mirror of
https://github.com/lubosz/overte.git
synced 2025-04-10 17:22:40 +02:00
Brad Hefta-Gaub
GitHub
commit
878a01cbaf
5 changed files with 390 additions and 104 deletions
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@ -193,8 +193,12 @@ void AudioMixer::addStreamToMixForListeningNodeWithStream(AudioMixerClientData&
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// check if this is a server echo of a source back to itself
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bool isEcho = (&streamToAdd == &listeningNodeStream);
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// figure out the gain for this source at the listener
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glm::vec3 relativePosition = streamToAdd.getPosition() - listeningNodeStream.getPosition();
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// figure out the distance between source and listener
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float distance = glm::max(glm::length(relativePosition), EPSILON);
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// figure out the gain for this source at the listener
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float gain = gainForSource(streamToAdd, listeningNodeStream, relativePosition, isEcho);
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// figure out the azimuth to this source at the listener
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@ -240,7 +244,7 @@ void AudioMixer::addStreamToMixForListeningNodeWithStream(AudioMixerClientData&
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// this is not done for stereo streams since they do not go through the HRTF
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static int16_t silentMonoBlock[AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL] = {};
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hrtf.renderSilent(silentMonoBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, gain,
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hrtf.renderSilent(silentMonoBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, distance, gain,
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AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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++_hrtfSilentRenders;;
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@ -287,7 +291,7 @@ void AudioMixer::addStreamToMixForListeningNodeWithStream(AudioMixerClientData&
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// silent frame from source
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// we still need to call renderSilent via the HRTF for mono source
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hrtf.renderSilent(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, gain,
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hrtf.renderSilent(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, distance, gain,
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AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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++_hrtfSilentRenders;
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@ -300,7 +304,7 @@ void AudioMixer::addStreamToMixForListeningNodeWithStream(AudioMixerClientData&
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// the mixer is struggling so we're going to drop off some streams
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// we call renderSilent via the HRTF with the actual frame data and a gain of 0.0
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hrtf.renderSilent(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, 0.0f,
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hrtf.renderSilent(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, distance, 0.0f,
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AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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++_hrtfStruggleRenders;
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@ -311,7 +315,7 @@ void AudioMixer::addStreamToMixForListeningNodeWithStream(AudioMixerClientData&
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++_hrtfRenders;
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// mono stream, call the HRTF with our block and calculated azimuth and gain
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hrtf.render(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, gain,
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hrtf.render(streamBlock, _mixedSamples, HRTF_DATASET_INDEX, azimuth, distance, gain,
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AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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}
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@ -882,13 +882,13 @@ void AudioClient::mixLocalAudioInjectors(int16_t* inputBuffer) {
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} else {
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// calculate gain and azimuth for hrtf
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// calculate distance, gain and azimuth for hrtf
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glm::vec3 relativePosition = injector->getPosition() - _positionGetter();
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float gain = gainForSource(relativePosition, injector->getVolume());
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float azimuth = azimuthForSource(relativePosition);
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float distance = glm::max(glm::length(relativePosition), EPSILON);
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float gain = gainForSource(distance, injector->getVolume());
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float azimuth = azimuthForSource(relativePosition);
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injector->getLocalHRTF().render(_scratchBuffer, _hrtfBuffer, 1, azimuth, gain, AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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injector->getLocalHRTF().render(_scratchBuffer, _hrtfBuffer, 1, azimuth, distance, gain, AudioConstants::NETWORK_FRAME_SAMPLES_PER_CHANNEL);
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}
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} else {
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@ -1298,37 +1298,19 @@ float AudioClient::azimuthForSource(const glm::vec3& relativePosition) {
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}
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}
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float AudioClient::gainForSource(const glm::vec3& relativePosition, float volume) {
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// TODO: put these in a place where we can share with AudioMixer!
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const float DEFAULT_ATTENUATION_PER_DOUBLING_IN_DISTANCE = 0.18f;
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float AudioClient::gainForSource(float distance, float volume) {
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const float ATTENUATION_BEGINS_AT_DISTANCE = 1.0f;
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//qDebug() << "initial gain is " << volume;
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// I'm assuming that the AudioMixer's getting of the stream's attenuation
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// factor is basically same as getting volume
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float gain = volume;
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float distanceBetween = glm::length(relativePosition);
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if (distanceBetween < EPSILON ) {
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distanceBetween = EPSILON;
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// attenuate based on distance
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if (distance >= ATTENUATION_BEGINS_AT_DISTANCE) {
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gain /= distance; // attenuation = -6dB * log2(distance)
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}
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// audio mixer has notion of zones. Unsure how to map that across here...
