IPB

Welcome Guest ( Log In | Register )

Help! Sacd Good Or Bad?, Does SACD ought to sound like crud?
Joe Bloggs
post Sep 9 2002, 12:33
Post #1





Group: Members
Posts: 375
Joined: 29-September 01
Member No.: 55



I've listened to SACD once and it sure sounded good...

I've heard people say that SACD ought to fail in transient reproduction, (because it can only encode a rise and fall relative to the last time step) so I did some calculations:

'Sampling rate' of SACD = 2.8MHz = 64x 44.1kHz

For encoding tones up to 44.1kHz at full scale, it has to reach full-scale from 0 in 64 steps, that is, at any given time there can only be 64 possible positions for the waveform.

This gives it 6 bits resolution to CD's 16 bits??

OK, suppose you only need to encode up to 22.05kHz at full scale, the number of possible positions increases from 64 to 128--7 bits resolution, big improvement blink.gif

I doubt this is how DSD actually works, but this article http://www.iar-80.com/page40.html (I linked to page 40, but it seems page 1-39 may be going on and on about the sonic flaws of DSD as well) seems to take this view seriously and goes on to talk about how you try to recover musical information from the 6 bit stream. blink.gif
Go to the top of the page
+Quote Post
 
Start new topic
Replies
Jasper
post Sep 9 2002, 16:29
Post #2





Group: Members
Posts: 189
Joined: 9-July 02
Member No.: 2536



The general idea is correct, but SACD quality does NOT resemble the quality of 6 or 7 bits PCM (although it would also be incorrect to say it resembles 64bit PCM).
DSD works by determining for each sampling moment wether the sum of the previous errors is above or below a certain level and encodes that in a 1 or a 0 (at least that's more or less what I understand of it). If one would have a signal in which the signal rises from 0 to full-scale in 1/44100th of a second, then DSD would indeed have a BIG problem with that. Luckily for DSD most music doesn't do that, in fact for most music it would be enough (only just, mind you) to encode the difference between this sample and the previous one in 8 bits (assuming 44100Hz and 16bps).
All in all DSD probably sounds better than PCM (at 44100Hz with 16bps), but it does need a lot of noise-shaping and other tricks to work well (to mask all the little errors incurred by the relatively coarse resolution of the steps), which is one of the reasons why I personally don't like the system. But then again I have never really listened to a SACD.

Also keep in mind that the stepsize for DSD could be different than for 16bps PCM, so also because of that it isn't really possible to compare 1bit in DSD with 1bit in 16bps PCM.

Oh, and for those thinking about the very high sampling-rate of DSD and thus assuming it encodes signals upto 1.4MHz, sorry, but it doesn't, in practice the signal is limited to 50 or 100 Khz (because of some necessary filtering, among other things).

BTW, DSD uses delta-sigma modulation and not delta modulation, delta modulation simply looks at the difference between the current value and the previous one, while delta-sigma modulation looks at the sum of the differences and tries to make that as small as possible.
Go to the top of the page
+Quote Post

