diff options
Diffstat (limited to 'Alc/hrtf.c')
| -rw-r--r-- | Alc/hrtf.c | 214 |
1 files changed, 204 insertions, 10 deletions
@@ -58,6 +58,10 @@ struct Hrtf { static const ALchar magicMarker00[8] = "MinPHR00"; static const ALchar magicMarker01[8] = "MinPHR01"; +/* First value for pass-through coefficients (remaining are 0), used for omni- + * directional sounds. */ +static const ALfloat PassthruCoeff = 32767.0f * 0.707106781187f/*sqrt(0.5)*/; + static struct Hrtf *LoadedHrtfs = NULL; /* Calculate the elevation indices given the polar elevation in radians. @@ -84,12 +88,45 @@ static void CalcAzIndices(ALuint azcount, ALfloat az, ALuint *azidx, ALfloat *az *azmu = az - floorf(az); } +/* Calculates the normalized HRTF transition factor (delta) from the changes + * in gain and listener to source angle between updates. The result is a + * normalized delta factor that can be used to calculate moving HRIR stepping + * values. + */ +ALfloat CalcHrtfDelta(ALfloat oldGain, ALfloat newGain, const ALfloat olddir[3], const ALfloat newdir[3]) +{ + ALfloat gainChange, angleChange, change; + + // Calculate the normalized dB gain change. + newGain = maxf(newGain, 0.0001f); + oldGain = maxf(oldGain, 0.0001f); + gainChange = fabsf(log10f(newGain / oldGain) / log10f(0.0001f)); + + // Calculate the angle change only when there is enough gain to notice it. + angleChange = 0.0f; + if(gainChange > 0.0001f || newGain > 0.0001f) + { + // No angle change when the directions are equal or degenerate (when + // both have zero length). + if(newdir[0] != olddir[0] || newdir[1] != olddir[1] || newdir[2] != olddir[2]) + { + ALfloat dotp = olddir[0]*newdir[0] + olddir[1]*newdir[1] + olddir[2]*newdir[2]; + angleChange = acosf(clampf(dotp, -1.0f, 1.0f)) / F_PI; + } + } + + // Use the largest of the two changes for the delta factor, and apply a + // significance shaping function to it. + change = maxf(angleChange * 25.0f, gainChange) * 2.0f; + return minf(change, 1.0f); +} + /* Calculates static HRIR coefficients and delays for the given polar * elevation and azimuth in radians. Linear interpolation is used to * increase the apparent resolution of the HRIR data set. The coefficients * are also normalized and attenuated by the specified gain. */ -void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat (*coeffs)[2], ALuint *delays) +void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays) { ALuint evidx[2], lidx[4], ridx[4]; ALfloat mu[3], blend[4]; @@ -121,12 +158,12 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi blend[3] = ( mu[1]) * ( mu[2]); /* Calculate the HRIR delays using linear interpolation. */ - delays[0] = fastf2u(Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] + - Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3] + - 0.5f); - delays[1] = fastf2u(Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] + - Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3] + - 0.5f); + delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] + + Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) * + dirfact + 0.5f) << HRTFDELAY_BITS; + delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] + + Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) * + dirfact + 0.5f) << HRTFDELAY_BITS; /* Calculate the sample offsets for the HRIR indices. */ lidx[0] *= Hrtf->irSize; @@ -138,16 +175,173 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi ridx[2] *= Hrtf->irSize; ridx[3] *= Hrtf->irSize; - for(i = 0;i < Hrtf->irSize;i++) + /* Calculate the normalized and attenuated HRIR coefficients using linear + * interpolation when there is enough gain to warrant it. Zero the + * coefficients if gain is too low. + */ + if(gain > 0.0001f) { ALfloat c; + + i = 0; c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] + Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]); - coeffs[i][0] = c * (1.0f/32767.0f); + coeffs[i][0] = lerp(PassthruCoeff, c, dirfact) * gain * (1.0f/32767.0f); c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] + Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]); - coeffs[i][1] = c * (1.0f/32767.0f); + coeffs[i][1] = lerp(PassthruCoeff, c, dirfact) * gain * (1.0f/32767.0f); + + for(i = 1;i < Hrtf->irSize;i++) + { + c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] + + Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]); + coeffs[i][0] = lerp(0.0f, c, dirfact) * gain * (1.0f/32767.0f); + c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] + + Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]); + coeffs[i][1] = lerp(0.0f, c, dirfact) * gain * (1.0f/32767.0f); + } } + else + { + for(i = 0;i < Hrtf->irSize;i++) + { + coeffs[i][0] = 0.0f; + coeffs[i][1] = 