gboolean (*set_meta) (GstPreset *preset, const gchar *name,
const gchar *tag, const gchar *value);
gboolean (*get_meta) (GstPreset *preset, const gchar *name,
gboolean (*set_meta) (GstPreset *preset, const gchar *name,
const gchar *tag, const gchar *value);
gboolean (*get_meta) (GstPreset *preset, const gchar *name,