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RE: Charles, Please tell me if this makes sense.

OK, I'll answer my own question: It does make sense--at least I think it does. Is it correct? No idea, but it makes sense.

I don't remember what the MQA patent application says--I found that hard going and, like most patent applications, absurdly repetitive: sentence after sentence saying the same thing, or almost the same thing with minor (if important) variations. However, that JAES conference proceeding that outlines the MQA approach (without ever mentioning those three letters) is completely clear about the two families of MQA files, 44.1 and 48. One is not converted into the other; they remain separate. "We thus have recipes for downward and upward conversion within a hierarchy of rates such as 44.1, 88.2, 176.4 and 352.8 kHz, however these methods do not provide satisfactory conversion from, for example, 96 kHz to 88.2 kHz." They go on to give a recipe for converting, eg, 192 to 176.4, but it's clear they think such a procedure would not be satisfactory at lower sampling rates.

When fully decoded, the Beyonce track plays back at 44.1/24.

What, then, is the content above 22kHz? Again, I don't know, but this makes sense: There's a mirror image of any signal above Nyquist, unless it's filtered. MQA has a slow roll-off filter. (I should check back and remind myself HOW slow it is, but I'm too lazy to do that.) So, the image above Nyquist is attenuated but not suppressed. You'r seeing the attenuated image.

Given all that--and considering that, as the CD spectrum shows, the Beyonce track is brick-walled at about 21kHz--this is just what I'd expect to see.

What "bug" are you referring to?

Best,
Jim

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