add support for dB volumes

[pulseaudio] / polyp / sample.c

diff --git a/polyp/sample.c b/polyp/sample.c
index edfe195941623fe1ee208a9be96898df23e3ef36..3019f93b872245402087eac210c594553b9b7629 100644 (file)
--- a/polyp/sample.c
+++ b/polyp/sample.c
@@ -25,6 +25,7 @@
 
 #include <stdio.h>
 #include <assert.h>
+#include <math.h>
 
 #include "sample.h"
 
@@ -104,3 +105,17 @@ pa_volume_t pa_volume_multiply(pa_volume_t a, pa_volume_t b) {
 
     return (pa_volume_t) p;
 }
+
+pa_volume_t pa_volume_from_dB(double f) {
+    if (f <= -200)
+        return PA_VOLUME_MUTED;
+
+    return (pa_volume_t) (pow(10, f/20)*PA_VOLUME_NORM);
+}
+
+double pa_volume_to_dB(pa_volume_t v) {
+    if (v == PA_VOLUME_MUTED)
+        return -200;
+
+    return 20*log10((double) v/PA_VOLUME_NORM);
+}