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Article: Apple Music Lossless Mess Part 2: AirPlay


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49 minutes ago, Jud said:

Apple is just "zero padding"?

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.

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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.

shifted noise.jpg

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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)

 

24bit sad stuff.jpg

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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.

 

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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:

image.png

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.

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