Subject: Re: [linux-audio-dev] XAP status : incomplete draft
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri Dec 13 2002 - 16:08:13 EET
Generally I agree with David, but there are a few things wher I dont:
On Fri, Dec 13, 2002 at 02:30:32 +0100, David Olofson wrote:
> > * The label is a file-unique, non-whitespace, string identifier
> > for * the plugin. Hosts can use the filename and label to identify
> > a * plugin uniquely. The label is all upper case, by convention.
> > */
> > const char *xap_label;
>
> Why is this needed? (There are unique IDs, I mean...)
LADSPA has them and its useful sometime, eg. for selecting plugins in
command line apps, and for developers.
> > void *(*xap_create)(XAP_descriptor *descriptor, XAP_host *host,
> > int rate);
>
> Why only "rate" here - or rather, why "rate" at all? I think there
> are more things that a Plugin might want to know, so it might be
> better to pass this kind of info some other way.
Well, you might want to refuse to instantiate, based on the sample rate.
> > /*
> > * set_rate: set the sample rate
> > *
> > * This method may only be called on plugins that are not active.
>
> (Same thing as controls that may only be changed in certain states.)
This should not be allowed, if you want to run the instrument at a
different rate, reinstantiate it.
> > #define XAP_RTFL_SLOW 0x20 /* is 'slow' in general */
>
> Well, everything is relative...
>
> I think it would be much more interesting to have a warning hint for
> plugins that are significantly nondeterministic in their CPU usage.
Agreed. I think tis less confusing to have to indicate that a plugin /is/
deterministic though.
Don't do what ladspa did though and mix together RT safe-ness and
determinicity (is that a real word?).
> > #define XAP_CTRLHINT_PITCH "PITCH" //channel,voice
>
> ...and the optional "NOTE_PITCH" that no one will ever use, of
> course. ;-)
And many of us still think doesn't belong in the API... :)
- Steve
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