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Experimental attenuation curve: linear falloff, with prescribed propagation limit.

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A positive coefficient sets logarithmic falloff, as before.
A negative coefficient sets linear falloff, where abs(coefficient) is the distance limit in meters.
This commit is contained in:
Ken Cooke 2019-01-17 13:59:33 -08:00
parent 7cade1e354
commit 3ffaced0f3
2 changed files with 23 additions and 9 deletions
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2
assignment-client/src/audio/AudioMixer.cpp
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@ -736,7 +736,7 @@ void AudioMixer::parseSettingsObject(const QJsonObject& settingsObject) {
float coefficient = coefficientObject.value(COEFFICIENT).toString().toFloat(&ok); float coefficient = coefficientObject.value(COEFFICIENT).toString().toFloat(&ok);
if (ok && coefficient >= 0.0f && coefficient <= 1.0f && if (ok && coefficient <= 1.0f &&
itSource != end(_audioZones) && itSource != end(_audioZones) &&
itListener != end(_audioZones)) { itListener != end(_audioZones)) {

18
assignment-client/src/audio/AudioMixerSlave.cpp
View file

@ -770,15 +770,29 @@ float computeGain(float masterListenerGain, const AvatarAudioStream& listeningNo
break; break;
} }
} }
// translate the zone setting to gain per log2(distance)
if (attenuationPerDoublingInDistance < 0.0f) {
// translate a negative zone setting to distance limit
const float MIN_DISTANCE_LIMIT = ATTN_DISTANCE_REF + 1.0f; // silent after 1m
float distanceLimit = std::max(-attenuationPerDoublingInDistance, MIN_DISTANCE_LIMIT);
// calculate the LINEAR attenuation using the distance to this node
// reference attenuation of 0dB at distance = ATTN_DISTANCE_REF
float d = distance - ATTN_DISTANCE_REF;
gain *= std::max(1.0f - d / (distanceLimit - ATTN_DISTANCE_REF), 0.0f);
gain = std::min(gain, ATTN_GAIN_MAX);
} else {
// translate a positive zone setting to gain per log2(distance)
const float MIN_ATTENUATION_COEFFICIENT = 0.001f; // -60dB per log2(distance) const float MIN_ATTENUATION_COEFFICIENT = 0.001f; // -60dB per log2(distance)
float g = glm::clamp(1.0f - attenuationPerDoublingInDistance, MIN_ATTENUATION_COEFFICIENT, 1.0f); float g = glm::clamp(1.0f - attenuationPerDoublingInDistance, MIN_ATTENUATION_COEFFICIENT, 1.0f);
// calculate the attenuation using the distance to this node // calculate the LOGARITHMIC attenuation using the distance to this node
// reference attenuation of 0dB at distance = ATTN_DISTANCE_REF // reference attenuation of 0dB at distance = ATTN_DISTANCE_REF
float d = (1.0f / ATTN_DISTANCE_REF) * std::max(distance, HRTF_NEARFIELD_MIN); float d = (1.0f / ATTN_DISTANCE_REF) * std::max(distance, HRTF_NEARFIELD_MIN);
gain *= fastExp2f(fastLog2f(g) * fastLog2f(d)); gain *= fastExp2f(fastLog2f(g) * fastLog2f(d));
gain = std::min(gain, ATTN_GAIN_MAX); gain = std::min(gain, ATTN_GAIN_MAX);
}
return gain; return gain;
} }