0.0f; + } + } +} + +/* Calculates the moving HRIR target coefficients, target delays, and + * stepping values for the given polar elevation and azimuth in radians. + * Linear interpolation is used to increase the apparent resolution of the + * HRIR data set. The coefficients are also normalized and attenuated by the + * specified gain. Stepping resolution and count is determined using the + * given delta factor between 0.0 and 1.0. + */ +ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep) +{ + ALuint evidx[2], lidx[4], ridx[4]; + ALfloat mu[3], blend[4]; + ALfloat left, right; + ALfloat step; + ALuint i; + + /* Claculate elevation indices and interpolation factor. */ + CalcEvIndices(Hrtf->evCount, elevation, evidx, &mu[2]); + + for(i = 0;i < 2;i++) + { + ALuint azcount = Hrtf->azCount[evidx[i]]; + ALuint evoffset = Hrtf->evOffset[evidx[i]]; + ALuint azidx[2]; + + /* Calculate azimuth indices and interpolation factor for this elevation. */ + CalcAzIndices(azcount, azimuth, azidx, &mu[i]); + + /* Calculate a set of linear HRIR indices for left and right channels. */ + lidx[i*2 + 0] = evoffset + azidx[0]; + lidx[i*2 + 1] = evoffset + azidx[1]; + ridx[i*2 + 0] = evoffset + ((azcount-azidx[0]) % azcount); + ridx[i*2 + 1] = evoffset + ((azcount-azidx[1]) % azcount); + } + + // Calculate the stepping parameters. + delta = maxf(floorf(delta*(Hrtf->sampleRate*0.015f) + 0.5f), 1.0f); + step = 1.0f / delta; + + /* Calculate 4 blending weights for 2D bilinear interpolation. */ + blend[0] = (1.0f-mu[0]) * (1.0f-mu[2]); + blend[1] = ( mu[0]) * (1.0f-mu[2]); + blend[2] = (1.0f-mu[1]) * ( mu[2]); + blend[3] = ( mu[1]) * ( mu[2]); + + /* Calculate the HRIR delays using linear interpolation. Then calculate + * the delay stepping values using the target and previous running + * delays. + */ + left = (ALfloat)(delays[0] - (delayStep[0] * counter)); + right = (ALfloat)(delays[1] - (delayStep[1] * counter)); + + delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] + + Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) * + dirfact + 0.5f) << HRTFDELAY_BITS; + delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] + + Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) * + dirfact + 0.5f) << HRTFDELAY_BITS; + + delayStep[0] = fastf2i(step * (delays[0] - left)); + delayStep[1] = fastf2i(step * (delays[1] - right)); + + /* Calculate the sample offsets for the HRIR indices. */ + lidx[0] *= Hrtf->irSize; + lidx[1] *= Hrtf->irSize; + lidx[2] *= Hrtf->irSize; + lidx[3] *= Hrtf->irSize; + ridx[0] *= Hrtf->irSize; + ridx[1] *= Hrtf->irSize; + ridx[2] *= Hrtf->irSize; + ridx[3] *= Hrtf->irSize; + + /* Calculate the normalized and attenuated target HRIR coefficients using + * linear interpolation when there is enough gain to warrant it. Zero + * the target coefficients if gain is too low. Then calculate the + * coefficient stepping values using the target and previous running + * coefficients. + */ + if(gain > 0.0001f) + { + ALfloat c; + + i = 0; + left = coeffs[i][0] - (coeffStep[i][0] * counter); + right = coeffs[i][1] - (coeffStep[i][1] * counter); + + c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] + + Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]); + coeffs[i][0] = lerp(PassthruCoeff, c, dirfact) * gain * (1.0f/32767.0f);; + c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] + + Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]); + coeffs[i][1] = lerp(PassthruCoeff, c, dirfact) * gain * (1.0f/32767.0f);; + + coeffStep[i][0] = step * (coeffs[i][0] - left); + coeffStep[i][1] = step * (coeffs[i][1] - right); + + for(i = 1;i < Hrtf->irSize;i++) + { + left = coeffs[i][0] - (coeffStep[i][0] * counter); + right = coeffs[i][1] - (coeffStep[i][1] * counter); + + c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] + + Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]); + coeffs[i][0] = lerp(0.0f, c, dirfact) * gain * (1.0f/32767.0f);; + c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] + + Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]); + coeffs[i][1] = lerp(0.0f, c, dirfact) * gain * (1.0f/32767.0f);; + + coeffStep[i][0] = step * (coeffs[i][0] - left); + coeffStep[i][1] = step * (coeffs[i][1] - right); + } + } + else + { + for(i = 0;i < Hrtf->irSize;i++) + { + left = coeffs[i][0] - (coeffStep[i][0] * counter); + right = coeffs[i][1] - (coeffStep[i][1] * counter); + + coeffs[i][0] = 0.0f; + coeffs[i][1] = 0.0f; + + coeffStep[i][0] = step * -left; + coeffStep[i][1] = step * -right; + } + } + + /* The stepping count is the number of samples necessary for the HRIR to + * complete its transition. The mixer will only apply stepping for this + * many samples. + */ + return fastf2u(delta); } |