1 May
2006
1 May
'06
7:40 a.m.
On Mon, May 01, 2006 at 02:13:00AM +0200, Lars Luthman wrote:
Control port :|
Not really - plugins only get to write to the control ports in the run()
callback (or select_program() for DSSIs), and it's entirely possible and
plausible that a program would want to list the available programs for a
plugin before it starts running it's audio callback.
I as thinking the host could call run(0), but I guess it might not want to
activate either.
2) the
dynamic program lists and midi mappings (static definitions
could be written in the RDF file, but that's no fun)
That's a tougher one. Would it be possible to change the instantiation
function from
LADSPA_Handle (*instantiate)(const LADSPA_Descriptor* Descriptor,
unsigned long SampleRate,
const char* BundlePath,
const char** HostFeatures);
to something like this:
LADSPA_Handle (*instantiate)(const LADSPA_Descriptor* Descriptor,
unsigned long SampleRate,
const char* BundlePath,
const char** HostFeatures,
void** HostFeatureData);
where HostFeatureData is a NULL-terminated array of the same size as
HostFeatures, containing feature-specific data that the plugin can read
and/or write. Then, if HostFeatures[3] is "PROGRAM_LIST_CALLBACK",
HostFeatureData[3] can point to a 'const DSSI_Program_Descriptor
*(*)(LADSPA_Handle, unsigned long)', i.e. a DSSI program list callback
pointer, and the plugin can set it to point to its program list
callback. Or you could define a "DSSI" host feature and a struct similar
to the current DSSI_Descriptor with configure(), get_programs(),
get_midi_controller_for_port() etc and pass a pointer to that instead.
It's possible, but it looks a bit ugly to me, and theres no way to update
it without calling instantiate again.
I don't see any other obvious way to let future
extensions add their own
callbacks (except for specifying a function name in the RDF file and
then dlsym()ing that symbol name in the host).
Or passing function poionters over control outs, but thats even nastier.
But if its a required host feature, then the mini-spec for the feature can
just say what the callback must be called.
- Steve