af_volume: add detach option

Maybe this should be default. On the other hand, this filter does
something even if the volume is neutral: it clips samples against the
allowed range, should the decoder or a previous filter output garbage.

1 files changed, 4 insertions, 0 deletions

diff --git a/audio/filter/af_volume.c b/audio/filter/af_volume.c
index 4abbded822..31f9653e6f 100644
--- a/audio/filter/af_volume.c
+++ b/audio/filter/af_volume.c
@@ -39,6 +39,7 @@ struct priv {
     int rgain_clip;             // Enable/disable clipping prevention
     int soft;                   // Enable/disable soft clipping
     int fast;                   // Use fix-point volume control
+    int detach;                 // Detach if gain volume is neutral
     float cfg_volume;
 };
 
@@ -136,6 +137,8 @@ static int control(struct af_instance *af, int cmd, void *arg)
                     s->rgain = MPMIN(s->rgain, 1.0 / peak);
             }
         }
+        if (s->detach && fabs(s->level + s->rgain - 1.0) < 0.00001)
+            return AF_DETACH;
         return af_test_output(af, in);
     }
     case AF_CONTROL_SET_VOLUME:
@@ -209,6 +212,7 @@ struct af_info af_info_volume = {
         OPT_FLAG("replaygain-clip", rgain_clip, 0),
         OPT_FLAG("softclip", soft, 0),
         OPT_FLAG("s16", fast, 0),
+        OPT_FLAG("detach", detach, 0),
         {0}
     },
 };