link: improve renegotiation

Only suspend an idle node when we need to configure a different format.

spa/lib/format.h

@@ -0,0 +1,40 @@
+/* Simple Plugin API
+ * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __SPA_LIBFORMAT_H__
+#define __SPA_LIBFORMAT_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <spa/props.h>
+
+int spa_format_filter(const struct spa_format *format,
+		      const struct spa_format *filter,
+		      struct spa_pod_builder *result);
+
+int spa_format_compare(const struct spa_format *format1,
+		       const struct spa_format *format2);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __SPA_LIBFORMAT_H__ */