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// attenuate based on distance now
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if (distanceBetween >= ATTENUATION_BEGINS_AT_DISTANCE) {
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float distanceCoefficient = 1.0f - (logf(distanceBetween/ATTENUATION_BEGINS_AT_DISTANCE) / logf(2.0f)
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* DEFAULT_ATTENUATION_PER_DOUBLING_IN_DISTANCE);
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if (distanceCoefficient < 0.0f) {
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distanceCoefficient = 0.0f;
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}
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gain *= distanceCoefficient;
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}
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//qDebug() << "calculated gain as " << gain;
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return gain;
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}
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@ -217,7 +217,7 @@ private:
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void outputFormatChanged();
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void mixLocalAudioInjectors(int16_t* inputBuffer);
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float azimuthForSource(const glm::vec3& relativePosition);
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float gainForSource(const glm::vec3& relativePosition, float volume);
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float gainForSource(float distance, float volume);
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QByteArray firstInputFrame;
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QAudioInput* _audioInput;
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@ -16,6 +16,13 @@
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#include "AudioHRTF.h"
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#include "AudioHRTFData.h"
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#ifndef MAX
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#define MAX(a,b) (((a) > (b)) ? (a) : (b))
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#endif
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#ifndef MIN
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#define MIN(a,b) (((a) < (b)) ? (a) : (b))
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#endif
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//
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// Equal-gain crossfade
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//
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@ -58,6 +65,103 @@ static const float crossfadeTable[HRTF_BLOCK] = {
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0.0024846123f, 0.0019026510f, 0.0013981014f, 0.0009710421f, 0.0006215394f, 0.0003496476f, 0.0001554090f, 0.0000388538f,
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};
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//
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// Model the frequency-dependent attenuation of sound propogation in air.
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//
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// Fit using linear regression to a log-log model of lowpass cutoff frequency vs distance,
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// loosely based on data from Handbook of Acoustics. Only the onset of significant
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// attenuation is modelled, not the filter slope.
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//
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// 1m -> -3dB @ 55kHz
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// 10m -> -3dB @ 12kHz
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// 100m -> -3dB @ 2.5kHz
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// 1km -> -3dB @ 0.6kHz
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// 10km -> -3dB @ 0.1kHz
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//
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static const int NLOWPASS = 64;
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static const float lowpassTable[NLOWPASS][5] = { // { b0, b1, b2, a1, a2 }
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// distance = 1
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{ 0.999772371f, 1.399489756f, 0.454495527f, 1.399458985f, 0.454298669f },
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{ 0.999631480f, 1.357609808f, 0.425210203f, 1.357549905f, 0.424901586f },
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{ 0.999405154f, 1.311503050f, 0.394349994f, 1.311386830f, 0.393871368f },
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{ 0.999042876f, 1.260674595f, 0.361869089f, 1.260450057f, 0.361136504f },
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// distance = 2
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{ 0.998465222f, 1.204646525f, 0.327757118f, 1.204214978f, 0.326653886f },