Posts in this topic
- Joe Bloggs   Help! Sacd Good Or Bad?   Sep 9 2002, 12:33
- - Joe Bloggs   Ok, um, does DSD assume delta modulation or delta-...   Sep 9 2002, 13:33
- - Peter   well, some people are apparently having problems w...   Sep 9 2002, 13:50
- - Joe Bloggs   Problem is, the bits are not employed in the same ...   Sep 9 2002, 14:15
- - Joe Bloggs   This is an example of Sigma-Delta, or Pulse Densit...   Sep 9 2002, 15:16
- - Jasper   The general idea is correct, but SACD quality does...   Sep 9 2002, 16:29
- - Joe Bloggs   So the encoding system is really just plain delta ...   Sep 9 2002, 16:39
- - Jasper   Sorry to have confused you, I didn't have a go...   Sep 9 2002, 16:54
- - 2Bdecided   IIRC, the difference between delta and sigma-delta...   Sep 9 2002, 17:49
- - n68   yup... call it what you wan`t... (i assume...   Sep 9 2002, 18:24
- - mcg1969   I don't think you can fairly say that SACD is ...   Sep 9 2002, 23:42
- - Frank Klemm   QUOTE (2Bdecided @ Sep 9 2002 - 06:49 PM)IIRC...   Sep 10 2002, 01:25
- - crazyboy_T   > - Very critical signal needs time resolution ...   Sep 10 2002, 04:22
- - n68   QUOTE (mcg1969 @ Sep 9 2002 - 10:42 PM)I don...   Sep 10 2002, 10:44
- - Pio2001   QUOTE (crazyboy_T @ Sep 10 2002 - 06:22 AM)Is...   Sep 10 2002, 11:47
- - Frank Klemm   QUOTE (crazyboy_T @ Sep 10 2002 - 05:22 AM)...   Sep 10 2002, 11:57
- - 2Bdecided   It's possible to detect an interaural time del...   Sep 10 2002, 12:36
- - petracci   QUOTE (2Bdecided @ Sep 9 2002 - 06:49 PM)Howe...   Sep 10 2002, 14:53
- - Joe Bloggs   QUOTE Another point: I have serious doubts about t...   Sep 10 2002, 15:01
- - Joe Bloggs   OT: I'd finally figured out what the correct g...   Sep 10 2002, 15:09
- - KikeG   QUOTE (Joe Bloggs @ Sep 10 2002 - 03:01 PM)I ...   Sep 10 2002, 21:27
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 06:09 AM)OT...   Sep 10 2002, 22:33
- - Kim_C   QUOTE (KikeG @ Sep 10 2002 - 11:27 PM)QUOTE (...   Sep 11 2002, 02:51
- - Artemis3   So in other words, the answer to the thread's ...   Sep 11 2002, 04:19
- - Joe Bloggs   Huh? Plain DVD does 24/96? What's DVD-A for th...   Sep 11 2002, 05:42
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 08:42 PM)Hu...   Sep 11 2002, 05:52
- - Joe Bloggs   Any DVD-A records with DRM?   Sep 11 2002, 06:45
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 09:45 PM)An...   Sep 11 2002, 07:12
- - Joe Bloggs   Oh, I mean, any DVD-As without audible watermarks?   Sep 11 2002, 07:37
- - n68   QUOTE (bryant @ Sep 11 2002 - 06:12 AM)All DV...   Sep 11 2002, 08:08
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 10:37 PM)Oh...   Sep 11 2002, 09:24
- - Pio2001   QUOTE (Kim_C @ Sep 11 2002 - 04:51 AM)Audio N...   Sep 11 2002, 11:46
- - Joe Bloggs   So would you agree with this kind of design? What...   Sep 11 2002, 13:33
- - ChristianHJW   Sorry for stepping is so late .... DVD-A vs. SACD ...   Sep 11 2002, 14:26
- - Frank Klemm   QUOTE (ChristianHJW @ Sep 11 2002 - 03:26 PM)...   Sep 11 2002, 14:54
- - user   DVD-Video: Theoretical PCM possibilities for DV...   Sep 11 2002, 14:55
- - ChristianHJW   QUOTE (Frank Klemm @ Sep 11 2002 - 01:54 PM)I...   Sep 11 2002, 15:11
- - Joe Bloggs   OK, so non-oversampling DACs use analog filtering ...   Sep 11 2002, 15:29
- - ChristianHJW   .. arent most modern DACs using a combination of d...   Sep 11 2002, 15:37
- - Kim_C   QUOTE (Pio2001 @ Sep 11 2002 - 01:46 PM)For w...   Sep 11 2002, 16:43
- - Joe Bloggs   What troubles me is that I don't even know wha...   Sep 11 2002, 16:51
- - Pio2001   QUOTE (Joe Bloggs @ Sep 11 2002 - 05:29 PM)Ca...   Sep 11 2002, 20:12
