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docs: update controller design doc

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Stefan Sauer 2012-01-01 20:59:22 +01:00
parent 33e381743b
commit 5668654ed5
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docs/design/part-controller.txt
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@ -12,12 +12,25 @@ Elements don't need to do much. They need to:
GST_PARAM_CONTROLLABLE GST_PARAM_CONTROLLABLE
- call gst_object_sync_values (self, timestamp) in the processing function - call gst_object_sync_values (self, timestamp) in the processing function
before accessing the parameters. before accessing the parameters.
All ordered property types can be automated (int, double, boolean, enum).
Application view Application view
~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~
Application need to setup the property automation. For that they need to create Applications need to setup the property automation. For that they need to create
a GstControlSource and attach it to a property using GstControlBinding. Various a GstControlSource and attach it to a property using GstControlBinding. Various
control-sources and control-bindings exists. All control sources produce control control-sources and control-bindings exist. All control sources produce control
value sequences in the form of gdouble values. The control bindings map them to value sequences in the form of gdouble values. The control bindings map them to
the value range and type of the bound property. the value range and type of the bound property.
One control-source can be attached to one or more properties at the same time.
If it is attached multiple times, then each control-binding will scale and
convert the control values to the target property type and range.
One can create complex control-curves by using a GstInterpolationControlSource.
This allows the classic user editable control-curve (often seen in audio/video
editors). Another way is to use computed control curves. GstLFOControlSource can
generate various repetitive signals. Those can be made more complex by chaining
the control sources. One can attach another control-source to e.g. modulate the
frequency of the first GstLFOControlSource.