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{ 0.997548106f, 1.143019308f, 0.292064663f, 1.142195387f, 0.290436690f },
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{ 0.996099269f, 1.075569152f, 0.254941286f, 1.074009405f, 0.252600301f },
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{ 0.993824292f, 1.002389610f, 0.216688640f, 0.999469185f, 0.213433357f },
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// distance = 4
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{ 0.990280170f, 0.924075266f, 0.177827150f, 0.918684864f, 0.173497723f },
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{ 0.984818279f, 0.841917936f, 0.139164195f, 0.832151968f, 0.133748443f },
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{ 0.976528670f, 0.758036513f, 0.101832398f, 0.740761682f, 0.095635899f },
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{ 0.964216485f, 0.675305244f, 0.067243474f, 0.645654855f, 0.061110348f },
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// distance = 8
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{ 0.946463038f, 0.596943020f, 0.036899688f, 0.547879974f, 0.032425772f },
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{ 0.921823868f, 0.525770189f, 0.012060451f, 0.447952111f, 0.011702396f },
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{ 0.890470015f, 0.463334299f, -0.001227816f, 0.347276405f, 0.005300092f },
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{ 0.851335343f, 0.407521164f, -0.009353968f, 0.241900234f, 0.007602305f },
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// distance = 16
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{ 0.804237360f, 0.358139558f, -0.014293332f, 0.130934213f, 0.017149373f },
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{ 0.750073259f, 0.314581568f, -0.016625381f, 0.014505388f, 0.033524057f },
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{ 0.690412072f, 0.275936128f, -0.017054561f, -0.106682490f, 0.055976129f },
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{ 0.627245545f, 0.241342015f, -0.016246850f, -0.231302564f, 0.083643275f },
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// distance = 32
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{ 0.562700627f, 0.210158533f, -0.014740899f, -0.357562697f, 0.115680957f },
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{ 0.498787849f, 0.181982455f, -0.012925406f, -0.483461730f, 0.151306628f },
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{ 0.437224055f, 0.156585449f, -0.011055180f, -0.607042210f, 0.189796534f },
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{ 0.379336998f, 0.133834032f, -0.009281617f, -0.726580065f, 0.230469477f },
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// distance = 64
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{ 0.326040627f, 0.113624970f, -0.007683443f, -0.840693542f, 0.272675696f },
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{ 0.277861727f, 0.095845793f, -0.006291936f, -0.948380091f, 0.315795676f },
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{ 0.234997480f, 0.080357656f, -0.005109519f, -1.049001190f, 0.359246807f },
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{ 0.197386484f, 0.066993521f, -0.004122547f, -1.142236313f, 0.402493771f },
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// distance = 128
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{ 0.164780457f, 0.055564709f, -0.003309645f, -1.228023442f, 0.445058962f },
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{ 0.136808677f, 0.045870650f, -0.002646850f, -1.306498037f, 0.486530514f },
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{ 0.113031290f, 0.037708627f, -0.002110591f, -1.377937457f, 0.526566783f },
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{ 0.092980475f, 0.030881892f, -0.001679255f, -1.442713983f, 0.564897095f },
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// distance = 256
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{ 0.076190239f, 0.025205585f, -0.001333863f, -1.501257246f, 0.601319206f },
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{ 0.062216509f, 0.020510496f, -0.001058229f, -1.554025452f, 0.635694228f },
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{ 0.050649464f, 0.016644994f, -0.000838826f, -1.601484205f, 0.667939837f },
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{ 0.041120009f, 0.013475547f, -0.000664513f, -1.644091518f, 0.698022561f },
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// distance = 512
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{ 0.033302044f, 0.010886252f, -0.000526217f, -1.682287704f, 0.725949783f },
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{ 0.026911868f, 0.008777712f, -0.000416605f, -1.716488979f, 0.751761953f },
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{ 0.021705773f, 0.007065551f, -0.000329788f, -1.747083800f, 0.775525335f },
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{ 0.017476603f, 0.005678758f, -0.000261057f, -1.774431204f, 0.797325509f },
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// distance = 1024
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{ 0.014049828f, 0.004558012f, -0.000206658f, -1.798860530f, 0.817261711f },
