OpenMW/apps/openmw/mwsound/loudness.cpp

#include "loudness.hpp"

#include <cstdint>
#include <limits>
#include <algorithm>

#include "soundmanagerimp.hpp"

namespace MWSound
{

void Sound_Loudness::analyzeLoudness(const std::vector< char >& data)
{
    mQueue.insert( mQueue.end(), data.begin(), data.end() );
    if (!mQueue.size())
        return;

    int samplesPerSegment = static_cast<int>(mSampleRate / mSamplesPerSec);
    int numSamples = bytesToFrames(mQueue.size(), mChannelConfig, mSampleType);
    int advance = framesToBytes(1, mChannelConfig, mSampleType);


    int segment=0;
    int sample=0;
    while (segment < numSamples/samplesPerSegment)
    {
        float sum=0;
        int samplesAdded = 0;
        while (sample < numSamples && sample < (segment+1)*samplesPerSegment)
        {
            // get sample on a scale from -1 to 1
            float value = 0;
            if (mSampleType == SampleType_UInt8)
                value = ((char)(mQueue[sample*advance]^0x80))/128.f;
            else if (mSampleType == SampleType_Int16)
            {
                value = *reinterpret_cast<const int16_t*>(&mQueue[sample*advance]);
                value /= float(std::numeric_limits<int16_t>::max());
            }
            else if (mSampleType == SampleType_Float32)
            {
                value = *reinterpret_cast<const float*>(&mQueue[sample*advance]);
                value = std::clamp(value, -1.f, 1.f); // Float samples *should* be scaled to [-1,1] already.
            }

            sum += value*value;
            ++samplesAdded;
            ++sample;
        }

        float rms = 0; // root mean square
        if (samplesAdded > 0)
            rms = std::sqrt(sum / samplesAdded);
        mSamples.push_back(rms);
        ++segment;
    }

    mQueue.erase(mQueue.begin(), mQueue.begin() + sample*advance);
}


float Sound_Loudness::getLoudnessAtTime(float sec) const
{
    if(mSamplesPerSec <= 0.0f || mSamples.empty() || sec < 0.0f)
        return 0.0f;

    size_t index = std::clamp<size_t>(sec * mSamplesPerSec, 0, mSamples.size() - 1);
    return mSamples[index];
}

}