Convert elements to use gst_pad_use_explicit_caps() where appropriate.

Original commit message from CVS:
Convert elements to use gst_pad_use_explicit_caps() where appropriate.

ext/ffmpeg/gstffmpegdec.c

@@ -179,6 +179,7 @@ gst_ffmpegdec_init (GstFFMpegDec *ffmpegdec)
   gst_pad_set_link_function (ffmpegdec->sinkpad, gst_ffmpegdec_connect);
   gst_pad_set_chain_function (ffmpegdec->sinkpad, gst_ffmpegdec_chain);
   ffmpegdec->srcpad = gst_pad_new_from_template (oclass->srctempl, "src");
+  gst_pad_use_explicit_caps (ffmpegdec->srcpad);
 
   gst_element_add_pad (GST_ELEMENT (ffmpegdec), ffmpegdec->sinkpad);
   gst_element_add_pad (GST_ELEMENT (ffmpegdec), ffmpegdec->srcpad);
@@ -410,7 +411,7 @@ gst_ffmpegdec_chain (GstPad    *pad,
         caps = gst_ffmpeg_codectype_to_caps (oclass->in_plugin->type,
 					     ffmpegdec->context);
         if (caps == NULL ||
-            gst_pad_try_set_caps (ffmpegdec->srcpad, caps) <= 0) {
+            !gst_pad_set_explicit_caps (ffmpegdec->srcpad, caps)) {
           gst_element_error (GST_ELEMENT (ffmpegdec),
 			     "Failed to link ffmpeg decoder (%s) to next element",
 			     oclass->in_plugin->name);

ext/ffmpeg/gstffmpegdemux.c

@@ -316,6 +316,7 @@ gst_ffmpegdemux_loop (GstElement *element)
     pad = gst_pad_new_from_template (templ, padname);
     g_free (padname);
 
+    gst_pad_use_explicit_caps (pad);
     /* FIXME: convert() and query() functions for pad */
 
     /* store pad internally */
@@ -325,12 +326,9 @@ gst_ffmpegdemux_loop (GstElement *element)
     /* get caps that belongs to this stream */
     caps = gst_ffmpeg_codecid_to_caps (st->codec.codec_id,
 				       &st->codec);
-    if (gst_pad_try_set_caps (pad, caps) <= 0) {
-      GST_DEBUG (
-		 "Failed to set caps from ffdemuxer on next element");
-      /* we continue here, in the next pad-is-usable check,
-       * we'll return nonetheless */
-    }
+    gst_pad_set_explicit_caps (pad, caps);
+    /* we continue here, in the next pad-is-usable check,
+     * we'll return nonetheless */
   }
 
   /* shortcut to pad belonging to this stream */