be a while coming or have to use some kind of adaptive resolution ala Netflix rather than a straightforward bitperfect Alac. Not stating lossless support for Airplay in the official information and streaming AAC to airplay 2 devices may be quite intentional. A good robust listening experience I’m sure will be Apple’s number one priority. 

 

That said I’m a bit confused by that Roon forum post as although the Cambridge reports AAC it also says 16/44.1 (ie CD quality lossless) which is also what my Apple TV streams that album at (sounds wonderful by the way!).

16/44.1 is the sample rate and has nothing to do with lossy or lossless. MP3 and WAV can be 16/44.1. 

[R1200CL]

So is this showing in video bit perfect or not ? 

I think not  (Is really Darko that stupid?)

 

6. Apple's Music App, lossless streaming content, USB output with CCK - not bit perfect at 44.1.

7. Qobuz, lossless streaming content, USB output with CCK - bit perfect at 44.1 and 192.

 

What about Tidal and CCK ?

 

 

[Bevok]

I don’t think Darko says anything about bit perfect?

[Marco Klobas]

Indeed.

 

The same video was shared on Roon forum and I replied that he showed the sample rate matching which is automatic on iOS and iPadOS.

 

The bit perfect issue isn't covered.

 

Moreover he claimed two times that 48 kHz is possible via AirPlay which isn’t true for audio only streams.

[The Computer Audiophile]

It bears repeating that sample rate has nothing to do with lossless or bit perfect playback. MP3 can be 44.1, just like WAV, FLAC, and ALAC. 

[R1200CL]

[actuel audio]

19 hours ago, Marco Klobas said:

 

Moreover he claimed two times that 48 kHz is possible via AirPlay which isn’t true for audio only streams.

I think some of the confusion in speaking about this topic, easily for anyone to make, is that the prefs for AM Lossless show it as up to 24/48. So, the MacOS or iOS will knock that down to 16/44.1 if it is sending to Airplay. Nobody will notice that at all.

I think Apple segregated Lossless from Hi-Res because most Apple users have no idea what a DAC is and have little understanding. Also, Apple TV is 48.
This is a non issue. If you know what a DAC is and have one and like Hi-Res, set it higher. If you are listing to 95% of the music made, most of which is pre digital or is badly edited and engineered as to be a whopping 6 bits, then 24/48 via DAC or Airplay will be fantastic. Set it and forget it no matter how you hear it.
As far as bit perfect from a Mac, my understanding is that if the Audio MIDI Setup is set to the same as the source, then it is bit perfect to a DAC. A PITA for sure. Hopefully this gets updated with soon to be new Mac OS update. On iOS, it is automatic.

 

[The Computer Audiophile]

23 minutes ago, actuel audio said:

As far as bit perfect from a Mac, my understanding is that if the Audio MIDI Setup is set to the same as the source, then it is bit perfect to a DAC.

No, see this - 

 

 

[Phil C]

Whew! Thanks for all this hard work Chris!

[James lee]

This is my summary of the ios 16bit lossless fix.