- - Frank Klemm   QUOTE (Joe Bloggs @ Sep 11 2002 - 06:42 AM)Hu...   Sep 11 2002, 20:49
- - KikeG   About non-oversampling filters, I have to say that...   Sep 12 2002, 00:45
- - Kim_C   QUOTE (KikeG @ Sep 12 2002 - 02:45 AM)About n...   Sep 12 2002, 13:53
- - 2Bdecided   I've heard David Chesky's 6 channel 24/96 ...   Sep 12 2002, 14:33
- - KikeG   In reply to Kim_C: It is true that human ear cann...   Sep 12 2002, 14:49
- - Kim_C   QUOTE (KikeG @ Sep 12 2002 - 04:49 PM)This do...   Sep 12 2002, 15:20
- - Kim_C   QUOTE (2Bdecided @ Sep 12 2002 - 04:33 PM)P.S...   Sep 12 2002, 15:52
- - Joe Bloggs   QUOTE (2Bdecided @ Sep 12 2002 - 09:33 PM)P.S...   Sep 12 2002, 16:20
- - KikeG   QUOTE (Kim_C @ Sep 12 2002 - 03:52 PM)"b...   Sep 12 2002, 16:51
- - ChristianHJW   QUOTE (KikeG @ Sep 12 2002 - 01:49 PM)In repl...   Sep 16 2002, 12:41
- - Joe Bloggs   I would also think that you're most likely to ...   Sep 16 2002, 13:03
- - KikeG   QUOTE (ChristianHJW @ Sep 16 2002 - 12:41 PM)...   Sep 16 2002, 18:56
- - Pio2001   QUOTE (ChristianHJW @ Sep 16 2002 - 02:41 PM)...   Sep 16 2002, 23:25
- - ChristianHJW   it was an analog filter i had done using a few op-...   Sep 17 2002, 10:39
- - fewtch   Sheesh... all of this started from an original que...   Sep 17 2002, 10:49
- - Pio2001   QUOTE (ChristianHJW @ Sep 17 2002 - 12:39 PM)...   Sep 17 2002, 11:32
- - fewtch   bleep   Sep 17 2002, 12:12
- - KikeG   QUOTE (ChristianHJW @ Sep 17 2002 - 10:39 AM)...   Sep 17 2002, 12:32
- - ChristianHJW   QUOTE (KikeG @ Sep 17 2002 - 11:32 AM)In the ...   Sep 17 2002, 13:31
- - Joe Bloggs   He said analog filter. The most likely explanation...   Sep 17 2002, 16:01
- - KikeG   QUOTE (ChristianHJW @ Sep 17 2002 - 01:31 PM)...   Sep 17 2002, 17:17
- - Pio2001   QUOTE (KikeG @ Sep 17 2002 - 02:32 PM)You can...   Sep 17 2002, 22:40
- - ChristianHJW   QUOTE (KikeG @ Sep 17 2002 - 04:17 PM)It is a...   Sep 19 2002, 13:56
- - KikeG   Well, I was just intending to explain that this ...   Sep 19 2002, 22:18
- - DickD   Regarding the airy sensation, I concur with KikeG....   Feb 11 2003, 14:41
- - robUx4   QUOTE (KikeG @ Sep 19 2002 - 10:18 PM)About f...   Mar 3 2003, 15:00
- - ChristianHJW   QUOTE (robUx4 @ Mar 3 2003 - 02:00 PM)We basi...   Mar 3 2003, 15:35
- - 2Bdecided   Most of the ideas that are being kicked around her...   Mar 3 2003, 16:02
- - user   http://www.hfm-detmold.de/texts/de/hfm/eti...ten/s...   Mar 3 2003, 16:04
- - ChristianHJW   QUOTE (user @ Mar 3 2003 - 03:04 PM)So, they ...   Mar 3 2003, 16:28
- - Frank Klemm   QUOTE (2Bdecided @ Mar 3 2003 - 05:02 PM)Most...   Mar 3 2003, 19:25
- - robUx4   That would be a very interresting stuff. How many ...   Mar 4 2003, 00:09
- - Pio2001   I've got a 24/96 soundcard, and HD 600 Headpho...   Mar 4 2003, 01:06
- - KikeG   I agree pretty much with Pio's explanations an...   Mar 4 2003, 09:46
- - KikeG   QUOTE (robUx4 @ Mar 3 2003 - 03:00 PM)... but...   Mar 4 2003, 09:50
- - Canar   This is completely off-topic, but I just wanted to...   Mar 4 2003, 10:15
- - robUx4   I just wanted to add something to my paleonthologi...   Mar 4 2003, 10:41
- - Pio2001   QUOTE (robUx4 @ Mar 3 2003 - 05:00 PM)The hum...   Mar 4 2003, 12:29
|- - user   interesting study and paper about difference betwe...   Mar 24 2006, 15:26
- - Pio2001   I remember having read this. It must have been dis...   Mar 24 2006, 16:27
- - SebastianG   I wonder why they have chosen 176,4 kHz at 24 bits...   Mar 24 2006, 16:58
- - Pio2001   Probably to stay close to real-world applications.   Mar 24 2006, 17:36


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 24th July 2014 - 22:16