equalizer application in software?

equalizer application in software?

[Derrick J Brashear]

I don't suppose anyone's done an equalizer application in software, e.g.
not a controller for a hardware equalizer as in an AWE? Presumably this
would be something between the audio source and the audio device, or a
library which could be used by applications desirous of such
functionality.

(I assume no such application exists)

-D

Re: equalizer application in software?

[Kadinger Andras]

Hello Derrick,

On Sat, 28 Nov 1998, Derrick J Brashear wrote:

> I don't suppose anyone's done an equalizer application in software, e.g.
> not a controller for a hardware equalizer as in an AWE? Presumably this
> would be something between the audio source and the audio device, or a
> library which could be used by applications desirous of such
> functionality.
> 
> (I assume no such application exists)

I think there might be some audio multiplexing libraries (that takes
audio output of different apps and mixes them together into one stream to 
send to the audio hardware); GNOME/Enlightement at least has one, called
esd or esound I think. Since audio multiplexing is a very good feature, so
is an equalizer, therefore I think building the two together (or at least
making connecting them together simple) is worth the effort.

They also have a wrapper library one can preload to provide this
functionality to 'normal' apps.

Sincerely,
Andras Kadinger
bandit@freeside.elte.hu

Re: equalizer application in software?

[Jason Wilfred Woodford]

On Sat, 28 Nov 1998, Derrick J Brashear wrote:

> I don't suppose anyone's done an equalizer application in software, e.g.
> not a controller for a hardware equalizer as in an AWE? Presumably this
> would be something between the audio source and the audio device, or a
> library which could be used by applications desirous of such
> functionality.
> 
> (I assume no such application exists)
> 
> -D
> 
> 
> 

Hummm..... lemme think.

I know there is a program available somewhere to do a FFT (Fast Fourier
Transform) on a live real-time audio input. Perhaps if you take the
frequency spectrum from the FFT ( it looks like a really high definition
equalizer spectrum...... cool to watch), increase or decrease the
intensity of the frequency components according to your equalizer's band
settings, then recombine the components (a sort of reverse FFT), then you
get the original waveform, except it has been equalized.

What do we think??

Sounds like project..... Where is the prog. to do the FFT? On sunsite?

Feedback appreciated.


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Jason Woodford                  Faculty of Education
Home: 579-2079 Office: 749-7503	Memorial University of Newfoundland
jwoodfd@kelvin.physics.mun.ca	St. John's, NF, CANADA
====================================

Re: equalizer application in software?

[Derrick J Brashear]

On Sun, 29 Nov 1998, Kadinger Andras wrote:

> I think there might be some audio multiplexing libraries (that takes
> audio output of different apps and mixes them together into one stream to 
> send to the audio hardware); GNOME/Enlightement at least has one, called
> esd or esound I think. Since audio multiplexing is a very good feature, so
> is an equalizer, therefore I think building the two together (or at least
> making connecting them together simple) is worth the effort.

esound. 0.2.4 is the most current on ftp.enlightenment.org.

To be honest the architecture used by NAS and to a greater extent by AF
are more appealing to me, namely, be as much like X11 as possible.
However, I do agree that an "audio wrapper" API like esound,AF,NAS, or
maybe even rplay (but probably not) would be a good and logical companion
for such an application.

In order for it to really be useful to me, I need to finish the next stage
of the Linux/Sparc audio midlevel, namely, non-fixed-size,
non-fixed-number buffers.

-D

Re: equalizer application in software?

[Eric B. Mitchell]

Derrick J Brashear wrote:
> 
> On Sun, 29 Nov 1998, Kadinger Andras wrote:
> 
> > I think there might be some audio multiplexing libraries (that takes
> > audio output of different apps and mixes them together into one stream to
> > send to the audio hardware); GNOME/Enlightement at least has one, called
> > esd or esound I think. Since audio multiplexing is a very good feature, so
> > is an equalizer, therefore I think building the two together (or at least
> > making connecting them together simple) is worth the effort.
> 
> esound. 0.2.4 is the most current on ftp.enlightenment.org.

The most recent "stable" release is 0.2.6, cvs snapshots are available 
from e.themes.org, or other gnome cvs sites.  With version 0.2.6, there
is a capability to connect a "filter" socket to the sound server.  A 
sample filter which simply copies data unchanged is included with the
source, so you can see how to interface with it.  

Basically, the server sends the mixed audio data to the filter.  The
filter process reads the information, processes it, and sends it back to 
the server.  The server writes the filtered data to the audio device.

Any decent Digital Signal Processing textbook should have the necessary
algorithms (and maybe even sample code) for implementing a bandpass
filter. The gsl (?) library may be of use for fft and perhaps even 
basic filter functions.

> To be honest the architecture used by NAS and to a greater extent by AF
> are more appealing to me, namely, be as much like X11 as possible.
> However, I do agree that an "audio wrapper" API like esound,AF,NAS, or
> maybe even rplay (but probably not) would be a good and logical companion
> for such an application.
> 
> In order for it to really be useful to me, I need to finish the next stage
> of the Linux/Sparc audio midlevel, namely, non-fixed-size,
> non-fixed-number buffers.
> 
> -D

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| Eric B. Mitchell         mailto:ericmit@ix.netcom.com |
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