Article: Apple Music Lossless Mess Part 2: AirPlay

[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:

[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.

[pkane2001]

32 minutes ago, Jud said:

 

That would all be fine if Apple wasn't selling the service as high resolution music, implying it's better.

 

Chris isn't saying we've all got golden ears, he's asking for truth in advertising.

I’m not sure that Apple is lying. They provide high resolution music that’s at higher sampling rate than the CD and with more than 16 bits. They provide up to 23 bits out of 24 based on my testing. While it’s not bit-perfect, it is certainly high resolution and not lossy-compressed… at least up to 23 bits.

[pkane2001]

Just now, Jud said:

 

Some clever marketing staffer could give it the slogan, "Not your ordinary high resolution music!" 😉

Or ‘improved hires’? I think I’m ready to go into marketing.

[pkane2001]

8 minutes ago, The Computer Audiophile said:

This is why I went down this road. Without looking into it, one has no clue if it’s MP3 or ALAC or where some DSP is taking place. 

Absolutely. I’ve had an Apple Music subscription for a long time, but rarely listened to it, preferring my own music library that I knew was properly sourced and encoded, and not damaged in some way. Apple lossless and hires seem to be moving things in the right direction, even if not bit-perfect. I’m still not sure what their Masters recording is supposed to be compared to hires.