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16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain



 
 
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  #61  
Old November 18th 03, 01:56 PM
Arny Krueger
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

"S O'Neill" > wrote in message

> Arny Krueger wrote:
>
>> A DSD data stream is composed of pulses that are basically
>> integrated to produce an analog signal. Pulses have a value of
>> either +1 or -1. Alternate pulses with opposite polarities sum out
>> to zero. If the pulses are predominately +1, then the integrated
>> signal goes positive. The more predominately the pulses are +1, the
>> faster the integrated signal goes positive. If the pulses are
>> predominately -1 then the integrated signal goes minus, and so on.

>
> Didn't that used to be called 1-bit DPCM?


Here are block diagrams of a DPCM coder and decoder

http://ce.sharif.edu/~m_amiri/Projects/MWIPC/dpcm1.htm

On page 7 of

http://www.hit.bme.hu/people/papay/edu/Acrobat/DSD.pdf

there is a block diagram of a DSD decoder.

Don't look the same to me.


Ads
  #62  
Old November 18th 03, 02:27 PM
Justin Ulysses Morse
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

Garthrr > wrote:

> Following this analogy -- and I just know I'm gonna be wrong here but this is
> just how it seems to me -- if we say, for example, that 16 bit audio is like
> having a pocket full of 10 dimes then isnt 24 bit audio a pocket full of 100
> pennies? Finer divisions of the same whole--the ability to describe finer
> voltage differences?


Yes. For the sake of discussion, let's say you have a thousand dollars
in either dimes or pennies.
Now, say you're going to make a single purchase of something that costs
$1.87. At 16 bits, you're forced to tell the clerk to "keep the
change" because all you have are dimes. No big deal, you're out $0.03.
You'll never miss it. Most of us wouldn't bother stooping to pick up
three pennies. But suppose you're going around town buying a whole
bunch of different things, and every time you do, you have to say,
"keep the change." Eventually, it starts to add up and you wish you
had some pennies.

Suppose you record live to 2-track at 16 bits and you just make a
single "transaction" where you maybe run an EQ, a gain boost, and a
little peak limiting all in one pass. You're using 24-bit DSP but you
have to stuff the result back into a 16-bit package. Not a real big
deal, your "clerk" rings you up and says that'll be $45.58. You only
have to say "keep the change" once.

But now what if you've got a bunch of different processes to run,
incrementally, that you evaluate before you move on to the next
process? Maybe you're multi-tracking and you're processing each track
differently. There's all kinds of "keep the change" adding up. In
fact, it's not only "adding up" but it's also "multiplying up." The
error in your first process will get multiplied in your next step. I
guess that would be something like if you bought 1000 of something that
should cost $0.13 apiece but since you're paying in dimes you're paying
$0.20 apiece. Suddenly you're out $70. Your accountant is gonna be
****ed.

This is why more processing means you should start with more bits. But
you know, decimal places on a calculator is probably a better analogy.
Should I start again?

ulysses


> I understand that the dynamic range increases with higher bit depth and I
> guess
> in this money analogy we could think of that as having a dollar fifty or
> something instead of the original dollar but it still seems like you get finer
> resolution even in the first dollar.
>
> Is this question not analogous to the number of pixels in a digital
> photograph?
> The more pixels, the higher resolution the picture (all else being equal).
> That
> being analogous to bit depth in audio then the rate of frames per second in a
> moving picture would be analogous to sample rate. Is that a reasonable
> comparison?
>
> Sooner or later I'll phrase this question in enough different ways as to
> clearly communicate what I want to ask!
>
> Garth~
>
>
> "I think the fact that music can come up a wire is a miracle."
> Ed Cherney

  #63  
Old November 18th 03, 02:33 PM
Justin Ulysses Morse
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

Garthrr > wrote:

> Actually I was under the impresion that Jay was on the other side of the
> fence--that he was saying that 24 bit was really no better than 16 bit for any
> sort of real world audio. Perhaps I misunderstood his stance. I thought it was
> Arny who was contending that there is resolution to be gained by 24 bit,
> resolution which exists even in the not-so-low level signal.


You've understood Arny correctly but have gotten the wrong idea about
what Jay is trying to say. On his website he advocates going to at
least 20 bits for a release format, or better yet 24 bits. The
perceived disagreement (which turned out not really to be a
disagreement at all, if you ask me) revolved around the *reason* for
needing more bits. Jay seems to think 24 bits is better than 16 bits
because of the extra low-level resolution.

I actually disagree about the need for more bits in the delivery
medium. I think 16 is enough to deliver the full fidelity of any
real-world finished production, even though 24 bits are needed during
tracking, mixdown, and mastering.

ulysses
  #64  
Old November 18th 03, 02:41 PM
Garthrr
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

Ok, considering the post below, then the question is "Where is the disagreement
between the two camps-- the one camp who says 16 bit is as good as 24 bit for
anything but very, very low level audio and the other camp that says 24 bit is
better even at higher recording levels? Where is the point at which the two
camps begin to disagree?

