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Merged
dooly123 merged 3 commits into from
Feb 19, 2026
Merged

AGC improvements for LocalMicrophoneDriver #539

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ed4f641
Add hold timer and noise floor to AGC
s-ilent Feb 19, 2026
b61e8db
AGC, process audio in smaller chunks
s-ilent Feb 19, 2026
fd0fe44
agc: Add names for constants
s-ilent Feb 19, 2026
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100 changes: 67 additions & 33 deletions Basis/Packages/com.basis.framework/Drivers/Local/BasisLocalMicrophoneDriver.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,12 @@ public static class BasisLocalMicrophoneDriver
private static int warmupSamples = 0;
private static bool inWarmup = false;
private static float agcGainDb = 0f;

public const int ProcessFrameSize = 960; // 20ms at 48kHz
public const int DenoiserFrameSize = 480; // 10ms at 48kHz

private static float _agcHoldTimer = 0f;

private static float[] _denoiseDry;
private static float[] _tmp480;

Expand Down Expand Up @@ -446,17 +452,17 @@ public static void ProcessAudioData(int posSnapshot)
}

int dataLength = GetDataLength(bufferLength, head, posSnapshot);
while (dataLength >= SampleRate)
while (dataLength >= ProcessFrameSize)
{
int remain = bufferLength - head;
if (remain < SampleRate)
if (remain < ProcessFrameSize)
{
Array.Copy(microphoneBufferArray, head, processBufferArray, 0, remain);
Array.Copy(microphoneBufferArray, 0, processBufferArray, remain, SampleRate - remain);
Array.Copy(microphoneBufferArray, 0, processBufferArray, remain, ProcessFrameSize - remain);
}
else
{
Array.Copy(microphoneBufferArray, head, processBufferArray, 0, SampleRate);
Array.Copy(microphoneBufferArray, head, processBufferArray, 0, ProcessFrameSize);
}

// --- Optional AGC ---
Expand All @@ -468,7 +474,7 @@ public static void ProcessAudioData(int posSnapshot)
float agcAmp = DbToAmp(agcGainDb);
if (!Mathf.Approximately(agcAmp, 1f))
{
for (int i = 0; i < SampleRate; i++)
for (int i = 0; i < ProcessFrameSize; i++)
processBufferArray[i] *= agcAmp;
}
}
Expand Down Expand Up @@ -496,8 +502,8 @@ public static void ProcessAudioData(int posSnapshot)
Interlocked.Exchange(ref _scheduleMainHasAudio, 0);
}

head = (head + SampleRate) % bufferLength;
dataLength -= SampleRate;
head = (head + ProcessFrameSize) % bufferLength;
dataLength -= ProcessFrameSize;
}
}

Expand All @@ -516,12 +522,13 @@ public static void AdjustVolume(SMDMicrophone.MicSettings s)
public static float GetRMS()
{
double sum = 0.0;
for (int i = 0; i < SampleRate; i++)
int len = processBufferArray.Length;
for (int i = 0; i < len; i++)
{
float v = processBufferArray[i];
sum += v * v;
}
return Mathf.Sqrt((float)(sum / SampleRate));
return Mathf.Sqrt((float)(sum / len));
}

public static int GetDataLength(int len, int h, int pos)
Expand All @@ -548,35 +555,32 @@ public static void ApplyDeNoise(SMDMicrophone.MicSettings s)
if (_denoiseDry == null || _denoiseDry.Length != processBufferArray.Length)
CreateOrResizeArray(processBufferArray.Length, ref _denoiseDry);

Array.Copy(processBufferArray, _denoiseDry, SampleRate);
Array.Copy(processBufferArray, _denoiseDry, ProcessFrameSize);

const int hop = 480;
if (SampleRate == hop)
{
Denoiser?.Denoise(processBufferArray);
}
else
int offset = 0;

while (offset < ProcessFrameSize)
{
if (_tmp480 == null || _tmp480.Length != hop) _tmp480 = new float[hop];
// Copy from process buffer to denoiser buffer
// Todo: This is a little fragile since it relies on DenoiserFrameSize being 480
if (_tmp480 == null || _tmp480.Length != DenoiserFrameSize)
_tmp480 = new float[DenoiserFrameSize];

int o = 0;
while (o < SampleRate)
{
int n = Math.Min(hop, SampleRate - o);
Array.Clear(_tmp480, 0, hop);
Array.Copy(processBufferArray, o, _tmp480, 0, n);
Denoiser?.Denoise(_tmp480);
Array.Copy(_tmp480, 0, processBufferArray, o, n);
o += n;
}
Array.Copy(processBufferArray, offset, _tmp480, 0, DenoiserFrameSize);

Denoiser?.Denoise(_tmp480);

Array.Copy(_tmp480, 0, processBufferArray, offset, DenoiserFrameSize);

offset += DenoiserFrameSize;
}

float makeup = DbToAmp(s.DenoiseMakeupDb);
float wet = Mathf.Clamp01(s.DenoiseWet);

if (!Mathf.Approximately(wet, 1f) || !Mathf.Approximately(s.DenoiseMakeupDb, 0f))
{
for (int i = 0; i < SampleRate; i++)
for (int i = 0; i < ProcessFrameSize; i++)
{
float den = processBufferArray[i] * makeup;
processBufferArray[i] = Mathf.Lerp(_denoiseDry[i], den, wet);
Expand All @@ -586,10 +590,21 @@ public static void ApplyDeNoise(SMDMicrophone.MicSettings s)

public static void RollingRMS()
{
float rms = GetRMS();
rmsValues[rmsIndex] = rms;
double sumSq = 0.0;
int len = processBufferArray.Length;
for (int i = 0; i < len; i++)
{
float v = processBufferArray[i];
sumSq += v * v;
}
float currentMeanSq = (float)(sumSq / len);

rmsValues[rmsIndex] = currentMeanSq;
rmsIndex = (rmsIndex + 1) % LocalOpusSettings.rmsWindowSize;
averageRms = rmsValues.Average();

float averagePower = rmsValues.Average();

averageRms = Mathf.Sqrt(averagePower);
}

public static bool IsTransmitWorthy()
Expand All @@ -601,13 +616,32 @@ public static bool IsTransmitWorthy()

private static void UpdateAgc(float frameRms, float targetRms, float maxGainDb, float attack, float release)
{
const float agcDecaySpeed = 0.020f; // ProcessFrameSize / 48000;
const float agcHoldTime = 0.400f;

if (frameRms <= 1e-6f) frameRms = 1e-6f;

if (_agcHoldTimer > 0f) _agcHoldTimer -= agcDecaySpeed;

// Skip updating gain if the sound is too quiet (below -50dB)
if (frameRms < 0.003f) return;

float neededDb = 20f * Mathf.Log10(Mathf.Max(1e-6f, targetRms) / frameRms);
neededDb = Mathf.Clamp(neededDb, -maxGainDb, maxGainDb);

float k = (neededDb > agcGainDb) ? Mathf.Clamp01(attack) : Mathf.Clamp01(release);
agcGainDb = Mathf.Lerp(agcGainDb, neededDb, k);
// The timer provides a cooldown period when the audio hits a new peak volume before applying additional correction.
if (neededDb < agcGainDb)
{
agcGainDb = Mathf.Lerp(agcGainDb, neededDb, Mathf.Clamp01(attack));
_agcHoldTimer = agcHoldTime;
}
else
{
if (_agcHoldTimer <= 0f)
{
agcGainDb = Mathf.Lerp(agcGainDb, neededDb, Mathf.Clamp01(release));
}
}
}

private static void CreateOrResizeArray(int length, ref float[] arr)
Expand Down
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