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Include the average modulation delay for the late reverb feedback

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This commit is contained in:
Chris Robinson 2020-04-06 15:46:14 -07:00
parent baf14aad2a
commit 6ff5339112
1 changed files with 63 additions and 59 deletions
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122
alc/effects/reverb.cpp
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@ -336,8 +336,7 @@ struct Modulation {
/* The vibrato time is tracked with an index over a (MOD_FRACONE)
* normalized range.
*/
ALuint Index[NUM_LINES];
ALuint Step;
ALuint Index, Step;
/* The depth of frequency change, in samples. */
float Depth[2];
@ -346,8 +345,8 @@ struct Modulation {
void updateModulator(float modTime, float modDepth, float frequency);
void calcDelays(size_t c, size_t todo);
void calcFadedDelays(size_t c, size_t todo, float fadeCount, float fadeStep);
void calcDelays(size_t todo);
void calcFadedDelays(size_t todo, float fadeCount, float fadeStep);
};
struct LateReverb {
@ -643,7 +642,7 @@ bool ReverbState::deviceUpdate(const ALCdevice *device)
t60.LFFilter.clear();
}
std::fill(std::begin(mLate.Mod.Index), std::end(mLate.Mod.Index), 0);
mLate.Mod.Index = 0;
mLate.Mod.Step = 1;
std::fill(std::begin(mLate.Mod.Depth), std::end(mLate.Mod.Depth), 0.0f);
@ -793,6 +792,39 @@ void EarlyReflections::updateLines(const ALfloat density, const ALfloat diffusio
}
}
/* Update the EAX modulation step and depth. Keep in mind that this kind of
* vibrato is additive and not multiplicative as one may expect. The downswing
* will sound stronger than the upswing.
*/
void Modulation::updateModulator(float modTime, float modDepth, float frequency)
{
/* Modulation is calculated in two parts.
*
* The modulation time effects the sinus rate, altering the speed of
* frequency changes. An index is incremented for each sample with an
* appropriate step size to generate an LFO, which will vary the feedback
* delay over time.
*/
Step = maxu(fastf2u(MOD_FRACONE / (frequency * modTime)), 1);
/* The modulation depth effects the amount of frequency change over the
* range of the sinus. It needs to be scaled by the modulation time so that
* a given depth produces a consistent change in frequency over all ranges
* of time. Since the depth is applied to a sinus value, it needs to be
* halved once for the sinus range and again for the sinus swing in time
* (half of it is spent decreasing the frequency, half is spent increasing
* it).
*/
Depth[1] = modDepth * MODULATION_DEPTH_COEFF * modTime * frequency / 4.0f;
/* To cancel the effects of a long period modulation on the reverberation,
* the amount of pitch should be varied (decreased) according to the
* modulation time. The natural form is varying inversely, in fact
* resulting in an invariant over the previous expression.
*/
Depth[1] *= minf(AL_EAXREVERB_DEFAULT_MODULATION_TIME / modTime, 1.0f);
}
/* Update the late reverb line lengths and T60 coefficients. */
void LateReverb::updateLines(const ALfloat density, const ALfloat diffusion,
const ALfloat lfDecayTime, const ALfloat mfDecayTime, const ALfloat hfDecayTime,
@ -848,9 +880,11 @@ void LateReverb::updateLines(const ALfloat density, const ALfloat diffusion,
/* Approximate the absorption that the vector all-pass would exhibit
* given the current diffusion so we don't have to process a full T60
* filter for each of its four lines.
* filter for each of its four lines. Also include the average
* modulation delay (depth is half the max delay in samples).
*/
length += lerp(LATE_ALLPASS_LENGTHS[i], late_allpass_avg, diffusion) * multiplier;
length += lerp(LATE_ALLPASS_LENGTHS[i], late_allpass_avg, diffusion)*multiplier +
Mod.Depth[1]/frequency;
/* Calculate the T60 damping coefficients for each line. */
T60[i].calcCoeffs(length, lfDecayTime, mfDecayTime, hfDecayTime, lf0norm, hf0norm);
@ -888,39 +922,6 @@ void ReverbState::updateDelayLine(const ALfloat earlyDelay, const ALfloat lateDe
}
}
/* Update the EAX modulation step and depth. Keep in mind that this kind of
* vibrato is additive and not multiplicative as one may expect. The downswing
* will sound stronger than the upswing.
*/
void Modulation::updateModulator(float modTime, float modDepth, float frequency)
{
/* Modulation is calculated in two parts.
*
* The modulation time effects the sinus rate, altering the speed of
* frequency changes. An index is incremented for each sample with an
* appropriate step size to generate an LFO, which will vary the feedback
* delay over time.
*/
Step = maxu(fastf2u(MOD_FRACONE / (frequency * modTime)), 1);
/* The modulation depth effects the amount of frequency change over the
* range of the sinus. It needs to be scaled by the modulation time so that
* a given depth produces a consistent change in frequency over all ranges
* of time. Since the depth is applied to a sinus value, it needs to be
* halved once for the sinus range and again for the sinus swing in time
* (half of it is spent decreasing the frequency, half is spent increasing
* it).
