Subject: Re: [linux-audio-dev] finding the selection length with LADSPA
From: douglas irving repetto (douglas_AT_music.columbia.edu)
Date: Thu Oct 19 2000 - 01:25:28 EEST
David Benson wrote:
>
> > yes, it seems like it's a problem if it's impossible to implement a fade
> > in/out filter that operates on a user selection. requiring a user to
> > type in a number of samples to fade over is kind of old skool, and is
> > redundant if the user has already selected a region. i can think of many
> > cases where it's necessary to know the total number of samples selected
> > before beginning the processing.
>
> may i suggest making the fade time be a parameter
> of the filter? (an input control parameter)
>
> in a streaming context, that's really all you can do:
> ladspa does not model the end of a stream.
i can see how that would work. but it seems like that's putting the user
in a position where they need to know things that the host may not be
telling them.
for instance, when i work with an editor (like peak on the mac) and i
want to do a fade, i simply select some audio and run the fade in filter
on it. i'm not thinking about how long the selection is or how many
samples there are or anything like that. and depending on how the gui is
set up, i may or may not have any way to get at that information anyway.
what i do know is that i've selected (visually) the exact region that i
want faded. i guess that an intelligent host program could fill in a
default value for me, one that is equal to the length my current
selection. but there's no way to enforce that behaviour.
it seems to me that an awful lot of filter-type operations are most
conveniently handled by a simple "select the region and run the filter"
model. and for any process that requires parameters to move from one
value to another over the run of the process, the plugin needs to know
the total number of samples that have been selected. having a user type
in a time parameter could be both awkward and potentially inaccurate.
then again, i'm still just getting to know LADSPA, so please if i've
missed something or said something dumb let me know!
in the mean time, i'll implement the fade filter with david's suggestion
above.
thanks,
douglas
--
douglas irving repetto
http://music.columbia.edu/~douglas
the music-dsp mailing list and website:
http://shoko.calarts.edu/musicdsp
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