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{ 0.011279504f, 0.003654067f, -0.000163610f, -1.820672082f, 0.835442043f },
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{ 0.009044384f, 0.002926264f, -0.000129544f, -1.840138412f, 0.851979516f },
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{ 0.007244289f, 0.002341194f, -0.000102586f, -1.857505967f, 0.866988864f },
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// distance = 2048
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{ 0.005796846f, 0.001871515f, -0.000081250f, -1.872996926f, 0.880584038f },
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{ 0.004634607f, 0.001494933f, -0.000064362f, -1.886811124f, 0.892876302f },
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{ 0.003702543f, 0.001193324f, -0.000050993f, -1.899127955f, 0.903972829f },
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{ 0.002955900f, 0.000951996f, -0.000040407f, -1.910108223f, 0.913975712f },
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// distance = 4096
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{ 0.002358382f, 0.000759068f, -0.000032024f, -1.919895894f, 0.922981321f },
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{ 0.001880626f, 0.000604950f, -0.000025383f, -1.928619738f, 0.931079931f },
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{ 0.001498926f, 0.000481920f, -0.000020123f, -1.936394836f, 0.938355560f },
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{ 0.001194182f, 0.000383767f, -0.000015954f, -1.943323983f, 0.944885977f },
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// distance = 8192
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{ 0.000951028f, 0.000305502f, -0.000012651f, -1.949498943f, 0.950742822f },
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{ 0.000757125f, 0.000243126f, -0.000010033f, -1.955001608f, 0.955991826f },
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{ 0.000602572f, 0.000193434f, -0.000007957f, -1.959905036f, 0.960693085f },
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{ 0.000479438f, 0.000153861f, -0.000006312f, -1.964274383f, 0.964901371f },
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// distance = 16384
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{ 0.000381374f, 0.000122359f, -0.000005007f, -1.968167752f, 0.968666478f },
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{ 0.000303302f, 0.000097288f, -0.000003972f, -1.971636944f, 0.972033562f },
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{ 0.000241166f, 0.000077342f, -0.000003151f, -1.974728138f, 0.975043493f },
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{ 0.000191726f, 0.000061475f, -0.000002500f, -1.977482493f, 0.977733194f },
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// distance = 32768
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{ 0.000152399f, 0.000048857f, -0.000001984f, -1.979936697f, 0.980135969f },
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{ 0.000121122f, 0.000038825f, -0.000001574f, -1.982123446f, 0.982281818f },
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{ 0.000096252f, 0.000030849f, -0.000001249f, -1.984071877f, 0.984197728f },
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{ 0.000076480f, 0.000024509f, -0.000000991f, -1.985807957f, 0.985907955f },
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};
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static const float TWOPI = 6.283185307f;
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//
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@ -162,40 +266,68 @@ static void interleave_4x4(float* src0, float* src1, float* src2, float* src3, f
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}
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}
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// 4 channels (interleaved)
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static void biquad_4x4(float* src, float* dst, float coef[5][4], float state[2][4], int numFrames) {
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// process 2 cascaded biquads on 4 channels (interleaved)
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// biquads computed in parallel, by adding one sample of delay
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static void biquad2_4x4(float* src, float* dst, float coef[5][8], float state[3][8], int numFrames) {
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// enable flush-to-zero mode to prevent denormals
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unsigned int ftz = _MM_GET_FLUSH_ZERO_MODE();
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_MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
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__m128 w1 = _mm_loadu_ps(state[0]);
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__m128 w2 = _mm_loadu_ps(state[1]);
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// restore state
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__m128 y00 = _mm_loadu_ps(&state[0][0]);
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__m128 w10 = _mm_loadu_ps(&state[1][0]);
