![]() The shape and timing of the impulse would be completely retained since the 2.8224 MHz sampling rate of DSD64 provides ~29 samples within each 96kHz time period. From a time domain perspective, the SACD conversion process is excellent. Notice again the amount of noise in the signal and again, we see the superiority of DSD128. When I convert this waveform to DSD64 and DSD128 with Saracon and then back to PCM with the foobar SACD plug-in to 24/352 unfiltered (retaining all that ultrasonic noise), you get the 2nd and 3rd left images. Even though Adobe Audition renders the interpolation, the actual PCM data itself is a simple, single "pulse" (see Addendum below for screenshots using Audacity). In the top left panel, this is what a 0dBFS 24/96 "impulse" would look like with a typical linear-phase oversampling interpolation showing symmetrical pre- and post-ringing. Let's see what a 24/96 impulse looks like after going through the DSD encoder and most of the decoders I looked at (DSD-to-PCM converter output set to 24/352 for each, AudioGate's max was 192kHz): The question is, just how much noise reduction should we actually do? (You can also see the noise through an analogue oscilloscope - as shown here.)Īs noted by Juergen in the comments to the previous post, there is this matter about time-domain behaviour as well which can be skewed as we apply various filters. Notice that DSD128 is significantly less noisy. This is what all that extra high-frequency noise looks like in DSD when you don't filter it out at all. If you feel there is no need to retain frequencies >20kHz, then this will clearly get the job done.īut wait, there's more! SACD Plug-in also has a 30kHz lowpass mode - "Direct - (Double Precision, 30kHz LF)". This is done with a very strong low-pass filter. The AuI ConverteR software puts up some impressive numbers. I would not be surprised if the algorithm (DSD2PCM) is essentially the same if we look "under the hood".Ģ. foobar SACD plug-in works about the same as the old DSDIFF plug-in. Otherwise, foobar DSDIFF and the newer SACD plug-ins appear very similar.īasically, this is what we can say at this point.ġ. That little bit of high-frequency "rippling" with DSDIFF is probably a result of the resampling algorithm. That is an impressively sharp, precise filter at 20kHz! I can approximate that effect with iZotope RX 4's EQ plug-in with a low-pass at 20kHz, high Q of 25 or so (not shown) but AuI ConverteR looks even cleaner with less noise floor irregularity.
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