From 0ea6e47f2082f0130aef7a78f871e2215cf8fd13 Mon Sep 17 00:00:00 2001
From: Caleb Kemere <ckemere@gmail.com>
Date: Sat, 30 Nov 2013 22:05:29 -0600
Subject: [PATCH] Noise gate implemented. Scaling is still suspect, but sounds
reasonable with sample data.
---
Source/Processors/AudioNode.cpp | 23 ++++++++++++++---------
Source/Processors/AudioNode.h | 2 +-
2 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/Source/Processors/AudioNode.cpp b/Source/Processors/AudioNode.cpp
index cf5b9ae43..df989f10e 100755
--- a/Source/Processors/AudioNode.cpp
+++ b/Source/Processors/AudioNode.cpp
@@ -140,8 +140,7 @@ void AudioNode::setParameter(int parameterIndex, float newValue)
else if (parameterIndex == 2)
{
// noiseGateLevel level
- noiseGateLevel = newValue*0.01f; // not sure about this scaling???
- std::cout << "Changed noiseGateLevel: " << noiseGateLevel << std::endl;
+ noiseGateLevel = newValue; // in microVolts
}
else if (parameterIndex == 100)
@@ -294,6 +293,10 @@ void AudioNode::process(AudioSampleBuffer& buffer,
} // copying buffer
gain = volume/(float(0x7fff) * channelPointers[i-2]->bitVolts);
+ // - Maximum of "volume" is 10 (100 * 0.1)
+ // - float(0x7fff) is the maximum value that comes out of the preamp (15 bits of 1's)
+ // - bitVolts is the number of microvolts per bit - why are we dividing by this???
+ // So, maximum gain applied to maximum data would be 10/bitVolts
int remainingSamples = numSamplesExpected - samplesToCopy;
@@ -353,15 +356,17 @@ void AudioNode::process(AudioSampleBuffer& buffer,
}
- // HERE IS WHERE WE NEED TO NOISE GATE
+ // Simple implementation of a "noise gate" on audio output
float *leftChannelData = buffer.getSampleData(0);
float *rightChannelData = buffer.getSampleData(1);
- float gateLevel = noiseGateLevel/(float(0x7fff));
- for (int i=0; i < buffer.getNumSamples(); i++) {
- if (abs(leftChannelData[i]) < gateLevel)
- leftChannelData[i] = 0;
- if (abs(rightChannelData[i]) < gateLevel)
- rightChannelData[i] = 0;
+ // float gateLevel = (noiseGateLevel / channelPointers[i-2]->bitVolts) * gain; // uVolts scaled by gain
+ float gateLevel = noiseGateLevel * gain; // bits scaled by gain
+
+ for (int m=0; m < buffer.getNumSamples(); m++) {
+ if (fabs(leftChannelData[m]) < gateLevel)
+ leftChannelData[m] = 0;
+ if (fabs(rightChannelData[m]) < gateLevel)
+ rightChannelData[m] = 0;
}
}
}
diff --git a/Source/Processors/AudioNode.h b/Source/Processors/AudioNode.h
index 8a7d20b2c..8ebc5296d 100755
--- a/Source/Processors/AudioNode.h
+++ b/Source/Processors/AudioNode.h
@@ -103,7 +103,7 @@ private:
Array<int> leftChan;
Array<int> rightChan;
float volume;
- float noiseGateLevel;
+ float noiseGateLevel; // in microvolts
/** An array of pointers to the channels that feed into the AudioNode. */
Array<Channel*> channelPointers;
--
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