[gst-devel] Re: dparams roadmap (AKA dparams are dead, long live control pads)

Steve Baker steve at stevebaker.org
Mon Mar 7 14:00:35 CET 2005

The best way to implement polyphonic elements might be to do the following:
- create a monophonic element with whatever behaviours and dynamic parameters
- create a polyphonic bin element which creates a pool of X number of
monophonics elements and mixes the results into a single src pad
- when you want to play a note, iterate over the monophonic elements until
you find one that is not making noise, then set its parameters to play

Then the problem of adding/removing object properties goes away. You could
also do very clever things within the bin such as having each monophonic
element being attached to its own chain of effects before being mixed


> Hi Edward,
> the biggest conceptional problem is currently have is that in my last
> mail in the thread - multiple voices.
> There is currently a thread in the glib list about dynamically
> adding/removing object properties.
> And one thing they brought to my attention is that gobject prooperties
> are installed class wide.
> The number of voice an plugin supports is a property of the instance
> though.
> With current dparams and with the control pad approach, it would be
> possible to do it as these act on a object instance.
> I have no good idea yet how to do this, when using gobject properties.
> a.) allocating e.g. 10 sets of parameters and keeping a number of
> 'voices used'.
> requires to use a GInterface, that tells about the special property to
> use to control the number of voices.
> b.) setting a current-voice property first and use this when the voice
> properties are addressed
> switch (property_id) {
>     current_voice=g_value_get_long(value);
>     break;
>     note[current_voice]=g_value_get_long(value);
>     break;
> }
> Bahhh, wouldn't work nicely with the envelopes ...
> Stefan
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