From d6abfcd5784b033803d325b4dbb17836fdf7031e Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Sat, 9 Nov 2013 23:25:31 +0100
Subject: af_volume: use only one volume setting for all channels

In theory, af_volume could use separate volume levels for each channel.
But this was never used anywhere.

MPlayer implemented something similar before (svn r36498), but kept the
old path for some reason.
---
 audio/filter/af_volume.c | 36 ++++++++++++++----------------------
 audio/mixer.c            | 20 ++++++++------------
 2 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/audio/filter/af_volume.c b/audio/filter/af_volume.c
index fa505a3dab..9639ffb5c4 100644
--- a/audio/filter/af_volume.c
+++ b/audio/filter/af_volume.c
@@ -30,7 +30,7 @@
 #include "af.h"
 
 struct priv {
-    float level[AF_NCH];        // Gain level for each channel
+    float level;                // Gain level for each channel
     int soft;                   // Enable/disable soft clipping
     int fast;                   // Use fix-point volume control
     float cfg_volume;
@@ -51,10 +51,10 @@ static int control(struct af_instance *af, int cmd, void *arg)
         }
         return af_test_output(af, (struct mp_audio *)arg);
     case AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_SET:
-        memcpy(s->level, arg, sizeof(float) * AF_NCH);
+        s->level = *(float *)arg;
         return AF_OK;
     case AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_GET:
-        memcpy(arg, s->level, sizeof(float) * AF_NCH);
+        *(float *)arg = s->level;
         return AF_OK;
     }
     return AF_UNKNOWN;
@@ -64,30 +64,25 @@ static struct mp_audio *play(struct af_instance *af, struct mp_audio *data)
 {
     struct mp_audio *c = data;
     struct priv *s = af->priv;
-    int nch = c->nch;
 
     if (af->data->format == AF_FORMAT_S16_NE) {
         int16_t *a = c->audio;
         int len = c->len / 2;
-        for (int ch = 0; ch < nch; ch++) {
-            int vol = 256.0 * s->level[ch];
-            if (vol != 256) {
-                for (int i = ch; i < len; i += nch) {
-                    int x = (a[i] * vol) >> 8;
-                    a[i] = MPCLAMP(x, SHRT_MIN, SHRT_MAX);
-                }
+        int vol = 256.0 * s->level;
+        if (vol != 256) {
+            for (int i = 0; i < len; i++) {
+                int x = (a[i] * vol) >> 8;
+                a[i] = MPCLAMP(x, SHRT_MIN, SHRT_MAX);
             }
         }
     } else if (af->data->format == AF_FORMAT_FLOAT_NE) {
         float *a = c->audio;
         int len = c->len / 4;
-        for (int ch = 0; ch < nch; ch++) {
-            if (s->level[ch] != 1.0) {
-                for (int i = ch; i < len; i += nch) {
-                    float x = a[i];
-                    x *= s->level[ch];
-                    a[i] = s->soft ? af_softclip(x) : MPCLAMP(x, -1.0, 1.0);
-                }
+        float vol = s->level;
+        if (vol != 1.0) {
+            for (int i = 0; i < len; i++) {
+                float x = a[i] * vol;
+                a[i] = s->soft ? af_softclip(x) : MPCLAMP(x, -1.0, 1.0);
             }
         }
     }
@@ -101,10 +96,7 @@ static int af_open(struct af_instance *af)
     af->play = play;
     af->mul = 1;
     af->data = talloc_zero(af, struct mp_audio);
-    float level;
-    af_from_dB(1, &s->cfg_volume, &level, 20.0, -200.0, 60.0);
-    for (int i = 0; i < AF_NCH; i++)
-        s->level[i] = level;
+    af_from_dB(1, &s->cfg_volume, &s->level, 20.0, -200.0, 60.0);
     return AF_OK;
 }
 
diff --git a/audio/mixer.c b/audio/mixer.c
index 4ecfe2bdf4..a58007c9dc 100644
--- a/audio/mixer.c
+++ b/audio/mixer.c
@@ -71,12 +71,12 @@ static void checkvolume(struct mixer *mixer)
 
     ao_control_vol_t vol = {mixer->vol_l, mixer->vol_r};
     if (mixer->softvol) {
-        float vals[AF_NCH];
+        float gain;
         if (!af_control_any_rev(mixer->af,
-                                AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_GET, vals))
-            vals[0] = vals[1] = 1.0;
-        vol.left = (vals[0] / (mixer->opts->softvol_max / 100.0)) * 100.0;
-        vol.right = (vals[1] / (mixer->opts->softvol_max / 100.0)) * 100.0;
+                                AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_GET, &gain))
+            gain = 1.0;
+        vol.left = (gain / (mixer->opts->softvol_max / 100.0)) * 100.0;
+        vol.right = (gain / (mixer->opts->softvol_max / 100.0)) * 100.0;
     } else {
         // Rely on the values not changing if the query is not supported
         ao_control(mixer->ao, AOCONTROL_GET_VOLUME, &vol);
@@ -118,20 +118,16 @@ static void setvolume_internal(struct mixer *mixer, float l, float r)
                     "[Mixer] Failed to change audio output volume.\n");
         return;
     }
-    float vals[AF_NCH];
-    vals[0] = l / 100.0 * mixer->opts->softvol_max / 100.0;
-    vals[1] = r / 100.0 * mixer->opts->softvol_max / 100.0;
-    for (int i = 2; i < AF_NCH; i++)
-        vals[i] = (vals[0] + vals[1]) / 2.0;
+    float gain = (l + r) / 2.0 / 100.0 * mixer->opts->softvol_max / 100.0;
     if (!af_control_any_rev(mixer->af,
                             AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_SET,
-                            vals))
+                            &gain))
     {
         mp_tmsg(MSGT_GLOBAL, MSGL_V, "[Mixer] Inserting volume filter.\n");
         if (!(af_add(mixer->af, "volume", NULL)
               && af_control_any_rev(mixer->af,
                                     AF_CONTROL_VOLUME_LEVEL | AF_CONTROL_SET,
-                                    vals)))
+                                    &gain)))
             mp_tmsg(MSGT_GLOBAL, MSGL_ERR,
                     "[Mixer] No volume control available.\n");
     }
-- 
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