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DSD-2-PCM -- proof of concept, test sample and source code here
SebastianG
post Oct 8 2005, 23:55
Post #1





Group: Developer
Posts: 1318
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From: Göttingen (DE)
Member No.: 12875



The ZIP contains 4 files:
- dsd2pcm.jar (the converter written in Java, outputs raw 24/88 PCM, intel byte order)
- info.txt (contains some infos)
- test2822k.dsd (14 seconds, mono DSD, 5 megs)
- test44k.mp3 (conversion result)

have fun,
Sebi

Edit-2011: For the latest C/C++ source code see https://code.google.com/p/dsd2pcm/ It is released under the new BSD license. The attatchment to this post is still the first Java release.



This post has been edited by SebastianG: Dec 4 2011, 17:45
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Attached File  dsd2pcm.zip ( 3.56MB ) Number of downloads: 2898
 
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vincefalks
post Dec 7 2009, 17:55
Post #2





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Ok finally my warning was lifted after a little situation was addressed wink.gif .....


Thanks for your information (2Bdecided and rpp3po). Very much appreciated. That's what I'm here for, I got a lot to learn, and I appreciate you sharing your knowledge, which should never be discouraged here (within reasonableness ofc - if it's something that's been discussed to death it would be annoying). Someone like me should not be scared to ask questions in general (and usually it's ones based on uncommon topics like DXD which have certainly not been discussed hardly at all before) and I don't feel that way anyway.

QUOTE (2Bdecided @ Nov 27 2009, 10:59) *
The problem is, unless you've found better sources than me, these sources are just marketing.

e.g. these are sources that also show SACD pulse response being almost infinitely short, while CD is really long (a sinc pulse). This is all-but-nonsense because to get that pulse response from SACD, you have to remove the output filter. If you remove the output filter, you have full scale digital noise - any pulse in there is invisible*. Run this unfiltered signal through an amp and speakers and they'll blow up.

* - so how did they generate these graphs? I can think of three possibilities:

1. They simulated DSD sample frequency with a multibit signal and no noise shaping.
2. They averaged millions of "real" 1-bit DSD "pulse" signals in the multi-bit or floating point domain to remove the noise so that you can actually see the pulse.
3. They drew it with a pen.

I'm not getting how the output filter (a low-pass filter in the analog domain) lessens/makes moot the analog-like impulse response of the digital signal feeding it?... And I'm not sure that the pulse response needs to apply to the ultra high frequencies anyway? If you filter out the noise, you still have the narrow pulse response for the audible band, right?

Secondly: Not that it's a substitute for my own thoughts, and not that I'm defending DSD/DXD (trust me, I'm not, but by the same token I'm not on the pcm-ONLY side either, I'm 100% agnostic and investigative), but this reminds me a bit of the AES papers back and forth about DSD like this and this). Scientifically peer-reviewed papers (am I right in saying that? Are these papers not necessarily peer-reviewed by objective scientifically-minded audio engineers?), arguing against each other (if not well then I'd like to remind, not that it's hugely relevant to my main point right now, about these two scientific studies which plainly contradict each other...). I'm not sure this is _just_ a matter of marketing (which yes I acknowledge, and when I see some of it I laugh too), and what the DSD proponents say, vs. the truth. E.g. in the AES paper defending DSD, they have quite an accurate-looking graphs of impulse response. Is this AES article misleading marketing too? It doesn't look like it's hand-drawn to me.

Btw, I'm not saying higher impulse response is important anyway, just that it was there in the first place and that it appears to be higher in DXD as well...

- - - - -

Now to the DXD matter:

Thanks for the info and those spectrograms!

What I wonder, is how much noise 24-bit 352.8kHz "normal" PCM would have (whatever "normal" is), compared to these 2L "DXD" PCM files? And also, would there be a difference in impulse/frequency response?

The question is, is DXD just a marketing term, and there’s no strict guidelines on what can be called DXD, or does DXD actually have a "format specification" (so to speak), governing exactly what sort of anti-aliasing filter it must have (to be a true DXD encoded signal)? This is why I questioned the claim that a 24-bit 352.8kHz output file from DSD2PCM is a "DXD file".

Of interest is also whether the architecture of the ADC in question has an effect on how much noise there will be....Not that these "optimal" ADCs in the pyramix, AX24 etc DAWs produce low-noise 352.8kHz files (lol). But I once read that the higher the sampling rate, or at least when you start to go above 96kHz, some noise/distortion starts to occur - but that there have however been "advances" in high sampling rate ADC architecture whereby this noise is somewhat reduced - eliminating some past criticisms of 192kHz ADCs. And that the AX24 (one of the few DXD-capable ADCs) is one of those ADCs. Is this correct?

