53 lines
1.7 KiB
C#
53 lines
1.7 KiB
C#
namespace ytLive.Services.Audio;
|
|
|
|
/// <summary>
|
|
/// Computes the smoothed mic level (0..1) from captured samples. Pure —
|
|
/// unit-tested; the <see cref="AudioMixer"/> only feeds it and forwards the
|
|
/// result. RMS-based so it tracks perceived loudness, smoothed so the meter
|
|
/// does not flicker.
|
|
/// </summary>
|
|
public sealed class AudioLevelMeter
|
|
{
|
|
private const float Smoothing = 0.2f;
|
|
private float _level;
|
|
|
|
public float Level => _level;
|
|
|
|
/// <summary>
|
|
/// Maps a linear level (0..1) onto the meter's display scale: -60 dBFS..0 dBFS
|
|
/// spread linearly across 0..1, with +10 dB of input amplification. Linear RMS
|
|
/// of real speech or game audio is ~0.01..0.1 (-40..-20 dBFS), which leaves a
|
|
/// flat (linear) meter looking dead; the log scale makes typical levels occupy
|
|
/// the bar and the amplification pushes real speech peaks into the red zone
|
|
/// (0.8+) at maxed volume instead of hovering at its edge. Inputs at or below
|
|
/// -60 dBFS (0.001 linear) read as zero — the meter never idles on background noise.
|
|
/// </summary>
|
|
public static float ToDisplay(float linear)
|
|
{
|
|
if (linear <= 0.001f)
|
|
return 0f;
|
|
var db = 20f * MathF.Log10(linear) + 10f;
|
|
return Math.Clamp(1f + db / 60f, 0f, 1f);
|
|
}
|
|
|
|
public float Push(AudioSample sample)
|
|
{
|
|
if (sample.Samples.Length == 0)
|
|
return _level;
|
|
|
|
double sumSquares = 0;
|
|
var count = 0;
|
|
foreach (var value in sample.Samples)
|
|
{
|
|
sumSquares += value * value;
|
|
count++;
|
|
}
|
|
|
|
var rms = (float)Math.Sqrt(sumSquares / count);
|
|
_level = _level * (1 - Smoothing) + rms * Smoothing;
|
|
return _level;
|
|
}
|
|
|
|
public void Reset() => _level = 0;
|
|
}
|