gamedevlists-general

[GD-General] Sound

[Ken N. <kn...@wh...>]

Hey,

=20

Anybody know any good sound lists or really great articles on software
sound mixing? I built a continuous streaming sound system and I'm having
difficulties mixing two sounds together. Just doing an addition to the
two sound samples produces errors when the sound wraps around the
limitations of a signed short. Clamping that doesn't work either since
sound is measured in a difference of samples. Doing an average on the
two sound samples causes sounds to be more quiet then they should
naturally be, so is there a better way?

=20

Thanks,

-Ken Noland

Re: [GD-General] Sound

[Brian H. <ho...@bo...>]

 On Sun, 15 May 2005 11:42:03 -0400, Ken  Noland wrote:
> Anybody know any good sound lists or really great articles on
> software sound mixing?

Try a good book on sound programming, several of them exist.  Off the 
top of my head is A Programmer's Guide to Sound by Kientzle.

> an addition to the two sound samples produces errors when the sound
> wraps around the limitations of a signed short.

Yes.  Welcome to sound programming =3D)

> Clamping that
> doesn=92t work either since sound is measured in a difference of
> samples.

Clamping doesn't work, period, since you end up clipping and 
introducing distortion as a result.

> Doing an average on the two sound samples causes sounds to
> be more quiet then they should naturally be, so is there a better
> way?

Well, an average is just doing the addition and then rescaling the 
results, which isn't always going to help you and just raises the 
noise floor.

There is no easy way around this.  It's a large, complicated topic, 
but the simplest answer (until you learn about the intricacies 
involved) is "use quieter sounds".  That way when you sum a bunch of 
them, they hopefully won't clip, but even that's not a guarantee.

Some fancier stuff mixes in floats and rescales on the fly, or applies 
real-time compression/limiting, but that starts getting into the realm 
of REAL complicated for someone without sound programming experience.

Brian

Re: [GD-General] Sound

[Thatcher U. <tu...@tu...>]

On May 15, 2005 at 12:55 -0400, Brian Hook wrote:
>  On Sun, 15 May 2005 11:42:03 -0400, Ken  Noland wrote:
> 
> > Clamping that
> > doesn?t work either since sound is measured in a difference of
> > samples.
> 
> Clamping doesn't work, period, since you end up clipping and
> introducing distortion as a result.

In my experience, clamping has worked pretty well.  Much better than
it has a right to.

The main case where it works badly is when you have two (or more) of
the same sound triggered at exactly the time.  If you can avoid that
case, then you may not be able to hear the clipping at all.  YMMV.

-- 
Thatcher Ulrich
http://tulrich.com

Re: [GD-General] Sound

[Brian H. <ho...@bo...>]

> In my experience, clamping has worked pretty well.  Much better
> than it has a right to.

I believe this depends on the degree of clamping.

> The main case where it works badly is when you have two (or more)
> of the same sound triggered at exactly the time.  If you can avoid
> that case, then you may not be able to hear the clipping at all.
> YMMV.

When the same sound is triggered multiple times, it just means the 
amplitude is going through the roof, so the clipping is a far more 
apparent since you get a heavily clipped wave form.

A lightly clipped wave form isn't going nearly as bad, it pretty much 
comes down to how "chopped" the signal looks.  It's still better than 
allowing it to wrap, however, which introduces all kinds of nasty pops 
and clicks.

If you're not clipping often, then I don't think you'll hear it too 
often and it gets absorbed into the noise.

Brian