[linux-audio-dev] Project: modular synth editor

Matthias Nagorni mana at suse.de
Thu Jan 15 15:41:40 UTC 2004


On Wed, 14 Jan 2004, Dave Robillard wrote:

> Quick digression about LADSPA in ams:  is there a reason exported

For a solution and statement as to the future of ams see below...

> control ports on LADSPA plugins don't work (at least for me anyway)?  I
> realize control ports run at a different rate than the audio, but since
> the ports are exported I figured this would be taken care of.
>
> I should probably take this to the ams list, but here's a test case:
>
> MCV Frequency -> Converter (V/Oct to Hz) -> LADSPA Analog Oscillator
> Frequency -> Output
>
> (Analog oscillator is I believe from plugin.org.uk, you almost certainly
> have it.)  Anyway..

I just checked it out. The problem is solved by choosing the right
conversion mode in the converter module (V/Octave --> 0..1, 1=rate/2).
So it seems like the exported LADSPA control ports do work. Note that
the voltages of the GUI slider and the exported port are added, therefore
you need to set the Frequency slider to 0 in your case.

> After posting my intial message I thought a bit more about AMS.. it's
> true, it's so close to what I need modifying it is probably wisest..
[...]
> despite that most wretched of widget sets QT and that brown color I
> can't erase from my mind (I kid! :) ).
[...]

Before giving a statement about the past, present and future of ams, I'd
like to mention that Fons has made the colors configurable in main.h,
therefore you are invited to come up with an alternate color scheme ;-)

Now about history and future of ams and why I recommend to rewrite it
from scratch:

My intention behind ams was to implement a simple softsynth with full
MIDI control that is easily operated so that average computer users
can immediately have fun with it. It was more meant to form a demo
for sliders controlled via ALSA MIDI sequencer than a project of the size
that it has now taken. In the beginning I could not even dream of the
sound quality that Fons has brought to the project through his LADSPA plugins.
The current ams seems to have reached it's goal: The current issue of
german Keyboards publishes a 2 page article on ams and linux audio
(written by me) and also 9 MP3s on their download page (www.keyboards.de,
enter 402124 in the Web+ field to access them). So ams makes "mainstream"
audio people aware of Linux software synthesis. BTW the article has also
large link box with pointers to Dave's page, some projects and the LAD page.

Many useful proposals (e.g. polyphony change at runtime, distinction
between control and audio ports so that control data can behandled at
1/16 audio rate which improves speed a lot, distict audio and gui part)
can not easily be realized within the current design. Moreover at least
a part of the source has been written quite in a hurry so that it is not
very clean.
A rewrite does not at all mean that the effort which has gone into ams is
wasted. One can learn from ams and maybe even copy some code from it.
However I would suggest to envisage a larger scale project now in the way
that Fons has suggested.

Matthias

-- 
Dr. Matthias Nagorni
SuSE Linux AG
Maxfeldstr. 5             phone: +49 911 74053375
D - 90409 Nuernberg       fax  : +49 911 74053483






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