Scale the reverb decay weights to cover up to 20khz

Otherwise, using the device's maximum frequency will cause the weighting
factors to shift for different sample rates, irrespective of the content being
processed. 20khz is the maximum allowed reference frequency, and also acts as
the upper limit of human hearing.

1 files changed, 16 insertions, 11 deletions

diff --git a/Alc/effects/reverb.c b/Alc/effects/reverb.c
index 2c5205a1..f30956e5 100644
--- a/Alc/effects/reverb.c
+++ b/Alc/effects/reverb.c
@@ -980,8 +980,12 @@ static ALvoid UpdateEarlyLines(const ALfloat density, const ALfloat decayTime, c
 }
 
 /* Update the late reverb line lengths and T60 coefficients. */
-static ALvoid UpdateLateLines(const ALfloat density, const ALfloat diffusion, const ALfloat lfDecayTime, const ALfloat mfDecayTime, const ALfloat hfDecayTime, const ALfloat lfW, const ALfloat hfW, const ALfloat echoTime, const ALfloat echoDepth, const ALuint frequency, ALfloat *density_gain, LateReverb *Late)
+static ALvoid UpdateLateLines(const ALfloat density, const ALfloat diffusion, const ALfloat lfDecayTime, const ALfloat mfDecayTime, const ALfloat hfDecayTime, const ALfloat lf0norm, const ALfloat hf0norm, const ALfloat echoTime, const ALfloat echoDepth, const ALuint frequency, ALfloat *density_gain, LateReverb *Late)
 {
+    /* Scaling factor to convert the normalized reference frequencies from
+     * representing 0...freq to 0...max_reference.
+     */
+    const ALfloat norm_weight_factor = (ALfloat)frequency / AL_EAXREVERB_MAX_HFREFERENCE;
     ALfloat multiplier, length, bandWeights[3];
     ALsizei i;
 
@@ -1006,12 +1010,13 @@ static ALvoid UpdateLateLines(const ALfloat density, const ALfloat diffusion, co
      * losses of energy that reduce decay time due to scattering into highly
      * attenuated bands.
      */
-    bandWeights[0] = lfW;
-    bandWeights[1] = hfW - lfW;
-    bandWeights[2] = F_PI - hfW;
+    bandWeights[0] = lf0norm*norm_weight_factor;
+    bandWeights[1] = hf0norm*norm_weight_factor - lf0norm*norm_weight_factor;
+    bandWeights[2] = 1.0f - hf0norm*norm_weight_factor;
     *density_gain = CalcDensityGain(
-        CalcDecayCoeff(length, (bandWeights[0]*lfDecayTime + bandWeights[1]*mfDecayTime +
-                                bandWeights[2]*hfDecayTime) / F_PI)
+        CalcDecayCoeff(length,
+            bandWeights[0]*lfDecayTime + bandWeights[1]*mfDecayTime + bandWeights[2]*hfDecayTime
+        )
     );
 
     for(i = 0;i < NUM_LINES;i++)
@@ -1043,7 +1048,7 @@ static ALvoid UpdateLateLines(const ALfloat density, const ALfloat diffusion, co
 
         /* Calculate the T60 damping coefficients for each line. */
         CalcT60DampingCoeffs(length, lfDecayTime, mfDecayTime, hfDecayTime,
-                             lfW, hfW, Late->T60[i].LFCoeffs,
+                             lf0norm*F_TAU, hf0norm*F_TAU, Late->T60[i].LFCoeffs,
                              Late->T60[i].HFCoeffs);
     }
 }
@@ -1195,10 +1200,10 @@ static ALvoid ALreverbState_update(ALreverbState *State, const ALCcontext *Conte
 
     /* Update the late lines. */
     UpdateLateLines(props->Reverb.Density, props->Reverb.Diffusion,
-                    lfDecayTime, props->Reverb.DecayTime, hfDecayTime,
-                    F_TAU * lf0norm, F_TAU * hf0norm,
-                    props->Reverb.EchoTime, props->Reverb.EchoDepth,
-                    frequency, &density_gain, &State->Late);
+        lfDecayTime, props->Reverb.DecayTime, hfDecayTime, lf0norm, hf0norm,
+        props->Reverb.EchoTime, props->Reverb.EchoDepth, frequency, &density_gain,
+        &State->Late
+    );
 
     /* Update early and late 3D panning. */
     gain = props->Reverb.Gain * Slot->Params.Gain * ReverbBoost;