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I've made impulse to correct my speakers response, and would like to use it in my Ubuntu 11.04.

Only possible (in common sense) way seems to be through Jack and jack_convolver plugin. As not all applications communicate with Jack, nor I run it all the time, I would like to know for other possibility if present.


I got 'tumbleweed' badge for this unpopular question, and thought to demystify it with a bounty and little comment :)

First, I know very little about Ubuntu's underlying audio stack, as I'm new to Linux. I think that question is asked clearly for those who might know about it. Then here is what I got so far:

  1. It seems this is possible through module-ladspa-sink with which help I could load LADSPA plugin and use it globaly.
    Problem here is that I found only one LADSPA Impulse convolver plugin in Steve Harris plugins and this plugin comes with preset impulses so common user can't customize it.
    I downloaded source code, and thought that I could maybe include my impulse in it, then compile it, but format of this impulses is unknown to me as I'm not a programmer. My impulse is 32bit PCM WAV while impulses in this package are in a form of number arrays in C header files (link) so I can't find my way there. If I knew this format rules, than I guess it wouldn't be hard for me to represent my impulse following convention.
    I tried to contact Steve by mail (which is encouraged on his portal) but my mail was rejected as reported by Google Mail
  2. Brutefir
    This could be another possible solution, but...
    Home page was inaccessible so I used cached view to read boring documentation without single usage example. After that I searched Google for possible example usage and found some "specialized" examples that shred a bit of light about it, but I couldn't find anything about the meaning of .brutefir_convolver configuration file.
    This project seems discontinued and I don't know if it is good idea even if I knew how to set it
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What if you try to use a real time kernel for this?. –  Uri Herrera Sep 9 '11 at 7:14
    
Could you elaborate, please? –  zetah Sep 9 '11 at 10:04
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2 Answers 2

I'll post my last comment as answer as I give up from expected solution

  • I found Steve on github and it turned out that format of this impulses included in his plugins source as header files is simple single channel normalized PCM data array.
    I replaced one of provided impulses with mine, changed two more files to accept new impulse name and successively compiled it, installed it and then test it in Audacity.
    Real world wanted to show it's face. Setting module-ladspa-sink was pain. Why does it has to be so complicated? Instead I added Impulse Convolver LADSPA plugin in my .asoundrc file and rebooted.
    Result was disappointing - sound was awful and volume fluctuating. I later found that Impulse Convolver is one of rare plugin that's not RT capable? Damn!? - It comes with preset impulses, it's mono and on top of that can't be used in real time

Conclusion: If we exclude possibility that Brutefir can be set as convolver, then except jack_convolver there is no real Linux plugin that can provide "the mother of all effects" - Convolution

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Just use jack + jconvolver

Instructions to get pulseAudio to pass everything through to Jack here:

http://trac.jackaudio.org/wiki/WalkThrough/User/PulseOnJack

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You could also use brutefir via jack - but jconvolver has lower CPU usage, doing the job via the more efficient fourier means, rather than by brute force convolution. (Brute force is more efficient only for very short impulse responses). –  RGD2 Dec 27 '13 at 5:53
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