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__m128 w20 = _mm_loadu_ps(&state[2][0]);
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__m128 b0 = _mm_loadu_ps(coef[0]);
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__m128 b1 = _mm_loadu_ps(coef[1]);
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__m128 b2 = _mm_loadu_ps(coef[2]);
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__m128 a1 = _mm_loadu_ps(coef[3]);
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__m128 a2 = _mm_loadu_ps(coef[4]);
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__m128 y01;
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__m128 w11 = _mm_loadu_ps(&state[1][4]);
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__m128 w21 = _mm_loadu_ps(&state[2][4]);
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// first biquad coefs
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__m128 b00 = _mm_loadu_ps(&coef[0][0]);
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__m128 b10 = _mm_loadu_ps(&coef[1][0]);
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__m128 b20 = _mm_loadu_ps(&coef[2][0]);
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__m128 a10 = _mm_loadu_ps(&coef[3][0]);
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__m128 a20 = _mm_loadu_ps(&coef[4][0]);
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// second biquad coefs
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__m128 b01 = _mm_loadu_ps(&coef[0][4]);
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__m128 b11 = _mm_loadu_ps(&coef[1][4]);
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__m128 b21 = _mm_loadu_ps(&coef[2][4]);
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__m128 a11 = _mm_loadu_ps(&coef[3][4]);
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__m128 a21 = _mm_loadu_ps(&coef[4][4]);
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for (int i = 0; i < numFrames; i++) {
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__m128 x00 = _mm_loadu_ps(&src[4*i]);
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__m128 x01 = y00; // first biquad output
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// transposed Direct Form II
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__m128 x0 = _mm_loadu_ps(&src[4*i]);
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__m128 y0;
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y00 = _mm_add_ps(w10, _mm_mul_ps(x00, b00));
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y01 = _mm_add_ps(w11, _mm_mul_ps(x01, b01));
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y0 = _mm_add_ps(w1, _mm_mul_ps(x0, b0));
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w1 = _mm_add_ps(w2, _mm_mul_ps(x0, b1));
|
||||
w2 = _mm_mul_ps(x0, b2);
|
||||
w1 = _mm_sub_ps(w1, _mm_mul_ps(y0, a1));
|
||||
w2 = _mm_sub_ps(w2, _mm_mul_ps(y0, a2));
|
||||
w10 = _mm_add_ps(w20, _mm_mul_ps(x00, b10));
|
||||
w11 = _mm_add_ps(w21, _mm_mul_ps(x01, b11));
|
||||
|
||||
_mm_storeu_ps(&dst[4*i], y0);
|
||||
w20 = _mm_mul_ps(x00, b20);
|
||||
w21 = _mm_mul_ps(x01, b21);
|
||||
|
||||
w10 = _mm_sub_ps(w10, _mm_mul_ps(y00, a10));
|
||||
w11 = _mm_sub_ps(w11, _mm_mul_ps(y01, a11));
|
||||
|
||||
w20 = _mm_sub_ps(w20, _mm_mul_ps(y00, a20));
|
||||
w21 = _mm_sub_ps(w21, _mm_mul_ps(y01, a21));
|
||||
|
||||
_mm_storeu_ps(&dst[4*i], y01); // second biquad output
|
||||
}
|
||||
|
||||
// save state
|
||||
_mm_storeu_ps(state[0], w1);
|
||||
_mm_storeu_ps(state[1], w2);
|
||||
_mm_storeu_ps(&state[0][0], y00);
|
||||
_mm_storeu_ps(&state[1][0], w10);
|
||||
_mm_storeu_ps(&state[2][0], w20);
|
||||
|
||||
_mm_storeu_ps(&state[1][4], w11);
|
||||
_mm_storeu_ps(&state[2][4], w21);
|
||||
|
||||
_MM_SET_FLUSH_ZERO_MODE(ftz);
|
||||
}
|
||||
|
|
@ -345,56 +477,105 @@ static void interleave_4x4(float* src0, float* src1, float* src2, float* src3, f
|
|||
}
|
||||
}
|
||||
|
||||
// 4 channels (interleaved)
|
||||
static void biquad_4x4(float* src, float* dst, float coef[5][4], float state[2][4], int numFrames) {
|
||||
// process 2 cascaded biquads on 4 channels (interleaved)
|
||||
// biquads are computed in parallel, by adding one sample of delay
|
||||
static void biquad2_4x4(float* src, float* dst, float coef[5][8], float state[3][8], int numFrames) {
|
||||
|
||||
// channel 0
|
||||
float w10 = state[0][0];
|
||||
float w20 = state[1][0];
|
||||
// restore state
|
||||
float y00 = state[0][0];
|
||||
float w10 = state[1][0];
|
||||
float w20 = state[2][0];
|
||||
|
||||
float y01 = state[0][1];
|
||||
float w11 = state[1][1];
|
||||
float w21 = state[2][1];
|
||||
|
||||
float y02 = state[0][2];
|
||||
float w12 = state[1][2];
|
||||
float w22 = state[2][2];
|
||||
|
||||
float y03 = state[0][3];
|
||||
float w13 = state[1][3];
|
||||
float w23 = state[2][3];
|
||||
|
||||
float y04;
|
||||
float w14 = state[1][4];
|
||||
float w24 = state[2][4];
|
||||
|
||||
float y05;
|
||||
float w15 = state[1][5];
|
||||
float w25 = state[2][5];
|
||||
|
||||
float y06;
|
||||
float w16 = state[1][6];
|
||||
float w26 = state[2][6];
|
||||
|
||||
float y07;
|
||||
