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Use a separate unmodulated feedback tap for reverb

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This commit is contained in:
Chris Robinson 2017-12-24 14:21:13 -08:00
parent 3633b65e04
commit b32a366137
1 changed files with 20 additions and 18 deletions
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38
Alc/effects/reverb.c
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@ -220,11 +220,11 @@ static const ALfloat LATE_LINE_LENGTHS[4] =
}; };
/* This coefficient is used to define the delay scale from the sinus, according /* This coefficient is used to define the delay scale from the sinus, according
* to the modulation depth property. This value must be below half the shortest * to the modulation depth property. This value must be below the shortest late
* late line length (0.0097/2 = ~0.0048), otherwise with certain parameters * line length (0.0097), otherwise with certain parameters (high mod time, low
* (high mod time, low density) the downswing can sample before the input. * density) the downswing can sample before the input.
*/ */
static const ALfloat MODULATION_DEPTH_COEFF = 1.0f / 4096.0f; static const ALfloat MODULATION_DEPTH_COEFF = 0.0032f;
/* A filter is used to avoid the terrible distortion caused by changing /* A filter is used to avoid the terrible distortion caused by changing
* modulation time and/or depth. To be consistent across different sample * modulation time and/or depth. To be consistent across different sample
@ -1055,22 +1055,21 @@ static ALvoid UpdateModulator(const ALfloat modTime, const ALfloat modDepth,
* (1 sample) and when the timing changes, the index is rescaled to the new * (1 sample) and when the timing changes, the index is rescaled to the new
* range to keep the sinus consistent. * range to keep the sinus consistent.
*/ */
range = maxi(fastf2i(modTime*frequency), 1); range = fastf2i(modTime*frequency + 0.5f);
State->Mod.Index = (ALsizei)(State->Mod.Index * (ALint64)range / State->Mod.Index = (ALsizei)(State->Mod.Index * (ALint64)range /
State->Mod.Range) % range; State->Mod.Range) % range;
State->Mod.Range = range; State->Mod.Range = range;
State->Mod.Scale = F_TAU / range; State->Mod.Scale = F_TAU / range;
/* The modulation depth effects the scale of the sinus, which changes how /* The modulation depth effects the scale of the sinus, which varies the
* much extra delay is added to the delay line. This delay changing over * delay for the tapped output. This delay changing over time changes the
* time changes the pitch, creating the modulation effect. The scale needs * pitch, creating the modulation effect. The scale needs to be multiplied
* to be multiplied by the modulation time so that a given depth produces a * by the modulation time (itself scaled by the max modulation time) so
* consistent shift in frequency over all ranges of time. Since the depth * that a given depth produces a consistent shift in frequency over all
* is applied to a sinus value, it needs to be halved for the sinus swing * ranges of time.
* in time (half of it is spent decreasing the frequency, half is spent
* increasing it).
*/ */
State->Mod.Depth = modDepth * MODULATION_DEPTH_COEFF * modTime / 2.0f * State->Mod.Depth = modDepth * MODULATION_DEPTH_COEFF *
(modTime / AL_EAXREVERB_MAX_MODULATION_TIME) *
frequency; frequency;
} }
@ -1706,20 +1705,23 @@ static ALvoid LateReverb_##T(ALreverbState *State, const ALsizei todo, \
\ \
delay = offset - moddelay[i]; \ delay = offset - moddelay[i]; \
for(j = 0;j < 4;j++) \ for(j = 0;j < 4;j++) \
f[j] += DELAY_OUT_##T(&State->Late.Delay, \ out[j][i] = f[j] + DELAY_OUT_##T(&State->Late.Delay, \
delay-State->Late.Offset[j][0], \ delay-State->Late.Offset[j][0], \
delay-State->Late.Offset[j][1], j, fade \ delay-State->Late.Offset[j][1], j, fade \
); \ ); \
\ \
for(j = 0;j < 4;j++) \
f[j] += DELAY_OUT_##T(&State->Late.Delay, \
offset-State->Late.Offset[j][0], \
offset-State->Late.Offset[j][1], j, fade \
); \
\
for(j = 0;j < 4;j++) \ for(j = 0;j < 4;j++) \
f[j] = LateT60Filter(j, f[j], State); \ f[j] = LateT60Filter(j, f[j], State); \
\ \
VectorAllpass_##T(f, offset, apFeedCoeff, mixX, mixY, fade, \ VectorAllpass_##T(f, offset, apFeedCoeff, mixX, mixY, fade, \
&State->Late.VecAp); \ &State->Late.VecAp); \
\ \
for(j = 0;j < 4;j++) \
out[j][i] = f[j]; \
\
VectorReverse(f); \ VectorReverse(f); \
\ \
VectorPartialScatter(f, mixX, mixY); \ VectorPartialScatter(f, mixX, mixY); \