In Reply to: RE: Are you saying that 1-bit DSD and PCM sigma delta conversion are the same? posted by tailspn on July 19, 2017 at 05:35:52:
But, as I read it, I think that your differences with what John wrote seem to lie in what each of you thinks is lost when going from DSD to PCM.
When John says:Conversion from 1-bit DSD to multi-bit PCM is a lossless process inside the audio band. The only thing that is removed is the out-of-band noise above the Nyquist limit of the PCM system. Nothing else is lost. . .And you say:
Conversion from multi-bit PCM to 1-bit DSD is always a lossy process. The loss is due to the 1-bit truncation. This truncation introduces a very large ultrasonic error signal that makes the ultrasonic region unusable for audio.If PCM is desired/required, then these PDM bitstreams (1 to 8 typically) are then followed by low pass filtering (decimation) and conversion to parallel X-bit wide Pulse Code Modulation binary words. That latter process is most certainly a lossy process. Once decimation filtered, you can no longer reconstruct the original PDM (DSD if 1-bit) bit stream.
So. . . as I read this, I conclude that you're definitely removing SOMETHING in going from DSD to PCM. But what is it? Is it the out-of-band noise and nothing else, as John seems to suggest? I mean, in a way, you guys are kind of saying the same thing. Right?
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Tom - I appreciate your indulgence in responding so thoughtfully to my posts - Chris from Lafayette 10:51:04 07/19/17 (2)
- RE: Tom - I appreciate your indulgence in responding so thoughtfully to my posts - tailspn 13:25:43 07/19/17 (1)
- Tom - once again, I appreciate all the time you've spent answering my posts - Chris from Lafayette 14:34:43 07/19/17 (0)