float w17 = state[1][7];
|
||||
float w27 = state[2][7];
|
||||
|
||||
// first biquad coefs
|
||||
float b00 = coef[0][0];
|
||||
float b10 = coef[1][0];
|
||||
float b20 = coef[2][0];
|
||||
float a10 = coef[3][0];
|
||||
float a20 = coef[4][0];
|
||||
|
||||
// channel 1
|
||||
float w11 = state[0][1];
|
||||
float w21 = state[1][1];
|
||||
|
||||
float b01 = coef[0][1];
|
||||
float b11 = coef[1][1];
|
||||
float b21 = coef[2][1];
|
||||
float a11 = coef[3][1];
|
||||
float a21 = coef[4][1];
|
||||
|
||||
// channel 2
|
||||
float w12 = state[0][2];
|
||||
float w22 = state[1][2];
|
||||
|
||||
float b02 = coef[0][2];
|
||||
float b12 = coef[1][2];
|
||||
float b22 = coef[2][2];
|
||||
float a12 = coef[3][2];
|
||||
float a22 = coef[4][2];
|
||||
|
||||
// channel 3
|
||||
float w13 = state[0][3];
|
||||
float w23 = state[1][3];
|
||||
|
||||
float b03 = coef[0][3];
|
||||
float b13 = coef[1][3];
|
||||
float b23 = coef[2][3];
|
||||
float a13 = coef[3][3];
|
||||
float a23 = coef[4][3];
|
||||
|
||||
// second biquad coefs
|
||||
float b04 = coef[0][4];
|
||||
float b14 = coef[1][4];
|
||||
float b24 = coef[2][4];
|
||||
float a14 = coef[3][4];
|
||||
float a24 = coef[4][4];
|
||||
|
||||
float b05 = coef[0][5];
|
||||
float b15 = coef[1][5];
|
||||
float b25 = coef[2][5];
|
||||
float a15 = coef[3][5];
|
||||
float a25 = coef[4][5];
|
||||
|
||||
float b06 = coef[0][6];
|
||||
float b16 = coef[1][6];
|
||||
float b26 = coef[2][6];
|
||||
float a16 = coef[3][6];
|
||||
float a26 = coef[4][6];
|
||||
|
||||
float b07 = coef[0][7];
|
||||
float b17 = coef[1][7];
|
||||
float b27 = coef[2][7];
|
||||
float a17 = coef[3][7];
|
||||
float a27 = coef[4][7];
|
||||
|
||||
for (int i = 0; i < numFrames; i++) {
|
||||
|
||||
// first biquad input
|
||||
float x00 = src[4*i+0] + 1.0e-20f; // prevent denormals
|
||||
float x01 = src[4*i+1] + 1.0e-20f;
|
||||
float x02 = src[4*i+2] + 1.0e-20f;
|
||||
float x03 = src[4*i+3] + 1.0e-20f;
|
||||
float y00, y01, y02, y03;
|
||||
// second biquad input is previous output
|
||||
float x04 = y00;
|
||||
float x05 = y01;
|
||||
float x06 = y02;
|
||||
float x07 = y03;
|
||||
|
||||
// transposed Direct Form II
|
||||
y00 = b00 * x00 + w10;
|
||||
|
|
@ -413,24 +594,57 @@ static void biquad_4x4(float* src, float* dst, float coef[5][4], float state[2][
|
|||
w13 = b13 * x03 - a13 * y03 + w23;
|
||||
w23 = b23 * x03 - a23 * y03;
|
||||
|
||||
dst[4*i+0] = y00;
|
||||
dst[4*i+1] = y01;
|
||||
dst[4*i+2] = y02;
|
||||
dst[4*i+3] = y03;
|
||||
// transposed Direct Form II
|
||||
y04 = b04 * x04 + w14;
|
||||
w14 = b14 * x04 - a14 * y04 + w24;
|
||||
w24 = b24 * x04 - a24 * y04;
|
||||
|
||||
y05 = b05 * x05 + w15;
|
||||
w15 = b15 * x05 - a15 * y05 + w25;
|
||||
w25 = b25 * x05 - a25 * y05;
|
||||
|
||||
y06 = b06 * x06 + w16;
|
||||
w16 = b16 * x06 - a16 * y06 + w26;
|
||||
w26 = b26 * x06 - a26 * y06;
|
||||
|
||||
y07 = b07 * x07 + w17;
|
||||
w17 = b17 * x07 - a17 * y07 + w27;
|
||||
w27 = b27 * x07 - a27 * y07;
|
||||
|
||||
dst[4*i+0] = y04; // second biquad output
|
||||
dst[4*i+1] = y05;
|
||||
dst[4*i+2] = y06;
|
||||
dst[4*i+3] = y07;
|
||||
}
|
||||
|
||||
// save state
|
||||
state[0][0] = w10;
|
||||
state[1][0] = w20;
|
||||
state[0][0] = y00;
|
||||
state[1][0] = w10;
|
||||
state[2][0] = w20;
|
||||
|
||||
state[0][1] = w11;
|
||||
state[1][1] = w21;
|
||||
state[0][1] = y01;
|
||||
state[1][1] = w11;
|
||||
state[2][1] = w21;
|
||||
|
||||
state[0][2] = w12;
|
||||
state[1][2] = w22;
|
||||
state[0][2] = y02;
|
||||
state[1][2] = w12;
|
||||
state[2][2] = w22;
|
||||
|
||||
state[0][3] = w13;
|
||||
state[1][3] = w23;
|
||||
state[0][3] = y03;
|
||||
state[1][3] = w13;
|
||||
state[2][3] = w23;
|
||||
|
||||
state[1][4] = w14;
|
||||
state[2][4] = w24;
|
||||
|
||||
state[1][5] = w15;
|
||||
state[2][5] = w25;
|
||||
|
||||
state[1][6] = w16;
|
||||
state[2][6] = w26;
|
||||
|
||||
state[1][7] = w17;
|
||||
state[2][7] = w27;
|
||||
}
|
||||
|
||||
// crossfade 4 inputs into 2 outputs with accumulation (interleaved)
|
||||
|
|
@ -468,9 +682,63 @@ static void ThiranBiquad(float f, float& b0, float& b1, float& b2, float& a1, fl
|
|||
b2 = 1.0f;
|
||||
}
|
||||
|
||||
// compute new filters for a given azimuth and gain
|
||||
static void setAzimuthAndGain(float firCoef[4][HRTF_TAPS], float bqCoef[5][4], int delay[4],
|
||||
int index, float azimuth, float gain, int channel) {
|
||||
// split x into exponent and fraction (0.0f to 1.0f)
|
||||
static void splitf(float x, int& expn, float& frac) {
|
||||
|
||||
union { float f; int i; } mant, bits = { x };
|
||||
const int IEEE754_MANT_BITS = 23;
|
||||
const int IEEE754_EXPN_BIAS = 127;
|
||||
|
||||
mant.i = bits.i & ((1 << IEEE754_MANT_BITS) - 1);
|
||||
mant.i |= (IEEE754_EXPN_BIAS << IEEE754_MANT_BITS);
|
||||
|
||||
frac = mant.f - 1.0f;
|
||||
expn = (bits.i >> IEEE754_MANT_BITS) - IEEE754_EXPN_BIAS;
|
||||
}
|
||||
|
||||
static void distanceBiquad(float distance, float& b0, float& b1, float& b2, float& a1, float& a2) {
|
||||
|
||||
//
|
||||
// Computed from a lookup table quantized to distance = 2^(N/4)
|
||||
// and reconstructed by piecewise linear interpolation.
