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-rw-r--r--docs/manual/advanced-dataaccess.xml87
1 files changed, 86 insertions, 1 deletions
diff --git a/docs/manual/advanced-dataaccess.xml b/docs/manual/advanced-dataaccess.xml
index 774f06782..28fc56ca3 100644
--- a/docs/manual/advanced-dataaccess.xml
+++ b/docs/manual/advanced-dataaccess.xml
@@ -1050,14 +1050,99 @@ main (int argc, char *argv[])
</para>
<para>
Below is an example of how you can change the caps of a pipeline
- while in the PLAYING state.
+ while in the PLAYING state:
</para>
<programlisting>
<!-- example-begin dynformat.c -->
<![CDATA[
+#include <stdlib.h>
+
+#include <gst/gst.h>
+
+#define MAX_ROUND 100
+
+int
+main (int argc, char **argv)
+{
+ GstElement *pipe, *filter;
+ GstCaps *caps;
+ gint width, height;
+ gint xdir, ydir;
+ gint round;
+ GstMessage *message;
+
+ gst_init (&argc, &argv);
+
+ pipe = gst_parse_launch_full ("videotestsrc ! capsfilter name=filter ! "
+ "ximagesink", NULL, GST_PARSE_FLAG_NONE, NULL);
+ g_assert (pipe != NULL);
+
+ filter = gst_bin_get_by_name (GST_BIN (pipe), "filter");
+ g_assert (filter);
+
+ width = 320;
+ height = 240;
+ xdir = ydir = -10;
+
+ for (round = 0; round < MAX_ROUND; round++) {
+ gchar *capsstr;
+ g_print ("resize to %dx%d (%d/%d) \r", width, height, round, MAX_ROUND);
+
+ /* we prefer our fixed width and height but allow other dimensions to pass
+ * as well */
+ capsstr = g_strdup_printf ("video/x-raw, width=(int)%d, height=(int)%d",
+ width, height);
+
+ caps = gst_caps_from_string (capsstr);
+ g_free (capsstr);
+ g_object_set (filter, "caps", caps, NULL);
+ gst_caps_unref (caps);
+
+ if (round == 0)
+ gst_element_set_state (pipe, GST_STATE_PLAYING);
+
+ width += xdir;
+ if (width >= 320)
+ xdir = -10;
+ else if (width < 200)
+ xdir = 10;
+
+ height += ydir;
+ if (height >= 240)
+ ydir = -10;
+ else if (height < 150)
+ ydir = 10;
+
+ message =
+ gst_bus_poll (GST_ELEMENT_BUS (pipe), GST_MESSAGE_ERROR,
+ 50 * GST_MSECOND);
+ if (message) {
+ g_print ("got error \n");
+
+ gst_message_unref (message);
+ }
+ }
+ g_print ("done \n");
+
+ gst_object_unref (filter);
+ gst_element_set_state (pipe, GST_STATE_NULL);
+ gst_object_unref (pipe);
+
+ return 0;
+}
]]>
<!-- example-end dynformat.c -->
</programlisting>
+ <para>
+ Note how we use <function>gst_bus_poll()</function> with a
+ small timeout to get messages and also introduce a short
+ sleep.
+ </para>
+ <para>
+ It is possible to set multiple caps for the capsfilter separated
+ with a ;. The capsfilter will try to renegotiate to the first
+ possible format from the list.
+ </para>
</sect2>
</sect1>