Saturday, September 17, 2016

SACD and DSD in DVP-9000ES vs HDCD

I take this mostly as representative as SACD the system, not my particular unit or the DVP-9000ES more specivically.  Because it's how I'm thinking of it all.  I think this unit represents DSD as it was first implemented, with something very much like the 1-bit converters Sony had been using for years, and not the oversampled multibit implementations, which have been the norm ever since the 3rd generation or so.  And it's characteristic of DSD itself, in any implementation, but more purely in its original implementation, where the limitations are more obvious.  So I'm going to say DSD and not "my DVP-9000ES" but you can do the translation back if you don't accept that equivalence.

DSD has a smoothing effect mostly.  That's actually the subjective effect of adding noise above 10kHz, and possibly that's the cause of it.  But it can also open up dynamically, and suddenly get more bite than PCM.

I've recently noticed HDCD has an effect like that, apparently under the producer's control.  The producer can apparently control the sharpness of the digital filter in your system.  Some make it sharp, some make it soft, RR recordings you never notice because they do it frame by frame with the PMI recorder.  I think this is a good idea, to give the producer some control over the playback digital filter, and I like HDCD, perhaps an open standard system would be better than a proprietary one, but HDCD recordings as they exist are generally quite good and advantaged slightly over PCM 44.1/16 as a result.  There actually is a tiny information loss to power the coding system, but it's negligible compared with DSD.  Only a few bits are necessarily stolen by HDCD in full decoding (of course in non-decoding you are possibly getting a compressed form, so that part was not helpful to gaining wide acceptance--the "compatiblity" claim is actually overstated...then again the story in standard CD masterings being all over the map and endless remasterings to endlessly bilk consumers is no pretty picture either...there's really no compatibility in CD's every version is different, and one might be suspicious in hybrid CD/SACD discs that the CD is somewhat dumbed down to make the SACD shine, and in fact if they use 1-bit conversion throughout that would probably be the result).

DSD has this opening up and closing down aspect...but it appears seamlessly as part of the system, apparently driven by the demand for it in the music.  So that's good in some ways, less possibility of error, but I don't think it's much if any better than 44.1/16 PCM and I'd rather have HDCD or High Rez...but perhaps the same actual mastering used in the high rez recordings would work at 44.1/16 too, if they'd just do that.  Mostly the whole "High Rez" thing is to force people who want better masterings to pay more for everything.  It's a bribe to the Engineer not to crank up the compression machine.

I still feel the information loss in SACD (which I admit, is equivalent to the HF noise above 10kHz*, so well you might say, why worry, but there it is, that's what information loss looks like) gives the sound a simplified character generally, like MP3,  only very very slightly, just enough to make things sound better a bit, like blur on a photo.  Generally.

(*And I'm not exactly sure how to count the noise shaping, it hides the information loss within the audible range by creating vastly greater information loss above, but it can't add lost information.  Information loss need be applied to the raw S/N curve, not the noise-shaped one.  Actually, in a wide band, that would probably make it seem better anyway, but my information loss argument applies strictly speaking to the known audible range, and in that case I think it's pretty big.  I'm not exactly sure how to square this with apparent low noise in the midrange in measurements of DSD...but once again I think that's primary the bogus result of noise shaping, without which there would be noticeably more noise in the midrange and upper midrange.  In principle, despite noise shaping I think, DSD adds information up to the actual nyquist frequency, say 1.4Mhz more than equal to it's loss within the audible range, it uses lotsa bits.  But who cares about added information above 100kHz, which is filtered away in the end anyway?  Am I missing something here?)

So I wouldn't recommend DSD, but if a producer has chosen it, it's just another artistic brush, may not kill things for the first few hundred listenings, there's really so much information in music anyway, most of the time we're throwing away almost all of it, only sometimes reaching more than a tiny fraction.

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