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.

1 files changed, 17 insertions, 0 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 {