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Clarification

>>If you play a Tidal Master and do not have software decoding enabled it is still delivering a high quality 24/48 stream.... which is better than CD quality.<<

Actually this is not the case. MQA is delivered in a 48/24 FLAC container. However the seven or eight Least Significant Bits (LSBs) of the container are used to store the "folded" dual-rate audio data (encoded losslessly) and the quad-rate audio data (encoded with lossy compression). They *replace* the low-level bits in the original 24-bit file. reducing the resolution of MQA below 24 bits.

If one starts with a full 192/24 true high-res source file, MQA encoding/decoding allows three possibilities:

1) Hardware decoding of MQA can perform both unfolds. The result is 192 kHz sampling rate but with a resolution of something less than 17.2 bits maximum. It appears that the number of lower bits required to store the dual- and quad-rate information is dependent on the signal levels in those upper bands. The MQS AES paper specifies that program material of a string quartet results in only 17.2 bits of resolution after the first unfolding (dual-rate source).

However according to James Boyk of Caltech, the string family (violin, viola, cello) has the lowest amount of signal power above 20 kHz than any other orchestral instrument besides an oboe. Boyk's article measures cymbals as having 30 dB (1000x) more power than a violin. Without further information it seems that the baseband audio resolution could be reduced as much as 6 bits fewer than the example of the string quartet.

2) If using a non-MQA DAC, the Tidal app allows for a single unfold via software, delivering up to 96 kHz sample rates, but again the resolution is still limited to a maximum of 17.2 bits (depending on the levels of high-frequency energy in the track).

3) If no decoding is used the 192/24 source file will be delivered with at a 48 kHz sampling rate, again with a maximum of 17.2 bits (depending on the levels of high-frequency energy in the track). For the published example of a string quartet, this potentially about 1 extra bit over Redbook. It is unknown at this time, but possible that music with high levels of high-frequency energy (eg, lots of cymbals, percussion, synthesizer, even brass or piano) would have *less* than 16 bits of resolution in the baseband - possibly even as low as 11 bits.


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