Add a volume-adjust config option to adjust the source output volume

Designed for apps that either don't change the listener's AL_GAIN, or don't
allow the listener's AL_GAIN to go above 1. This allows the volume to still be
increased further than such apps may allow, if users find it too quiet.

Be aware that increasing this can easily cause clipping. The gain limit
reported by AL_GAIN_LIMIT_SOFT is also affected by this.

5 files changed, 32 insertions, 6 deletions

diff --git a/Alc/ALc.c b/Alc/ALc.c
index c4eb0462..a37e1242 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -2319,6 +2319,7 @@ static ALvoid InitContext(ALCcontext *Context)
     //Validate Context
     InitRef(&Context->UpdateCount, 0);
     ATOMIC_INIT(&Context->HoldUpdates, AL_FALSE);
+    Context->GainBoost = 1.0f;
     RWLockInit(&Context->PropLock);
     ATOMIC_INIT(&Context->LastError, AL_NO_ERROR);
     InitUIntMap(&Context->SourceMap, Context->Device->SourcesMax);
@@ -3159,6 +3160,7 @@ ALC_API ALCenum ALC_APIENTRY alcGetEnumValue(ALCdevice *device, const ALCchar *e
 ALC_API ALCcontext* ALC_APIENTRY alcCreateContext(ALCdevice *device, const ALCint *attrList)
 {
     ALCcontext *ALContext;
+    ALfloat valf;
     ALCenum err;
 
     LockLists();
@@ -3229,6 +3231,21 @@ ALC_API ALCcontext* ALC_APIENTRY alcCreateContext(ALCdevice *device, const ALCin
     ALCdevice_IncRef(device);
     InitContext(ALContext);
 
+    if(ConfigValueFloat(al_string_get_cstr(device->DeviceName), NULL, "volume-adjust", &valf))
+    {
+        if(!isfinite(valf))
+            ERR("volume-adjust must be finite: %f\n", valf);
+        else
+        {
+            ALfloat db = clampf(valf, -24.0f, 24.0f);
+            if(db != valf)
+                WARN("volume-adjust clamped: %f, range: +/-%f\n", valf, 24.0f);
+            ALContext->GainBoost = powf(10.0f, db/20.0f);
+            TRACE("volume-adjust gain: %f\n", ALContext->GainBoost);
+        }
+    }
+    UpdateListenerProps(ALContext);
+
     {
         ALCcontext *head = ATOMIC_LOAD(&device->ContextList);
         do {
diff --git a/Alc/ALu.c b/Alc/ALu.c
index f93781df..13aff5d9 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -278,7 +278,7 @@ static ALboolean CalcListenerParams(ALCcontext *Context)
                        0.0f);
     Listener->Params.Velocity = aluMatrixfVector(&Listener->Params.Matrix, &vel);
 
-    Listener->Params.Gain = ATOMIC_LOAD(&props->Gain, almemory_order_relaxed);
+    Listener->Params.Gain = ATOMIC_LOAD(&props->Gain, almemory_order_relaxed) * Context->GainBoost;
     Listener->Params.MetersPerUnit = ATOMIC_LOAD(&props->MetersPerUnit, almemory_order_relaxed);
 
     Listener->Params.DopplerFactor = ATOMIC_LOAD(&props->DopplerFactor, almemory_order_relaxed);
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 356a749a..6320bc98 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -749,6 +749,8 @@ struct ALCcontext_struct {
     RefCount UpdateCount;
     ATOMIC(ALenum) HoldUpdates;
 
+    ALfloat GainBoost;
+
     struct ALvoice *Voices;
     ALsizei VoiceCount;
     ALsizei MaxVoices;
diff --git a/OpenAL32/alState.c b/OpenAL32/alState.c
index c25aa63e..3d8e6c40 100644
--- a/OpenAL32/alState.c
+++ b/OpenAL32/alState.c
@@ -155,7 +155,7 @@ AL_API ALboolean AL_APIENTRY alGetBoolean(ALenum pname)
         break;
 
     case AL_GAIN_LIMIT_SOFT:
-        if(GAIN_MIX_MAX != 0.0f)
+        if(GAIN_MIX_MAX/context->GainBoost != 0.0f)
             value = AL_TRUE;
         break;
 
@@ -201,7 +201,7 @@ AL_API ALdouble AL_APIENTRY alGetDouble(ALenum pname)
         break;
 
     case AL_GAIN_LIMIT_SOFT:
-        value = (ALdouble)GAIN_MIX_MAX;
+        value = (ALdouble)GAIN_MIX_MAX/context->GainBoost;
         break;
 
     default:
@@ -246,7 +246,7 @@ AL_API ALfloat AL_APIENTRY alGetFloat(ALenum pname)
         break;
 
     case AL_GAIN_LIMIT_SOFT:
-        value = GAIN_MIX_MAX;
+        value = GAIN_MIX_MAX/context->GainBoost;
         break;
 
     default:
@@ -291,7 +291,7 @@ AL_API ALint AL_APIENTRY alGetInteger(ALenum pname)
         break;
 
     case AL_GAIN_LIMIT_SOFT:
-        value = (ALint)GAIN_MIX_MAX;
+        value = (ALint)(GAIN_MIX_MAX/context->GainBoost);
         break;
 
     default:
@@ -336,7 +336,7 @@ AL_API ALint64SOFT AL_APIENTRY alGetInteger64SOFT(ALenum pname)
         break;
 
     case AL_GAIN_LIMIT_SOFT:
-        value = (ALint64SOFT)GAIN_MIX_MAX;
+        value = (ALint64SOFT)(GAIN_MIX_MAX/context->GainBoost);
         break;
 
     default:
diff --git a/alsoftrc.sample b/alsoftrc.sample
index 444ebc6f..d5913ff0 100644
--- a/alsoftrc.sample
+++ b/alsoftrc.sample
@@ -182,6 +182,13 @@
 #  possible is 4.
 #sends =
 
+## volume-adjust:
+#  A global volume adjustment for source output, expressed in decibels. The
+#  value is logarithmic, so +6 will be a scale of (approximately) 2x, +12 will
+#  be a scale of 4x, etc. Similarly, -6 will be x1/2, and -12 is about x1/4. A
+#  value of 0 means no change.
+#volume-adjust = 0
+
 ## excludefx: (global)
 #  Sets which effects to exclude, preventing apps from using them. This can
 #  help for apps that try to use effects which are too CPU intensive for the