MQA: the folding stuff

摘要

Writing about the 50th anniversary release of The Doors' Waiting For The Sun [HFN Oct '18], Steve Harris mentioned that it included CDs that 'come with MQA encoding'. He then said that 'The CD tracks are encoded so that when played back through an MQA decoder, the data can be "unfolded" up to a higher sample rate. They'll also play back normally on a standard CD player. In other words, MQA is backward compatible with normal Red Book CD'. I don't think this is possible. The only music data format, if you like, that a Red Book CD and hence the associated CD player is able to support is 44.1kHz/16-bit linear PCM. Any music data that is encoded differently simply doesn't adhere to the Red Book standard. Therefore, 'unfolding' to a higher sample rate would be impossible using a CD encoded according to the Red Book standard. It would be possible to include MQA-encoded data in the 16-bit 'words', but those 16-bit 'words' would no longer be 16-bit, linear PCM. Would you agree?