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WiMP comes to the UK/US as Tidal


Grahame
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I read a couple paragraphs beyond the first paragraph, so not much more. From what I read, you must have a DAC with the special decoder to hear an MQA file the way it was intended. Otherwise, it is just a 24-bit 48kHz file with noise on the 3 LSB, lowering effective resolution to 13 bits. The MQA file decoded claims to have "folded" into it the upper 48kHz I believe, so generates something akin to 24/96 (lossy). There is also some other metadata which tells the DAC what filters to use on the fly and maybe some other stuff, with some typical mention of the pre-ringing/apodizing stuff that Meridian love to talk about, and something about proprietary sampling/convolution. 

I just found this article after I wrote above post, have not read it yet but the title is pretty much as expected: https://benchmarkmedia.com/blogs/application_notes/163302855-is-mqa-doa

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2 minutes ago, mypasswordis said:

From what I read, you must have a DAC with the special decoder to hear an MQA file the way it was intended.

Tidal has the MQA software decoder built in so it is able to "unfold" the file.

The next version of Audirvana will have it also.

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Does anyone know if there's a way to figure out what bitrates are going to the DAC on a Windows computer?

Listening to Black Sabbath now.  From memory (several months), it sounds a little less harsh, but that's from memory, it's going to require some contortions to find my downloads, which got lost and not restored when I switched computers.  (Because I found them too harsh to listen to repeatedly.)

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Best I can tell from the Roon forum, some streamer apps (including Roon) can pass the MQA stream though to an MQA DAC. Some apps (Tidal, and soon several others, including Roon) can our will eventually be able to transcode the stream to whatever resolution it represents. But i can't see how the matching filter thing could be implemented for an arbitrary DAC. If so, software decoding won't be able to provide the "complete" MQA expense.

So, for me, it's "95% of 95%", whenever I can figure out the logistics of getting the signal to the DAC in the system I actually want to use it in.

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Meanwhile ...

HIGHRESAUDIO TO STOP OFFERING MQA

Online music provider to drop MQA, claiming format 'not lossless'

Via: http://www.hifiplus.com/articles/highresaudio-to-stop-offering-mqa/

Technical analysis paper https://www.xivero.com/blog/hypothesis-paper-to-support-a-deeper-technical-analysis-of-mqa-by-mqa-limited/

Conclusion / Summary points
1) MQA is in fact “lossy” because it alters the bit-depth and frequency response (magnitude & phase) and therefore time domain appearance of the original high resolution audio file by applying none-linear-phase filters impacting the critical audio spectrum (e.g. 4dB attenuation at 40kHz).

2) An alternative compression scheme that does not show those adverse effects has been described above and can be used for streaming applications or mobile high resolution audio players, with limited memory, to store at least 40% more audio files.

Discuss

Edited by Grahame
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