audio: make softvol scale cubic

This brings the volume control closer to what is percepted as linear
volume change.

Adjust the --softvol-max default to roughly the old maximum (roughly
doubles the gain).

1 files changed, 5 insertions, 2 deletions

diff --git a/audio/filter/af_volume.c b/audio/filter/af_volume.c
index a0b47e7438..dfdf586690 100644
--- a/audio/filter/af_volume.c
+++ b/audio/filter/af_volume.c
@@ -30,6 +30,7 @@
 #include "demux/demux.h"
 
 struct priv {
+    float vol;                  // User-specified non-linear volume
     float level;                // User-specified gain level for each channel
     float rgain;                // Replaygain level
     int rgain_track;            // Enable/disable track based replaygain
@@ -87,10 +88,12 @@ static int control(struct af_instance *af, int cmd, void *arg)
         return af_test_output(af, in);
     }
     case AF_CONTROL_SET_VOLUME:
-        s->level = *(float *)arg;
+        s->vol = *(float *)arg;
+        s->level = pow(s->vol, 3);
+        MP_VERBOSE(af, "volume gain: %f\n", s->level);
         return AF_OK;
     case AF_CONTROL_GET_VOLUME:
-        *(float *)arg = s->level;
+        *(float *)arg = s->vol;
         return AF_OK;
     }
     return AF_UNKNOWN;