Method calculateKernelsForAzimuthElevation

src/internal/src/HRTFPanner.cpp:267–329

}

bool HRTFElevation::calculateKernelsForAzimuthElevation(
    HRTFDatabaseInfo * info, int azimuth, int elevation, 
    std::shared_ptr<HRTFKernel> & kernelL, std::shared_ptr<HRTFKernel> & kernelR)
{
    // Valid values for azimuth are 0 -> 345 in 15 degree increments.
    // Valid values for elevation are -45 -> +90 in 15 degree increments.

    bool isAzimuthGood = azimuth >= 0 && azimuth <= 345 && (azimuth / 15) * 15 == azimuth;
    ASSERT(isAzimuthGood);
    if (!isAzimuthGood) return false;

    bool isElevationGood = elevation >= -45 && elevation <= 90 && (elevation / 15) * 15 == elevation;
    ASSERT(isElevationGood);
    if (!isElevationGood) return false;

    // Construct the resource name from the subject name, azimuth, and elevation, for example:
    // "IRC_Composite_C_R0195_T015_P000"
    int positiveElevation = elevation < 0 ? elevation + 360 : elevation;

    char tempStr[16];

    // Located in $searchPath / [format] .wav
    // @tofix - this assumes we want to open this path and read via libnyquist fopen.
    // ... will need to change for Android. Maybe MakeBusFromInternalResource / along 
    // with a LoadInternalResources required by LabSound
    sprintf(tempStr, "%03d_P%03d", azimuth, positiveElevation);
    std::string resourceName = info->searchPath + "/" + "IRC_" + info->subjectName + "_C_R0195_T" + tempStr + ".wav";

    std::shared_ptr<AudioBus> impulseResponse = lab::MakeBusFromFile(resourceName.c_str(), false);

    if (!impulseResponse)
    {
        LOG_ERROR("impulse not found %s (bad path?)", resourceName.c_str());
        return false;
    }

    // The impulse files are 44.1k so we need to resample them if the graph is playing back at any other rate
    if (info->sampleRate != 44100.0f)
    {
        std::unique_ptr<AudioBus> resampledImpulseResponse = AudioBus::createBySampleRateConverting(impulseResponse.get(), false, info->sampleRate);
        impulseResponse = std::move(resampledImpulseResponse);
        // LOG_VERBOSE("converting %s impulse to %f hz", resourceName.c_str(), info->sampleRate);
    }

    // Check number of channels. For now these are fixed and known.
    bool isBusGood = (impulseResponse->numberOfChannels() == Channels::Stereo);

    ASSERT(isBusGood);
    if (!isBusGood)
    {
        return false;
    }

    AudioChannel * leftEarImpulseResponse = impulseResponse->channelByType(Channel::Left);
    AudioChannel * rightEarImpulseResponse = impulseResponse->channelByType(Channel::Right);

    // Note that depending on the fftSize returned by the panner, we may be truncating the impulse response we just loaded in.
    const int fftSize = HRTFPanner::fftSizeForSampleRate(info->sampleRate);