Addicted to Fun and Learning
- May 30, 2021
- Waltham, MA, USA
Good Explanation, understood.[edit: I have been making it sound like the decoder does this upsampling. Seems to make more sense to me that they would add the mirrored ultrasonics using the same technique but prior to or part of the encoding process. Then the decoder can treat these like other MQA files]
I'm pretty sure you are clear on this, but just so it is clear, this has nothing to do with the 2nd unfolding. The point made by @Werner is that when MQA files are made from 24/44 originals, the decoder (1st unfold) automatically upsamples with a weak filter to produce that mirroring. This gives the appearance of ultrasonics but since there were none to begin with I would call them fake.
Anyone can do the same. Here is what I get when I upsample a 44Khz version of the track using no filter (so worse than what MQA does):
View attachment 134088