glmixer: ensure caps are writable after intersection

gst_caps_intersect () may return an increased reference of one of the
input caps.

Fixes critical in the simple-launch-lines test:

Unexpected critical/warning: gst_caps_set_features: assertion 'IS_WRITABLE (caps)' failed

diff --git a/ext/gl/gstglmixer.c b/ext/gl/gstglmixer.c
index 9a7446a..b8f4da0 100644 (file)
--- a/ext/gl/gstglmixer.c
+++ b/ext/gl/gstglmixer.c
@@ -224,6 +224,7 @@ _update_caps (GstVideoAggregator * vagg, GstCaps * caps, GstCaps * filter)
 
   if (filter) {
     tmp = gst_caps_intersect (caps, filter);
+    tmp = gst_caps_make_writable (tmp);
   } else {
     tmp = gst_caps_copy (caps);
   }