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Re: dither

Subject: Re: dither
From: "Rich Peet <>" <>
Date: Thu, 12 Dec 2002 00:52:26 -0000
Yes at this time I don't understand what the typical artifacts sound 
like.  I am trying to understand the default settings ideal for 
Cooledit for making "stuff".

It appears that the recommendations from my readings is to have 
dither "on" with Triangular shapes until the final "master". Then on 
the final mix I can use a different "shape".  It also appears I 
should do everything converted to 32 bit before edits and I should 
spend a whole lot of money on a new computer as this "chunk o junk" 
is limping. I am going gray on this stuff fast.

Rich Peet

 
--- In  Walter Knapp <> 
wrote:
> Rob Danielson wrote:
> > Thank for the comments, Walt.  Please see inserts
> > Rob D.
> 
> >>I'm not inclined to buy in so big to the low end being somehow 
unique in
> >>number of bits actually used. A high intensity sound that has 
little
> >>dynamic range will be just the same. And in most cases we are 
really
> >>talking sounds that are only about half way down in the dynamic 
range,
> >>not stuff way down at the bottom.
> > 
> > 
> > I was thinking of lower levels, say around 2-4% saturation in the 
> > orig field recording-- about the amount I'd quess Rich would be 
> > working with if he's hearing dithering artifacts.
> 
> I'm not sure that's all that likely. Anyway, If I found myself in 
that 
> area I'd be thinking more about getting closer or something, it 
would be 
> hard to even monitor what was going on. As I noted, what I've been 
able 
> to tell we don't normally get down in the lower end of the range of 
our 
> recorders much. Even if it's a 94 dB DAT, that's a lot of dynamic 
range 
> to play with.
> 
> Rich can tell us, but my impression was that he was worrying over 
how to 
> avoid dithering artifacts but did not have any clear cut ones. Or 
more 
> precisely what way to set up his software in light of using better 
mics.
> 
> 
> >>The dynamic filter I use most of the time works on all 
frequencies at
> >>once. It would be nice to have a filter that combined a multi-
band eq
> >>with dynamics. As it is most eq just moves the gain moving the 
whole
> >>range at once. In my case being able to remove, say, loud insects 
at a
> >>certain frequency range while preserving the lower level ambiance 
at
> >>that range is what I'm talking about. Or maybe being able to set 
the
> >>upper and lower limits of the dynamic range for that band that 
will be
> >>passed would be a good way to have it.
> > 
> > 
> > 
> > Perhaps something like Waves C4?  I'm trying to learn how to use 
C4 
> > effectively for this but not with much success.
> 
> I can do it in Spark XL's filter setup by creating multiple 
filtering 
> paths. But it would be pretty complex to set up and quickly very 
> processor intensive. Right now the nicest dynamic range filter I've 
> found in stuff I have is in Soundhack, but it only provides for one 
cut 
> point and does all frequencies. It's nice for cleaning up small 
messes 
> has to be used very carefully or your main sound will suffer. I'm 
> learning a bit about the structure of sound playing with it, and 
have 
> made a little practical use of it.
> 
> When you figure out Waves C4 I'd be interested in a report. I can't 
> afford to buy every piece of software.
> 
> Spark XL has just been upgraded. And there are some new filters to 
find 
> out about. Once my copy arrives. Sounds like they have upgraded 
their 
> active noise filter a fair bit.
> 
> Part of the problem with detailed dynamics filtering is that I 
don't 
> think it is possible except with a computer. The sound world is 
still 
> mostly running on imitations of what used to be hardware and will 
be 
> slow to move into new areas. Got to think outside the comfortable 
old 
> hardware box.
> 
> >>I would certainly agree that much of the noise we deal with is in 
the
> >>lower frequencies, but this is a different issue. Bit depth is 
sound
> >>intensity. A frequency filter will change intensity, but is not
> >>specifically filtering along the intensity line.
> > 
> > 
> > 
> > My guess is a good part of the choppiness that stems from the low 
bit 
> > rate becomes most audible in the low range,.. have no proof of 
this, 
> > just that selective reduction works best in that range.
> 
> I would guess the opposite as higher frequencies have much less in 
the 
> way of samples to define the waveform. At 100 hz you have hundreds 
of 
> samples per cycle. Any error would tend to average out there. Up at 
the 
> high end you may only have a sample or two to define the waveform, 
> that's really going to show any error. It's also what should show 
the 
> greatest degradation from dither too. Selective reduction probably 
works 
> best in the low range because you have so many more samples to work 
with.
> 
> I've always maintained that virtually the upper half of the 
available 
> frequency range in digital is very crude. When that's important the 
best 
> thing you can do is go to higher sampling rates. That's probably 
more 
> important than bit depth in that case. Much of what's thought to be 
bit 
> depth problems would go away with higher sampling rates.
> 
> For me that's not a big problem, 8khz is about the top for the 
frogs I 
> deal with. Though there is at least one frog that goes up into the 
> ultrasonic. I'm also old enough that I don't hear high frequencies 
all 
> that well so am unlikely to take up recording high frequency calls.
> 
> Walt
> 



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