[gst-devel] GValue event networks in GStreamer

[Steve Baker]

On Fri, 2004-07-23 at 13:28, Josh Green wrote:
> On Thu, 2004-07-22 at 15:49, Steve Baker wrote:
> > See my previous dparams email about mapping between GstStructure and
> > GParamSpecs - maybe we could put a convenience function in core to convert
> > a GstStructure with the required data to a GParamSpec.
> > 
> 
> I had a look at libs/gst/control/dparam.[ch] but I'm still somewhat
> clueless as to what these are for. "Dynamic parameter functionality"
> helps a little bit. Any pointers where I can find out more about
> dparams?

Basically dparams are attached directly to elements and data structures
are defined which describe how that parameter should change over time.
Common examples would be:
- a smoothing dparam which smooths out the rapid movements of a gui
slider
- a timelined dparam which interpolates between points on a timeline
- an oscillator which constantly changes the dparam based on some unit
function
 
> > At first glance it looks like dparams and control pads are duplicated
> > effort trying to solve the same problems.
> 
> When you say "control pads" are you referring to the GValue event
> network stuff that is the topic of this thread or are you referring to
> some other existing sub system in GStreamer?

I'm talking about a GValue event network

> > I think in many cases creating an element and building a network just to
> > send around some control values will be too heavy-weight for many
> > situations. In other cases it would be the right thing.
> > 
> 
> Heavy weight as in data allocation overhead? Essentially I'm just trying
> to help create a way for routing arbitrary GValue data (values and
> events) which could then encapsulate boxed structures such as a MIDI
> event union, etc. I would love to leverage off of any existing GStreamer
> subsystems that make sense for this task.
> 
> I have yet to hear any objections for a new GValue GstData type, so
> perhaps its a good idea? :)

I'm all in favour of what your doing, but I'm not currently enough of a
core developer to give the official blessing.
 
-- 
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Steve Baker
Silvereye Software Consulting
steve at stevebaker.org
+64 (0)21 344 066
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