Garth~


In article > , Justin Ulysses
Morse > writes:

>Yes. For the sake of discussion, let's say you have a thousand dollars
>in either dimes or pennies.
>Now, say you're going to make a single purchase of something that costs
>$1.87. At 16 bits, you're forced to tell the clerk to "keep the
>change" because all you have are dimes. No big deal, you're out $0.03.
>You'll never miss it. Most of us wouldn't bother stooping to pick up
>three pennies. But suppose you're going around town buying a whole
>bunch of different things, and every time you do, you have to say,
>"keep the change." Eventually, it starts to add up and you wish you
>had some pennies.
>
>Suppose you record live to 2-track at 16 bits and you just make a
>single "transaction" where you maybe run an EQ, a gain boost, and a
>little peak limiting all in one pass. You're using 24-bit DSP but you
>have to stuff the result back into a 16-bit package. Not a real big
>deal, your "clerk" rings you up and says that'll be $45.58. You only
>have to say "keep the change" once.
>
>But now what if you've got a bunch of different processes to run,
>incrementally, that you evaluate before you move on to the next
>process? Maybe you're multi-tracking and you're processing each track
>differently. There's all kinds of "keep the change" adding up. In
>fact, it's not only "adding up" but it's also "multiplying up." The
>error in your first process will get multiplied in your next step. I
>guess that would be something like if you bought 1000 of something that
>should cost $0.13 apiece but since you're paying in dimes you're paying
>$0.20 apiece. Suddenly you're out $70. Your accountant is gonna be
>****ed.
>
>This is why more processing means you should start with more bits. But
>you know, decimal places on a calculator is probably a better analogy.
>Should I start again?
>
>ulysses
>
>





"I think the fact that music can come up a wire is a miracle."
Ed Cherney
  #65  
Old November 18th 03, 02:51 PM
Garthrr
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

In article > , Justin Ulysses
Morse > writes:

>I actually disagree about the need for more bits in the delivery
>medium. I think 16 is enough to deliver the full fidelity of any
>real-world finished production, even though 24 bits are needed during
>tracking, mixdown, and mastering.


Yeah this is a good point IMO. The reason is that in the real world where
things are sometimes done in a hurry and levels are not always set to optimum,
having that overkill is a good thing. Not to mention the fact that tracks get
EQed and compressed all to hell which of course brings up the noise floor and
exposes low level signals more than they would be otherwise. I can think of a
session I did a week ago where the drummer used brushes on one song very
quietly and I didnt feel like resetting the levels of all ten tracks so I just
left them, knowing that I would be fine with my 24 bit system.

In the delivery medium you can be pretty sure (especially these days with the
"level wars") that the full potential of the medium is going to be exploited.

Garth~


"I think the fact that music can come up a wire is a miracle."
Ed Cherney
  #66  
Old November 18th 03, 03:16 PM
Mike Rivers
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain


In article > writes:

> >24 bits also adds resolution in any region between -144 dB and full scale.

>
> For me, with my limited understanding (or misunderstanding perhaps) of digital
> theory, the above sentence cuts to the heart of the matter. If I understand
> what Scott Dorsey and others have said then the change from 16 to 24 bits only
> adds downward dynamic range and does not increase resolution of signals in the
> relatively high ranges close to full scale.


You really have to know how to interpret this. It's easy to hear low
resolution at low levels - the limiting case is that the level is so
low that the lowest order bit never gets turned on, yet you know
there's something there. That's insufficient resolution. Go up just a
tad higher in level so that the lowest bit toggles once each cycle
(assuming a constant amplitude sine wave going in) and your sine wave
gets turned into a square wave. However, in a practical system, you'd
have to amplify by 90 dB or so in order to hear it at normal listening
volume, and we don't do that other than to show why 20 bits is better
than 16.

What having more bits allows you to do is trade off some resolution
at the top end that you won't ever hear anyway in favor of additional
working headroom. You can better deal with music with a wide dynamic
range if you have 20 dB between your nominal recording level and
maximum level than if you have only 10 or 6 dB. This is the practical
advantage to working with more bits.



--
I'm really Mike Rivers - )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo
  #67  
Old November 18th 03, 05:30 PM
[email protected]
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

Justin Ulysses Morse > wrote:
|
|While it's true that the additional bits tack your extended resolution
|onto "the bottom" of the dynamic range, it clearly increases the
|resolution at all levels. You can have a -100dB component to a -1dB
|signal, and you still want to hear it.

Is the ear even capable of hearing the -100 component against the much
louder -1? I thought masking pervented this.

Phil
  #68  
Old November 18th 03, 05:47 PM
Tommi
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain


"Justin Ulysses Morse" > wrote in message
m...
> Thanks for this explanation, Arny. Idunno if it helped Tommi but it
> helped me. Every time I finally grasp another "big concept" in digital
> audio I'm always amazed at how incredibly clever it is. Those old
> French mathmen must have been giddy as hell when they figured this
> stuff out.
>
> ulysses
>



Yes, it was indeed an informative reply from Arny!


  #70  
Old November 18th 03, 06:02 PM
Tommi
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain


> wrote in message
...
> Justin Ulysses Morse > wrote:
> |
> |While it's true that the additional bits tack your extended resolution
> |onto "the bottom" of the dynamic range, it clearly increases the
> |resolution at all levels. You can have a -100dB component to a -1dB
> |signal, and you still want to hear it.
>
> Is the ear even capable of hearing the -100 component against the much
> louder -1? I thought masking pervented this.
>
> Phil


Masking, it is frequency-dependent. However, this leads to thinking about
the fact that the human ear actually compresses dynamics at higher sound
pressures. My understanding is that we have roughly 80dB's worth of dynamic
range at a time, which we then move according to the sound pressure levels
of the sound sources.
For example, if you'd be listening something at 110dB SPL for 5 minutes,
after that you couldn't hear the same sound with 2dB SPL for a while. It
works the other way round too: If you're listening something at 5dB spl for
a while, and then suddenly the same sound source produces a 120dB spl sound,
your ear would compress it lower(by stretching the eardrum, moving the
hammer away from it etc) in order to protect your hearing mechanism. This,
however isn't true with very short peaks because your protection mechanism
takes some time to wake up.


 




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