|
||||
// Approximation error < 0.25dB
|
||||
//
|
||||
|
||||
float x = distance;
|
||||
x = MIN(MAX(x, 1.0f), 1<<30);
|
||||
x *= x;
|
||||
x *= x; // x = distance^4
|
||||
|
||||
// split x into e and frac, such that x = 2^(e+0) + frac * (2^(e+1) - 2^(e+0))
|
||||
int e;
|
||||
float frac;
|
||||
splitf(x, e, frac);
|
||||
|
||||
// clamp to table limits
|
||||
if (e < 0) {
|
||||
e = 0;
|
||||
frac = 0.0f;
|
||||
}
|
||||
if (e > NLOWPASS-2) {
|
||||
e = NLOWPASS-2;
|
||||
frac = 1.0f;
|
||||
}
|
||||
assert(frac >= 0.0f);
|
||||
assert(frac <= 1.0f);
|
||||
assert(e+0 >= 0);
|
||||
assert(e+1 < NLOWPASS);
|
||||
|
||||
// piecewise linear interpolation
|
||||
b0 = lowpassTable[e+0][0] + frac * (lowpassTable[e+1][0] - lowpassTable[e+0][0]);
|
||||
b1 = lowpassTable[e+0][1] + frac * (lowpassTable[e+1][1] - lowpassTable[e+0][1]);
|
||||
b2 = lowpassTable[e+0][2] + frac * (lowpassTable[e+1][2] - lowpassTable[e+0][2]);
|
||||
a1 = lowpassTable[e+0][3] + frac * (lowpassTable[e+1][3] - lowpassTable[e+0][3]);
|
||||
a2 = lowpassTable[e+0][4] + frac * (lowpassTable[e+1][4] - lowpassTable[e+0][4]);
|
||||
}
|
||||
|
||||
// compute new filters for a given azimuth, distance and gain
|
||||
static void setFilters(float firCoef[4][HRTF_TAPS], float bqCoef[5][8], int delay[4],
|
||||
int index, float azimuth, float distance, float gain, int channel) {
|
||||
|
||||
// convert from radians to table units
|
||||
azimuth *= HRTF_AZIMUTHS / TWOPI;
|
||||
|
|
@ -551,9 +819,26 @@ static void setAzimuthAndGain(float firCoef[4][HRTF_TAPS], float bqCoef[5][4], i
|
|||
bqCoef[4][channel+1] = a2;
|
||||
delay[channel+1] = itdi;
|
||||
}
|
||||
|
||||
//
|
||||
// Second biquad implements the distance filter.
|
||||
//
|
||||
distanceBiquad(distance, b0, b1, b2, a1, a2);
|
||||
|
||||
bqCoef[0][channel+4] = b0;
|
||||
bqCoef[1][channel+4] = b1;
|
||||
bqCoef[2][channel+4] = b2;
|
||||
bqCoef[3][channel+4] = a1;
|
||||
bqCoef[4][channel+4] = a2;
|
||||
|
||||
bqCoef[0][channel+5] = b0;
|
||||
bqCoef[1][channel+5] = b1;
|
||||
bqCoef[2][channel+5] = b2;
|
||||
bqCoef[3][channel+5] = a1;
|
||||
bqCoef[4][channel+5] = a2;
|
||||
}
|
||||
|
||||
void AudioHRTF::render(int16_t* input, float* output, int index, float azimuth, float gain, int numFrames) {
|
||||
void AudioHRTF::render(int16_t* input, float* output, int index, float azimuth, float distance, float gain, int numFrames) {
|
||||
|
||||
assert(index >= 0);
|
||||
assert(index < HRTF_TABLES);
|
||||
|
|
@ -562,18 +847,19 @@ void AudioHRTF::render(int16_t* input, float* output, int index, float azimuth,
|
|||
float in[HRTF_TAPS + HRTF_BLOCK]; // mono
|
||||
float firCoef[4][HRTF_TAPS]; // 4-channel
|
||||
float firBuffer[4][HRTF_DELAY + HRTF_BLOCK]; // 4-channel
|
||||
float bqCoef[5][4]; // 4-channel (interleaved)
|
||||
float bqCoef[5][8]; // 4-channel (interleaved)
|
||||
float bqBuffer[4 * HRTF_BLOCK]; // 4-channel (interleaved)
|
||||
int delay[4]; // 4-channel (interleaved)
|
||||
|
||||
// to avoid polluting the cache, old filters are recomputed instead of stored
|
||||
setAzimuthAndGain(firCoef, bqCoef, delay, index, _azimuthState, _gainState, L0);
|
||||
setFilters(firCoef, bqCoef, delay, index, _azimuthState, _distanceState, _gainState, L0);
|
||||
|
||||
// compute new filters
|
||||
setAzimuthAndGain(firCoef, bqCoef, delay, index, azimuth, gain, L1);
|
||||
setFilters(firCoef, bqCoef, delay, index, azimuth, distance, gain, L1);
|
||||
|
||||
// new parameters become old
|
||||
_azimuthState = azimuth;
|
||||
_distanceState = distance;
|
||||
_gainState = gain;
|
||||
|
||||
// convert mono input to float
|
||||
|
|
@ -611,14 +897,25 @@ void AudioHRTF::render(int16_t* input, float* output, int index, float azimuth,
|
|||
&firBuffer[R1][HRTF_DELAY] - delay[R1],
|
||||
bqBuffer, HRTF_BLOCK);
|
||||
|
||||
// process old/new fractional delay
|
||||
