Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Super Bit Mapping (SBM), can anyone explain? (Read 31320 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Super Bit Mapping (SBM), can anyone explain?

Can anyone explain to me what this process is all about? I have found some technical papers, but since I am an electronic engineer, the digital stuph is not that clear to me.

Another question that bothers me is if the SBM process is the best a man can get, performance-wise. What are the drawbacks? Maybe there is a better way to perform the conversion imposed by SBM?

Regards,
Jacco
Logical reasoning brings you from a to b, imagination brings you everywhere.

Super Bit Mapping (SBM), can anyone explain?

Reply #1 –
A large proportion of today's recordings are made with 24 bit converters. They must be resampled to 16 bit for CD. Some form of dithering and noise shaping is pretty much universally used. This provides some benefit to the very lowest level parts of the recording, allowing people to hear faint audio, such as very quiet orchestral passages or the fade outs applied to many songs, more clearly. The faint audio can be distinguished more readily from background noise and tends to sound 'better.' Also these may be applied to audio recorded originaly at 16 bit for the same reason.

SBM is just one of very many formulas about how to apply dithering/noise shaping. Most people, most of the time, will not notice any difference between different schemes but careful A/B testing may reveal that there sometimes is a difference.

The topic of just what dithering and noise shaping are is fairly large. I'm sure you can find many already written articles and discussions on the web and in any book purporting to cover digital audio.

Super Bit Mapping (SBM), can anyone explain?

Reply #2 –
Thank you AndyH-ha,

As a matter of fact, I am quite familiar with dither and I know how important it is in digital audio. What I do not know are the limitations by SBM. And more important, what are the artifacts of such a process. I just would like to know.

Regards,
Jacco
Logical reasoning brings you from a to b, imagination brings you everywhere.

Super Bit Mapping (SBM), can anyone explain?

Reply #3 –
I understand the basic idea about intellectual curiosity. I don't know if this one can be satisfied vis a vis SBM without buying some Sony recording device that applies it.  SBM may well be a Sony only noise shaping scheme that one cannot get access to elsewhere. Maybe Sony has published a white paper but I tend to think that, if so, it will mainly be hype, that anything and everything important is only in the listening. It can't be basically different than other dither/noise shaping, it will only be a matter of degree, and the success of that degree will most likely be largely a matter of taste.

I only work with CoolEdit/Audition so I don't know the facilities of other audio editors. In Audition it is easy to apply different dither amounts and different noise shaping plans to test if any make a difference to you. You can also create short files of silence and apply to that so the analysis tools can show you the exact results without the confusion of trying to distinguish the dither noise from music.

Super Bit Mapping (SBM), can anyone explain?

Reply #4 –
I think SBM refers to the process of downsampling, dithering & noise-shaping of a DSD signal to a PCM signal (lower sampling rate, higher bit/sample ratio) in one step (in contrast to multi stage decimators) usind a special powerful DSP processor (called SBM processor) that uses a 64k tap FIR lowpass filter -- at least that's what I remember from one of those SACD websites (tech section).

(single stage decimation = keeping requantization effects minimal, requires quite a bit of CPU power)


Sebi

Super Bit Mapping (SBM), can anyone explain?

Reply #5 –
Hasn't SBM been around since the early 90s? That would seem to make it precede DSD.

Super Bit Mapping (SBM), can anyone explain?

Reply #6 –
Perhasp this conversion from DSD is simply using the SBM dither/noise shaping formula as its last step.

Super Bit Mapping (SBM), can anyone explain?

Reply #7 –
Quote
I think SBM refers to the process of downsampling, dithering & noise-shaping of a DSD signal to a PCM signal (lower sampling rate, higher bit/sample ratio) in one step (in contrast to multi stage decimators) usind a special powerful DSP processor (called SBM processor) that uses a 64k tap FIR lowpass filter -- at least that's what I remember from one of those SACD websites (tech section).
(single stage decimation = keeping requantization effects minimal, requires quite a bit of CPU power)
Sebi
[a href="index.php?act=findpost&pid=332212"][{POST_SNAPBACK}][/a]


What you're describing here is "SBM Direct" which is Sony's process for DSD masters.  SBM is the PCM source equivalent.

Super Bit Mapping (SBM), can anyone explain?

Reply #8 –
Quote
Hasn't SBM been around since the early 90s? That would seem to make it precede DSD.
[a href="index.php?act=findpost&pid=332213"][{POST_SNAPBACK}][/a]



Yes.  Sony's SBM CDs began appearing years before SACD.  Other labels had variants on the process (e.g. Deutsche Grammaphon's '4D Sound')

Super Bit Mapping (SBM), can anyone explain?

Reply #9 –
Quote
Yes.  Sony's SBM CDs began appearing years before SACD.  Other labels had variants on the process (e.g. Deutsche Grammaphon's '4D Sound')
[a href="index.php?act=findpost&pid=333432"][{POST_SNAPBACK}][/a]


IIRC 4D is about having a completely digital recording system, with A>D converters in the microphones meaning that all connections, mixing, processing etc in the digital domain.

Removing miles of low voltage microphone cabling carrying delicate analogue signals is supposed to improve the sound quality.

In reality, I suspect it has various plus and minus points.

Also IIRC SBM is just Sony's marketing speak for noise shaped dither. There's nothing really special about it, but its a good idea of course.

Cheers,
David.

Super Bit Mapping (SBM), can anyone explain?

Reply #10 –
Quote from: 2Bdecided on
Quote
Yes.  Sony's SBM CDs began appearing years before SACD.  Other labels had variants on the process (e.g. Deutsche Grammaphon's '4D Sound')
[{POST_SNAPBACK}][/a]


...
Also IIRC SBM is just Sony's marketing speak for noise shaped dither. There's nothing really special about it, but its a good idea of course.

Cheers,
David.


"This process, named Super Bit Mapping Direct, allows to filter and noise shape the DSD signal in a single stage. As a result, interstage requantizing errors are here again suppressed, ripple is eliminated, and aliasing is minimised. This technology has been entirely integrated in a one-stage FIR digital filter / noise shaper, developed by Sony. The resulting 16-bit/44.1kHz signal is finally recorded on the upper layer of the hybrid disc which consequently fulfils the Red Book specifications for Compact Disc and can be played in any existing CD player." [a href="http://www.daisy-laser.com/technology/techsacd/techsacd13.htm]http://www.daisy-laser.com/technology/tech.../techsacd13.htm[/url]
Quis custodiet ipsos custodes?

Super Bit Mapping (SBM), can anyone explain?

Reply #11 –
As somebody already said, it's "YANS" i.e. "yet another noise shaper".
-----
J. D. (jj) Johnston