<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
><HEAD
><TITLE
>Changing Dynamic Parameter Values</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="HOME"
TITLE="GStreamer Application Development Manual"
HREF="index.html"><LINK
REL="UP"
TITLE="Dynamic Parameters"
HREF="chapter-dparams.html"><LINK
REL="PREVIOUS"
TITLE="Creating and Attaching Dynamic Parameters"
HREF="section-dparams-creating.html"><LINK
REL="NEXT"
TITLE="Different Types of Dynamic Parameter"
HREF="section-dparams-types.html"></HEAD
><BODY
CLASS="sect1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
><SPAN
CLASS="application"
>GStreamer</SPAN
> Application Development Manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="section-dparams-creating.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 30. Dynamic Parameters</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="section-dparams-types.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="section-dparams-changing"
>30.3. Changing Dynamic Parameter Values</A
></H1
><P
> All interaction with dparams to actually set the dparam value is done through simple GObject properties.
There is a property value for each type that dparams supports - these currently being
<TT
CLASS="filename"
>"value_float"</TT
>, <TT
CLASS="filename"
>"value_int"</TT
> and <TT
CLASS="filename"
>"value_int64"</TT
>.
To set the value of a dparam, simply set the property which matches the type of your dparam instance.
</P
><PRE
CLASS="programlisting"
> #define ZERO(mem) memset(&mem, 0, sizeof(mem))
...
gfloat set_to_value;
GstDParam *volume;
GValue set_val;
ZERO(set_val);
g_value_init(&set_val, G_TYPE_FLOAT);
...
g_value_set_float(&set_val, set_to_value);
g_object_set_property(G_OBJECT(volume), "value_float", &set_val);
</PRE
><P
>Or if you create an actual GValue instance:</P
><PRE
CLASS="programlisting"
> gfloat set_to_value;
GstDParam *volume;
GValue *set_val;
set_val = g_new0(GValue,1);
g_value_init(set_val, G_TYPE_FLOAT);
...
g_value_set_float(set_val, set_to_value);
g_object_set_property(G_OBJECT(volume), "value_float", set_val);
</PRE
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="section-dparams-creating.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="section-dparams-types.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Creating and Attaching Dynamic Parameters</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="chapter-dparams.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Different Types of Dynamic Parameter</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
