[linux-audio-dev] LADSPA Hosting

Steve Harris S.W.Harris at ecs.soton.ac.uk
Thu Apr 17 14:38:01 UTC 2003

On Thu, Apr 17, 2003 at 12:25:33PM -0400, Nick Tsocanos wrote:
> I am going to make my Moog filter into a plugin as my first attempt. I
> think it sounds pretty good and the resonance is really good on it. I
> modeled it directly from the analog-s-domain transfer function given by
> stilson using a bilinear transform, and double sample it for stability.
> It appears it only works properly if the coefficients are doubles.

Its notmal for filters to be unstable if you use floats internally, you
can sometimes get away with it if you clamp the cutoff.

> I have figured out mostly what the problem was with unitialized plugins.
> The problem is I was not zeroing out my controlPorts when creating the
> plugin, and it would come up with whacky values. Only some plugins don't
> work correctly. Most work ok even with random values (but they make
> really really strange sounds).

Yup, strange sounds are to be expected :) If they blow up then its a bug
> Also, I think that on some plugins, it expects input to be normalized to
> [-1,1] and, I am not clipping at the point I run the plugins, because I
> am using a dither() algorithm which does the hard clipping when quantize
> to 16-bit integers (for sound output).

Again, they shouldstill work, but might sound wierd.
> Don't think I am criticizing any plugins!

No, please do there are a lot of undicovered bugs.

- Steve

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