So in the end, the question is whether (true) DXD can only be generated from specific alti-alias settings which match that in the architecture of DXD ADCs manufactured by Digial Audio Denmark (afaik they're all made by the same company, just re-branded into the other DAWs).

QUOTE (krabapple @ Nov 29 2009, 03:56) *
Any high-SR PCM allows for more relaxed filtering compared to Redbook.

DSD (1bit/2.82MHz) was initially meant as an archiving format, not a production format. Then some genius decided consumers should be offered DSD in a delivery format (SACDs). But you can't do common production moves -- e.g., mixing, edits-- in DSD. You have to go to PCM. Hence kludges like intermediate conversion to DXD (i.e., 24bit or 32bit/352.8kHz PCM) by Pyramix, or Sadie's 'DSD-Wide' (waggishly called 'PCM Narrow') which is 8bit/2.82Mhz PCM, followed by final (re)conversion to DSD.
Note that all of the SRs are integer multiples of Redbook's 44.1 (1fs). DSD (8fs) itself was designed to be easily transcoded to PCM in the first place.

The final amusing aspect to all this is that Scarlet Book spec recommends that SACD players incorporate some low-pass filtering (either 50 kHz or 100kHz) to lessen the amount of ultrahigh frequency content the downstream gear would have to (perhaps badly) deal with.

Btw, DXD is not 'new', it's been around since at least early 2004. DSD-Wide's been around even longer.

DXD in the end, is not meant as an editing format for DSD recordings, but as an original master recording format...

They like to record DXD for SACD production because it has almost the same impulse response and frequency response to DSD (within the guidelines of what is "good enough" to them - they say the benefits of DXD outweigh the slight inferiority to DSD in the pulse/freq response departments, and that it sounds better anyway...:|).

