Re: [linux-audio-dev] ladspa GUI spec status?

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Subject: Re: [linux-audio-dev] ladspa GUI spec status?
From: Conrad Parker (conrad_AT_vergenet.net)
Date: Fri Feb 23 2001 - 07:37:37 EET


On Fri, Feb 23, 2001 at 02:14:52AM +0000, pcburns_AT_mail.zip.com.au wrote:
> > On Thu, Feb 22, 2001 at 03:32:14PM +1100, Conrad Parker wrote:
> > I have an idea for a plugin that needs to load a pcm file when it
> > starts, poping up a file load diaglog is the only sane thing I
> > could think of.
>
> I think that LADSPA needs to be given some extended functionality. There should
> be input and output control ports that can be used to pass strings to and from
> the plugin. This could enable plugins for reading and writing sample file
> formats. Or perhaps plugins that take the audio input and write it out
> to /dev/dsp or where ever.

what Sweep does in this situation (for its native plugins) is:
        - it has a 'string' datatype for plugin parameters
        - you can optionally set 'hints' on paramters; one of these is
          SW_PARAM_HINT_FILENAME, which hints to the application that it
          could bring up a file request dialog box to get this string
          argument.

this is much like how LADSPA provides hints for ports which should be
interpreted as sample rates, or should be interpreted logarithmically. It
means that the plugins don't have to care about providing dialogs for them;
it would get really messy if each plugin had its own way of getting
logarithmic data, and it would also get ugly if each plugin had its own
file requesters.

anyway, that's just a suggestion. More info on Sweep's hints and other
datatypes at http://sweep.sourceforge.net/doc/plugin_writers_guide.txt

I think it's really important that, as much as possible, plugins don't
provide their own gui code but instead provide semantic hints about what
sort of data they want -- then the apps using the plugins can bring up
appropriate dialogs using their own toolkit or whatever. (eg. there's no
reason LADSPA plugins shouldn't be able to work inside a console
environment, or within a custom SVGA tool, or whatever ...)

Conrad.


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