[music-dsp] Re: J. Dattorro and filters webpage

Richard Dobson RWD at cableinet.co.uk
Tue Jul 17 04:52:13 EDT 2001

You shouldn't need to have a get_parameter_range() method. Just require
that all paramters are treated by the outside world as in one range, say
0 to 1 floats, and the plugin can remap that range to whatever it wants,
internally. The VST system of returning a string representing the 'real'
value and units, such as "-24dB" works very well. A key advantage of
this rule, which is important to me, anyway, is that any external
automation signal can be applied simultaneously to multiple plugin
parameters in multiple plugins. If each parameter demands a custom
range, this becomes impossible. Of course, if the range information is
just that, informative, that's OK; but the streaming parameter values
should all be within one universally dictated range. 

The other interesting issue I am looking at is multi-dimensional
parameters; e.g positional audio (spherical coordinates, for example),
and even basic amp/freq parameters for oscillators. Again, this sort of
thing becomes much easier if one can define such things formally, as you
would do for a file format. Having a get_dimension() method, with an
opaque format, isn't going to be much help, as a host can have no idea
what to do with it; especially with respect to display.

But overall I suspect that the goal of loose coupling between the host
and a plugin inevitably means that some things cannot be done; which is
why a plugin sometimes needs it's own GUI/user interface.

Richard Dobson

Jon Watte wrote:
> One thing often missing in APIs of this kind (and drivers, and whatnot) is
> the necessary meta-data to properly configure the thing from a host that
> doesn't know about it a priori. Thus I would argue that not only do you need
> set_parameter(what, value) but you need count_parameters(),
> get_parameter_name(what), get_parameter_type(what) and
> get_parameter_range(what, float*, float*). The last three can be put in a
> single get_parameter_info(what) which returns a struct/union.

Test your DAW with my Soundcard Attrition Page!
http://www.bath.ac.uk/~masrwd (LU: 3rd July 2000)
CDP: http://www.bath.ac.uk/~masjpf/CDP/CDP.htm (LU: 23rd February 2000)

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