And when you compare DXD to PCM/DSD, it IS quite new. Especially in terms of exposure, it's very "new". That's what I meant there.
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Posts in this topic
- SebastianG   DSD-2-PCM -- proof of concept   Oct 8 2005, 23:55
- - skamp   Now you need to develop a DVD-ROM driver for readi...   Oct 9 2005, 01:27
|- - SebastianG   QUOTE (skamp @ Oct 9 2005, 01:27 AM)Now you n...   Oct 9 2005, 10:32
|- - SebastianG   Oh, I noticed a small bug: The dsd file size must ...   Oct 9 2005, 11:06
- - tarsier   So is it theoretically possible to convert the PCM...   Dec 24 2006, 20:33
|- - putanik   QUOTE (tarsier @ Dec 24 2006, 13:33) So i...   Dec 24 2006, 22:54
|- - tarsier   Thanks for the link. But right now, I'm only ...   Dec 26 2006, 16:28
|- - Kees de Visser   QUOTE (tarsier @ Dec 26 2006, 16:28) In d...   Dec 26 2006, 19:03
- - andyshedd   I'm mildly curious how this method compares an...   Jan 8 2007, 22:44
- - frenchglen   Is there any updated info about this program? I tr...   Jun 8 2009, 15:23
- - LukeS   I am bringing this back form years of being dead. ...   Nov 23 2009, 15:56
- - GeSomeone   I think it's in the first post. QUOTE (Sebasti...   Nov 23 2009, 19:12
|- - SebastianG   QUOTE (GeSomeone @ Nov 23 2009, 19:12) I ...   Nov 23 2009, 20:31
- - LukeS   SebastianG, Awesome job on the program, my proble...   Nov 23 2009, 22:32
|- - vincefalks   I am not an expert but it would be cool to compare...   Nov 24 2009, 00:17
|- - rpp3po   What would be a higher quality approach than 1. co...   Nov 24 2009, 02:48
- - SebastianG   QUOTE (LukeS @ Nov 23 2009, 22:32) The ou...   Nov 24 2009, 10:38
- - 2Bdecided   With the huge caveat that I made no attempt to do ...   Nov 24 2009, 12:40
- - vincefalks   The noise is indeed a problem with the DSD format ...   Nov 24 2009, 13:07
|- - rpp3po   The problem with the "most accurate capture...   Nov 24 2009, 14:01
|- - vincefalks   QUOTE (rpp3po @ Nov 24 2009, 15:01) The p...   Nov 24 2009, 14:25
||- - Canar   QUOTE (vincefalks @ Nov 24 2009, 08:25) I...   Nov 24 2009, 15:49
||- - rpp3po   Raw DSD means saving about 3 GB per 70 minute ster...   Nov 24 2009, 17:23
||- - BOBCHEWIE   QUOTE (rpp3po @ Nov 24 2009, 10:23) Raw D...   Jan 3 2010, 12:14
||- - rpp3po   QUOTE (BOBCHEWIE @ Jan 3 2010, 12:14) scr...   Jan 3 2010, 14:15
||- - Axon   QUOTE (BOBCHEWIE @ Jan 3 2010, 05:14) QUO...   Jan 3 2010, 14:22
||- - Martel   QUOTE (BOBCHEWIE @ Jan 3 2010, 12:14) ......   Jan 4 2010, 09:53
|- - Mike Giacomelli   QUOTE (rpp3po @ Nov 24 2009, 08:01) DSD h...   Nov 24 2009, 15:46
- - LukeS   QUOTE (rpp3po @ Nov 24 2009, 08:01) The p...   Nov 24 2009, 21:39
|- - rpp3po   QUOTE (LukeS @ Nov 24 2009, 21:39) 48kHz ...   Nov 25 2009, 03:00
||- - LukeS   QUOTE (rpp3po @ Nov 24 2009, 21:00) QUOTE...   Nov 25 2009, 04:20
||- - Mike Giacomelli   QUOTE (LukeS @ Nov 24 2009, 22:20) QUOTE ...   Nov 25 2009, 05:25
||- - LukeS   QUOTE (Mike Giacomelli @ Nov 24 2009, 23...   Nov 25 2009, 05:29
||- - Mike Giacomelli   QUOTE (LukeS @ Nov 24 2009, 23:29) Also I...   Nov 25 2009, 05:55
|- - vincefalks   QUOTE (LukeS @ Nov 24 2009, 22:39) I am v...   Nov 25 2009, 08:02
|- - knutinh   QUOTE (LukeS @ Nov 24 2009, 21:39) Also t...   Nov 25 2009, 08:36
- - Axon   Look into the dynamic range of SACD at 22khz somet...   Nov 24 2009, 21:56
- - Axon   Yes, let's all thank LukeS for being a boy sco...   Nov 25 2009, 04:59
|- - LukeS   QUOTE (Axon @ Nov 24 2009, 22:59) Yes, le...   Nov 25 2009, 05:21
||- - Martel   QUOTE (LukeS @ Nov 25 2009, 05:21) The bo...   Nov 25 2009, 10:24
|- - 2Bdecided   QUOTE (Axon @ Nov 25 2009, 03:59) Sorry f...   Nov 25 2009, 12:13
|- - udauda   QUOTE (Axon @ Nov 24 2009, 19:59) You...   Nov 26 2009, 02:31
|- - 2Bdecided   QUOTE (udauda @ Nov 26 2009, 01:31) Does ...   Nov 26 2009, 11:46
|- - vincefalks   QUOTE (2Bdecided @ Nov 26 2009, 12:46) Li...   Nov 26 2009, 12:02
|- - rpp3po   Yawn! Am I really the last one to get where t...   Nov 26 2009, 12:37
|- - vincefalks   QUOTE (rpp3po @ Nov 26 2009, 13:37) Yawn...   Nov 26 2009, 13:10
|- - rpp3po   At least you seem believe the life-like-analog-sou...   Nov 26 2009, 13:25
|- - vincefalks   QUOTE (rpp3po @ Nov 26 2009, 14:25) At le...   Nov 26 2009, 13:40
- - LukeS   QUOTE (vincefalks @ Nov 25 2009, 02:02) Q...   Nov 25 2009, 09:16
