R128Net: EBU R128 loudness measurement for .NET, faster than C

Install

dotnet add package R128Net

Use

This program feeds 20 seconds of a stereo 1 kHz sine at -23 dBFS to a meter in blocks of 100 ms, then reads the integrated loudness, the loudness range and the true peak. It prints -23.0 LUFS, 0.0 LU and -23.0 dBTP.

using R128Net;

const int SampleRate = 48000;
const int BlockFrames = SampleRate / 10;

using LoudnessMeter meter = new(channels: 2, SampleRate,
    LoudnessModes.Integrated | LoudnessModes.LoudnessRange | LoudnessModes.TruePeak);

float[] block = new float[2 * BlockFrames];
for (int n = 0; n < 200; ++n)
{
    for (int i = 0; i < BlockFrames; ++i)
    {
        float value = (float)(0.0708 * Math.Sin(2.0 * Math.PI * 1000.0 * ((n * BlockFrames) + i) / SampleRate));
        block[2 * i] = value;
        block[(2 * i) + 1] = value;
    }

    meter.AddFrames(block);
}

Console.WriteLine($"Integrated loudness: {meter.IntegratedLoudness:F1} LUFS");
Console.WriteLine($"Loudness range: {meter.LoudnessRange:F1} LU");
Console.WriteLine($"True peak: {20.0 * Math.Log10(meter.GetTruePeak(0)):F1} dBTP");

What it does

Momentary, short-term and integrated loudness, as EBU R128 and ITU-R BS.1770 define them.
Loudness range, as EBU Tech 3342 defines it.
The relative threshold, and the loudness over any window up to a maximum you set.
Sample peak and true peak.
The histogram algorithm, and the aggregation of several meters into a single figure.
Input as 16-bit integers, 32-bit integers, single precision and double precision.

Why R128Net

Faster than the original C in every mode measured. The tables are in the performance section of the README.
No managed allocation. The garbage collector never observes the measurement path.
Verified against the original built with MSVC. In the test suite the loudness and the peaks match the original to the bit.
.NET 10, tested on x64 and ARM64, Windows and Linux. Native AOT ready. No native library to ship.

Install

Use

What it does

Why R128Net

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