Re: [linux-audio-dev] Re: Software controller for homemade edrums

> Message: 10
> Date: Wed, 08 Jun 2005 15:57:23 +0200
> From: Olivier Guilyardi <ml@email-addr-hidden>
> Subject: Re: [linux-audio-dev] Re: Software controller for homemade
>         edrums
> To: "The Linux Audio Developers' Mailing List"
>         <linux-audio-dev@email-addr-hidden>
> Message-ID: <42A6F943.4080606@email-addr-hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi Florian,
>
> Florian Schmidt wrote:
> >For quick tests without libDSP you can tweak the jack_convolve Makefile
> >a little:
> >
> >uncomment the
> >
> >#COMPILE_FLAGS += -DC_CMUL
> >
> >line and remove "-ldsp" from the LINK_FLAGS line. This will use an
> >unoptimized C complex multiplication implementation. jack_convolve will
> >use around 10-20% more cpu than with the libDSP implementation.
> >
> >  
>
> It did compile. I also needed to remove the #include <dsp/dspop.h> in
> convolve.c
>
> Okay, so I now have an idea of what convolution is. Your little piece of
> software is very nice, very easy to understand. I used three samples : a
> bassdrum, a snare drum, and a short guitar chord. I plugged the output
> of one of my pads into jack_convolve's input and its output into the
> alsa_pcm playback.
>
> Both the bassdrum and the chord sounded quite nice. But the snare drum
> sounded like very far away. I guess this comes from the silence at the
> end of this sample.
>
> What exactly happens with these "response files" ? Should I use very
> simple samples, like a sine wave with no silence ? Shouldn't convolving
> be coupled with trigerring ? I mean : hitting the pad would start the
> sample playback, and the convolving engine would use both this sample
> playback and the pad signal to produce its output. In this case,
> jack_convolve would then need one output and two inputs :
> - one for the pad signal,
> - and one for the "response signal", that is : the sample playback that
> started right when the pad got hit
>
> Is this possible, or do I misunderstand convolution here ?

Olivier, I think the next step is to run jack_convolve, and connect the
soundcard input directly into jack_convolve's input using qjackctl. then
connect the output of jack_convovle to the soundcard's outputs.
(jack_convolve may already do this for you, I can't check just this moment)

Now when you hit a pad, it should be "convolved" with the response signal
giving you something different than the simple "click" of the input signal.

I'm very interested to see how this works out (I suggested this path to
Olivier, I hope it's not totally worthless :) ). It could be a way to build
a cheap, responsive electronic drum kit that preserves the nuances of the
input signal. I wonder if this is how the Korg Wavedrum worked?

-Ben
Received on Wed Jun 8 20:15:11 2005