media-codecs: Add codec availability check to public API

This will be useful for building a list of preferred audio codecs.

plugins/sip/gst-rfc3551.c

@@ -39,7 +39,13 @@ static MediaCodecInfo gst_codecs[] = {
 };
 
 
-static gboolean
+/**
+ * media_codec_available_in_gst:
+ * @codec: A #MediaCodecInfo
+ *
+ * Returns: %TRUE if codec is available on your system, %FALSE otherwise
+ */
+gboolean
 media_codec_available_in_gst (MediaCodecInfo *codec) {
   gboolean available = FALSE;
   GstRegistry *registry = gst_registry_get ();

plugins/sip/gst-rfc3551.h

@@ -44,6 +44,7 @@ typedef struct {
 } MediaCodecInfo;
 
 
+gboolean         media_codec_available_in_gst (MediaCodecInfo *codec);
 MediaCodecInfo*  media_codec_by_name (const char *name);
 MediaCodecInfo*  media_codec_by_payload_id (uint payload_id);
 gchar*           media_codec_get_gst_capabilities (MediaCodecInfo *codec);