Upsampling MQA files to original resolution with sox will sound like the original resolution

[Don Hills]

Soxr,

If I have read your description correctly, you are taking the distributed MQA file (24/44.1, with noise in the lowest 8 bits) and upsampling it to the original resolution with a minimum phase filter. I can appreciate that this would sound very similar to the original, similar to downsampling to 16/44.1 and back up again. 

What do you think the results would be of first passing the MQA file through the MQA Core decoder to retrieve the content encoded in the lowest 8 bits, before upsampling?

[Don Hills]

9 hours ago, soxr said:

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I don't believe their deblur processing is already applied to the 24/44.1 or 24/48 distribution file, but encoded as a metadata field, which sets the correct post processing filter in the renderer.

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That makes sense. Although they say they have a process to apply MQA at the A to D stage, all of the MQA content that I am aware of is previously released. In many cases there's no single ADC stage that can be identified for "deblurring".

 

The only concern is the performance of the filter MQA uses to split the signal into 0-22 and 22-44 KHz bands when encoding. Because the splitting and joining filters are intended to be complementary, the performance of the splitting filter on its own may be less than optimum. Ignoring the ultrasonic aspect, it may still be worthwhile to do the rejoining to remove the effects of the filter in the audible range.