[linux-audio-dev] LADSPA port hints again!

Steve Harris S.W.Harris at ecs.soton.ac.uk
Sat Aug 23 13:19:18 UTC 2003


On Sat, Aug 23, 2003 at 04:40:45 +0100, Mike Rawes wrote:
> Hi,
> 
> Back in March it was suggested that some additional hints should be
> added to LADSPA - there was some discussion, but nothing since. Here's
> what I gathered from the archives:

Thanks for doing that.
 
> /* Hint OUTPUT_METER indicates that the value of output
>    control port is likely to be most meaningful to the user if
>    displayed as a meter.  Can be combined with LADSPA_HINT_LOGARITHMIC
>    if the meter should use a log scale. (e.g. dB)
> */
> #define LADSPA_HINT_OUTPUT_METER    0x??

I'm happy about the others but this one wasn't really discussed much. My
feeling is that there are 3 common uses for control output ports.

a) its meant to be sent to something else and rendering it isn't
   particularly helpful

b) its meant to be shown numerically

c) its meant to be show graphically (a meter or similar).

I think a more generic mechanism might be

LADSPA_HINT_OUTPUT_NUMERIC
LADSPA_HINT_OUTPUT_GRAPHIC

if neither of these is set the implication would be that theres nothing
useful to display there. They could possibly be allowed on input ports
too.

Another possible hint could be something like
LADSPA_HINT_INSTANTIATION_TIME or something like that which hints that a
port is only listented to at instantiation time - eg. a maximum delay
time, that causes a malloc during instantiate(). 

A host following this hint could present the choices to the user when they
add the plugin and not show that port in the interactive UI.

I could happly live without the last one, but I've been given plugins that
really need it.

- Steve



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