10-Sep-2014, 12:10
(10-Sep-2014, 09:40)thumb5 Wrote: One key difference between AIR and AES/EBU (as I understand it, please correct me if I'm wrong) is that with AES/EBU, the source (e.g. Totaldac d1) encodes the data stream using its own clock and the Devialet has to extract the clock from the data stream. I'd assume it then has to either drive its own audio playback pipeline completely from the recovered clock, or somehow re-clock/re-sample the data to synchronise it with its own internally-generated clock. For what it's worth, my guess is the latter case. Although the two clocks should of course be nominally running at the same rate, over a long-enough time they will necessarily drift because neither of them can be completely accurate/stable. This clock synchronisation process might introduce subtle changes to the data stream - who knows?
Another factor is that the AES/EBU interface has limited error detection but essentially no mechanism for error correction. These AES/EBU guidelines suggest in section 3.8 that a DAC detecting errors in an AES/EBU input stream should handle them by interpolating between valid samples, or by muting its output. Needless to say, neither of these can be considered "bit perfect" activities. I've also seen this referred to as "error concealment" rather than error correction.
Hello thumb5
This is very interesting. Then it is hard to imagine how using two clocks in a row could produce a better sound than using only one since the beginning of the process.
thumb5 Wrote:As always, subjective judgements of sound quality can and should continue independent of the technical discussion...
Agree