|- - SebastianG   QUOTE (LukeS @ Nov 25 2009, 09:16) See th...   Nov 25 2009, 10:32
|- - knutinh   QUOTE (LukeS @ Nov 25 2009, 09:16) DST wo...   Nov 25 2009, 18:02
|- - simmconn   QUOTE DST would work but I have not found a no low...   Nov 26 2009, 01:31
|- - vincefalks   QUOTE (simmconn @ Nov 26 2009, 02:31) QUO...   Nov 26 2009, 03:38
- - rpp3po   Sorry, if I didn't express myself clearly enou...   Nov 25 2009, 12:04
- - Axon   It's a surprisingly well known mod, actually. ...   Nov 25 2009, 19:38
|- - rpp3po   I find it interesting, nevertheless. What equipmen...   Nov 25 2009, 20:38
- - LukeS   Wow, I really am messing thing up lately ; I got ...   Nov 26 2009, 07:27
|- - simmconn   And I just spent one and a half hours to encode an...   Nov 26 2009, 08:16
- - 2Bdecided   Yes, the distortions of SACD are inaudible. Especi...   Nov 26 2009, 15:57
- - Canar   So that's what they mean by "warm" s...   Nov 26 2009, 16:22
- - Axon   If SACD really did have a similar distortion profi...   Nov 26 2009, 21:14
- - SebastianG   Just for kicks and giggles I rewrote most of ...   Nov 27 2009, 03:26
|- - vincefalks   QUOTE (SebastianG @ Nov 27 2009, 03:26) J...   Nov 27 2009, 03:44
|- - SebastianG   QUOTE (vincefalks @ Nov 27 2009, 03:44) T...   Nov 27 2009, 04:14
||- - vincefalks   QUOTE (SebastianG @ Nov 27 2009, 04:14) S...   Nov 27 2009, 05:11
||- - Kees de Visser   There seems to be a growing (niche) market for onl...   Nov 27 2009, 09:02
||- - 2Bdecided   QUOTE (vincefalks @ Nov 27 2009, 04:11) N...   Nov 27 2009, 10:59
||- - rpp3po   QUOTE (vincefalks @ Nov 27 2009, 05:11) N...   Nov 27 2009, 12:55
|||- - 2Bdecided   QUOTE (rpp3po @ Nov 27 2009, 11:55) An an...   Nov 27 2009, 13:00
||- - krabapple   QUOTE (vincefalks @ Nov 26 2009, 23:11) T...   Nov 29 2009, 03:56
|- - rpp3po   QUOTE (vincefalks @ Nov 27 2009, 03:44) H...   Nov 27 2009, 04:16
- - LukeS   QUOTE (SebastianG @ Nov 26 2009, 21:26) J...   Nov 27 2009, 07:33
|- - smack   QUOTE (LukeS @ Nov 27 2009, 07:33) Window...   Nov 27 2009, 11:00
- - .halverhahn   DXD is PCM - just with a bunch of noise above 48kH...   Nov 27 2009, 15:34
|- - rpp3po   Wow! The DXD track is certainly nothing Bruce ...   Nov 27 2009, 17:47
- - spoon   As the noise is constant this shows the levels qui...   Nov 29 2009, 20:54
- - spoon   QUOTE The final amusing aspect to all this is that...   Nov 29 2009, 22:51
|- - krabapple   QUOTE (spoon @ Nov 29 2009, 16:51) QUOTE ...   Nov 30 2009, 06:33
- - spoon   Based on Sebastians good work I have wrapped the d...   Dec 1 2009, 17:49
- - kode54   @spoon: I presume you modified the stage 1 filter ...   Dec 1 2009, 19:55
- - spoon   I thought it was a command line option on dsd2pcm?   Dec 1 2009, 20:15
|- - kode54   QUOTE (spoon @ Dec 1 2009, 11:15) I thoug...   Dec 7 2009, 15:32
- - krabapple   This is all peachy for those recording DSD files o...   Dec 2 2009, 06:56
|- - BOBCHEWIE   QUOTE (krabapple @ Dec 1 2009, 23:56) Thi...   Jan 3 2010, 13:33
- - spoon   I might be wrong, but I do not think there are any...   Dec 2 2009, 09:55
|- - krabapple   QUOTE (spoon @ Dec 2 2009, 03:55) I might...   Dec 2 2009, 17:23
- - Martel   QUOTE There are three types of SACDs[9]: * Hy...   Dec 2 2009, 10:35
- - .halverhahn   Just for your information: Wheatus is offering The...   Dec 2 2009, 11:38
|- - 2Bdecided   QUOTE (.halverhahn @ Dec 2 2009, 10:38) J...   Dec 2 2009, 15:11
- - vincefalks   Ok finally my warning was lifted after a little si...   Dec 7 2009, 17:55
|- - krabapple   QUOTE (vincefalks @ Dec 7 2009, 11:55) QU...   Dec 7 2009, 18:26
|- - 2Bdecided   QUOTE (vincefalks @ Dec 7 2009, 16:55) I...   Dec 7 2009, 18:33
|- - spoon   Did anyone manage to decode a .dsf file? (such as ...   Dec 8 2009, 10:21
- - Martel   A (square analog) pulse has an infinitely wide spe...   Dec 7 2009, 18:26
- - udauda   I wonder, how come Pro-DSD never comes up with a s...   Jan 4 2010, 13:39
- - rpp3po   Excellent paper, thanks!   Jan 4 2010, 14:31
- - krabapple   I remember this one from a few years back....I for...   Jan 8 2010, 22:05
- - ElfeJoyeux   Hello, I just discovered this awesome topic durin...   Mar 11 2010, 22:34
|- - Hobbit13   QUOTE (ElfeJoyeux @ Mar 11 2010, 22:34) T...   Jul 19 2010, 10:48
- - Sik_Lescinovid   Has anyone so far noticed that when creating a 24 ...   Nov 27 2011, 18:28
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