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jack_convolve - a simple commandline convolution engine for jackd

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What is it?

jack_convolve is a convolution engine. It convolves one (or more) signals with one (or more) impulse responses (IR). For this it uses the partitioned convolution technique.

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What is convolution good for?

Well, it can be used, for example, to create good sounding reverbs (listen to Example 5 further down the page), but is not limited to that. Basically any soundfile can be used as a response file.

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How does it perform?

Keep in mind though that the convolution gets more expensive as the length of the response file grows. Here on my Athlon 1.2ghz i can use a ca. 1 sec response file at a cpu load of around 10-15% (at a jack periodsize of 2048 ;)).

Also the cpu usage increases antiproportional to the partition size. Means: if at a jack period size of N jack_convolve uses M% dsp time, then it will use (2*M)% dsp time at a periodsize of N/2.

So if your box comes to a grind, you get millions of xruns and everything is sluggish, this doesn’t mean jack_convolve is broken but rather that you

a) used a too small periodsize

b) used a too long responsefile

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Downloads:

Grab it here
Latest versions are jack_convolve-0.0.13.tgz and libconvolve-0.0.6.tgz

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How to build:

It’s simple. Untar the source tarball, change into the newly created directory and type:

then as root:

The binary will then live in

If you want it in

either change the Makefile or move it there:

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Requirements:

fftw3f

libsndfile

SRC (a.k.a libsamplerate)

libDSP

libconvolve

of course the -dev versions of the respective packages are needed if you use distribution packages..

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Example sounds:

example 1

http://tapas.affenbande.org/jack_conv_ex2.ogg

http://tapas.affenbande.org/jack_conv_ex3.ogg

These ones sound better (although 4 has some room on its own):

http://tapas.affenbande.org/jack_conv_ex4.ogg

http://tapas.affenbande.org/jack_conv_ex5.ogg

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Using the convolution code in your own application:

The convolution code itself is pretty neatly wrapped into the shared library libconvolve. It basically consists of two files:

The former provides a simple 3 call API. The latter implements it. Keep in mind though that it is licensed via GPL. Alternative licenses can be negotiated.

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Where to get response files for cool sounding reverbs?

Have a look at

http://noisevault.com

They have quite a bit of stuff, plus links. Also a google search for “IR reponse files” might show some stuff.

Or simply create your own (you need some serious high quality gear for this though).