1 files changed, 31 insertions, 0 deletions
diff --git a/spa/plugins/audioconvert/crossover.h b/spa/plugins/audioconvert/crossover.h
new file mode 100644
index 0000000..b6f458b
--- /dev/null
+++ b/spa/plugins/audioconvert/crossover.h
@@ -0,0 +1,31 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef CROSSOVER_H_
+#define CROSSOVER_H_
+
+#include <stdbool.h>
+
+#include "biquad.h"
+/* An LR4 filter is two biquads with the same parameters connected in series:
+ *
+ * x -- [BIQUAD] -- y -- [BIQUAD] -- z
+ *
+ * Both biquad filter has the same parameter b[012] and a[12],
+ * The variable [xyz][12] keep the history values.
+ */
+struct lr4 {
+	struct biquad bq;
+	float x1, x2;
+	float y1, y2;
+	float z1, z2;
+	bool active;
+};
+
+void lr4_set(struct lr4 *lr4, enum biquad_type type, float freq);
+
+void lr4_process(struct lr4 *lr4, float *dst, const float *src, const float vol, int samples);
+
+#endif /* CROSSOVER_H_ */