biquad_4x4(bqBuffer, bqBuffer, bqCoef, _bqState, HRTF_BLOCK);
|
||||
// process old/new biquads
|
||||
biquad2_4x4(bqBuffer, bqBuffer, bqCoef, _bqState, HRTF_BLOCK);
|
||||
|
||||
// new state becomes old
|
||||
_bqState[0][L0] = _bqState[0][L1];
|
||||
_bqState[1][L0] = _bqState[1][L1];
|
||||
_bqState[2][L0] = _bqState[2][L1];
|
||||
|
||||
_bqState[0][R0] = _bqState[0][R1];
|
||||
_bqState[1][R0] = _bqState[1][R1];
|
||||
_bqState[2][R0] = _bqState[2][R1];
|
||||
|
||||
_bqState[0][L2] = _bqState[0][L3];
|
||||
_bqState[1][L2] = _bqState[1][L3];
|
||||
_bqState[2][L2] = _bqState[2][L3];
|
||||
|
||||
_bqState[0][R2] = _bqState[0][R3];
|
||||
_bqState[1][R2] = _bqState[1][R3];
|
||||
_bqState[2][R2] = _bqState[2][R3];
|
||||
|
||||
// crossfade old/new output and accumulate
|
||||
crossfade_4x2(bqBuffer, output, crossfadeTable, HRTF_BLOCK);
|
||||
|
|
@ -626,15 +923,16 @@ void AudioHRTF::render(int16_t* input, float* output, int index, float azimuth,
|
|||
_silentState = false;
|
||||
}
|
||||
|
||||
void AudioHRTF::renderSilent(int16_t* input, float* output, int index, float azimuth, float gain, int numFrames) {
|
||||
void AudioHRTF::renderSilent(int16_t* input, float* output, int index, float azimuth, float distance, float gain, int numFrames) {
|
||||
|
||||
// process the first silent block, to flush internal state
|
||||
if (!_silentState) {
|
||||
render(input, output, index, azimuth, gain, numFrames);
|
||||
render(input, output, index, azimuth, distance, gain, numFrames);
|
||||
}
|
||||
|
||||
// new parameters become old
|
||||
_azimuthState = azimuth;
|
||||
_distanceState = distance;
|
||||
_gainState = gain;
|
||||
|
||||
_silentState = true;
|
||||
|
|
|
|||
|
|
@ -21,7 +21,7 @@ static const int HRTF_TABLES = 25; // number of HRTF subjects
|
|||
static const int HRTF_DELAY = 24; // max ITD in samples (1.0ms at 24KHz)
|
||||
static const int HRTF_BLOCK = 256; // block processing size
|
||||
|
||||
static const float HRTF_GAIN = 0.5f; // HRTF global gain adjustment
|
||||
static const float HRTF_GAIN = 1.0f; // HRTF global gain adjustment
|
||||
|
||||
class AudioHRTF {
|
||||
|
||||
|
|
@ -33,15 +33,16 @@ public:
|
|||
// output: interleaved stereo mix buffer (accumulates into existing output)
|
||||
// index: HRTF subject index
|
||||
// azimuth: clockwise panning angle in radians
|
||||
// distance: source distance in meters
|
||||
// gain: gain factor for distance attenuation
|
||||
// numFrames: must be HRTF_BLOCK in this version
|
||||
//
|
||||
void render(int16_t* input, float* output, int index, float azimuth, float gain, int numFrames);
|
||||
void render(int16_t* input, float* output, int index, float azimuth, float distance, float gain, int numFrames);
|
||||
|
||||
//
|
||||
// Fast path when input is known to be silent
|
||||
//
|
||||
void renderSilent(int16_t* input, float* output, int index, float azimuth, float gain, int numFrames);
|
||||
void renderSilent(int16_t* input, float* output, int index, float azimuth, float distance, float gain, int numFrames);
|
||||
|
||||
private:
|
||||
AudioHRTF(const AudioHRTF&) = delete;
|
||||
|
|
@ -49,10 +50,10 @@ private:
|
|||
|
||||
// SIMD channel assignmentS
|
||||
enum Channel {
|
||||
L0,
|
||||
R0,
|
||||
L1,
|
||||
R1
|
||||
L0, R0,
|
||||
L1, R1,
|
||||
L2, R2,
|
||||
L3, R3
|
||||
};
|
||||
|
||||
// For best cache utilization when processing thousands of instances, only
|
||||
|
|
@ -64,11 +65,12 @@ private:
|
|||
// integer delay history
|
||||
float _delayState[4][HRTF_DELAY] = {};
|
||||
|
||||
// fractional delay history
|
||||
float _bqState[2][4] = {};
|
||||
// biquad history
|
||||
float _bqState[3][8] = {};
|
||||
|
||||
// parameter history
|
||||
float _azimuthState = 0.0f;
|
||||
float _distanceState = 0.0f;
|
||||
float _gainState = 0.0f;
|
||||
|
||||
bool _silentState = false;
|
||||
|
|
|
|||
Loading…
Reference in a new issue