*/
Depth[1] = modDepth * MODULATION_DEPTH_COEFF * modTime * frequency / 4.0f;
/* To cancel the effects of a long period modulation on the reverberation,
* the amount of pitch should be varied (decreased) according to the
* modulation time. The natural form is varying inversely, in fact
* resulting in an invariant over the previous expression.
*/
Depth[1] *= minf(AL_EAXREVERB_DEFAULT_MODULATION_TIME / modTime, 1.0f);
}
/* Creates a transform matrix given a reverb vector. The vector pans the reverb
* reflections toward the given direction, using its magnitude (up to 1) as a
* focal strength. This function results in a B-Format transformation matrix
@ -1031,14 +1032,14 @@ void ReverbState::update(const ALCcontext *Context, const ALeffectslot *Slot, co
const ALfloat hfDecayTime{clampf(props->Reverb.DecayTime * hfRatio,
AL_EAXREVERB_MIN_DECAY_TIME, AL_EAXREVERB_MAX_DECAY_TIME)};
/* Update the modulator rate and depth. */
mLate.Mod.updateModulator(props->Reverb.ModulationTime, props->Reverb.ModulationDepth,
frequency);
/* Update the late lines. */
mLate.updateLines(props->Reverb.Density, props->Reverb.Diffusion, lfDecayTime,
props->Reverb.DecayTime, hfDecayTime, lf0norm, hf0norm, frequency);
/* Update the modulator line. */
mLate.Mod.updateModulator(props->Reverb.ModulationTime, props->Reverb.ModulationDepth,
frequency);
/* Update early and late 3D panning. */
const ALfloat gain{props->Reverb.Gain * Slot->Params.Gain * ReverbBoost};
update3DPanning(props->Reverb.ReflectionsPan, props->Reverb.LateReverbPan,
@ -1408,23 +1409,25 @@ void ReverbState::earlyFaded(const size_t offset, const size_t todo, const ALflo
}
void Modulation::calcDelays(size_t c, size_t todo)
void Modulation::calcDelays(size_t todo)
{
ALuint idx{Index[c]};
constexpr float inv_scale{MOD_FRACONE / al::MathDefs<float>::Tau()};
ALuint idx{Index};
const ALuint step{Step};
const float depth{Depth[0]};
for(size_t i{0};i < todo;++i)
{
idx += step;
ModDelays[i] = (std::sin(static_cast<float>(idx & MOD_FRACMASK) /
(MOD_FRACONE / al::MathDefs<float>::Tau())) + 1.0f) * depth;
const float lfo{std::sin(static_cast<float>(idx&MOD_FRACMASK) / inv_scale)};
ModDelays[i] = (lfo+1.0f) * depth;
}
Index[c] = idx;
Index = idx;
}
void Modulation::calcFadedDelays(size_t c, size_t todo, float fadeCount, float fadeStep)
void Modulation::calcFadedDelays(size_t todo, float fadeCount, float fadeStep)
{
ALuint idx{Index[c]};
constexpr float inv_scale{MOD_FRACONE / al::MathDefs<float>::Tau()};
ALuint idx{Index};
const ALuint step{Step};
const float depth{Depth[0]};
const float depthStep{(Depth[1]-depth) * fadeStep};
@ -1432,10 +1435,10 @@ void Modulation::calcFadedDelays(size_t c, size_t todo, float fadeCount, float f
{
fadeCount += 1.0f;
idx += step;
ModDelays[i] = (std::sin(static_cast<float>(idx & MOD_FRACMASK) /
(MOD_FRACONE / al::MathDefs<float>::Tau())) + 1.0f) * (depth + depthStep*fadeCount);
const float lfo{std::sin(static_cast<float>(idx&MOD_FRACMASK) / inv_scale)};
ModDelays[i] = (lfo+1.0f) * (depth + depthStep*fadeCount);
}
Index[c] = idx;
Index = idx;
}
@ -1462,13 +1465,14 @@ void ReverbState::lateUnfaded(const size_t offset, const size_t todo)
ASSUME(todo > 0);
/* First, load decorrelated samples from the main and feedback delay lines.
/* First, calculate the modulated delays for the late feedback. */
mLate.Mod.calcDelays(todo);
/* Next, load decorrelated samples from the main and feedback delay lines.
* Filter the signal to apply its frequency-dependent decay.
*/
for(size_t j{0u};j < NUM_LINES;j++)
{
mLate.Mod.calcDelays(j, todo);
const DelayLineI mod_delay{mLate.Mod.Delay};
size_t late_delay_tap{offset - mLateDelayTap[j][0]};
size_t late_feedb_tap{offset - mLate.Offset[j][0]};
@ -1529,10 +1533,10 @@ void ReverbState::lateFaded(const size_t offset, const size_t todo, const ALfloa
ASSUME(todo > 0);
mLate.Mod.calcFadedDelays(todo, fade, fadeStep);
for(size_t j{0u};j < NUM_LINES;j++)
{
mLate.Mod.calcFadedDelays(j, todo, fade, fadeStep);
const DelayLineI mod_delay{mLate.Mod.Delay};
const ALfloat oldMidGain{mLate.T60[j].MidGain[0]};
const ALfloat midGain{mLate.T60[j].MidGain[1]};