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Remove glitching from the Flanger and Delay plugins (#3524)

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The previous delay code was incorrectly not utalising the whole buffer, causing glitches when
incressing the delay time, due to outputting incorrect data, This was apparent when using the
lfo in the Delay and Flanger plugins.

This has been rectified. The read index is now offset from the write index. and the complete buffer is used in a circular fashon.

Flanger - resolved issue where the lfo could create negative delay lengths
This commit is contained in:
Dave French
2017-05-17 11:18:47 +01:00
committed by Oskar Wallgren
parent b0ae31c2ff
commit b432707b9b
5 changed files with 20 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
plugins/Delay/StereoDelay.cpp
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@@ -36,7 +36,7 @@ StereoDelay::StereoDelay( int maxTime, int sampleRate )
m_maxLength = maxTime * sampleRate;
m_length = m_maxLength;
m_index = 0;
m_writeIndex = 0;
m_feedback = 0.0f;
setSampleRate( sampleRate );
}
@@ -57,13 +57,13 @@ StereoDelay::~StereoDelay()
void StereoDelay::tick( sampleFrame frame )
{
m_index = ( int )m_length > 0
? ( m_index + 1 ) % ( int ) m_length
: m_index;
float lOut = m_buffer[ m_index ][ 0 ];
float rOut = m_buffer[ m_index ] [1 ];
m_buffer[ m_index ][ 0 ] = frame[ 0 ] + ( lOut * m_feedback );
m_buffer[ m_index ][ 1 ] = frame[ 1 ] + ( rOut * m_feedback );
m_writeIndex = ( m_writeIndex + 1 ) % ( int )m_maxLength;
int readIndex = m_writeIndex - m_length;
if (readIndex < 0 ) { readIndex += m_maxLength; }
float lOut = m_buffer[ readIndex ][ 0 ];
float rOut = m_buffer[ readIndex ] [1 ];
m_buffer[ m_writeIndex ][ 0 ] = frame[ 0 ] + ( lOut * m_feedback );
m_buffer[ m_writeIndex ][ 1 ] = frame[ 1 ] + ( rOut * m_feedback );
frame[ 0 ] = lOut;
frame[ 1 ] = rOut;
}
@@ -71,6 +71,8 @@ void StereoDelay::tick( sampleFrame frame )
void StereoDelay::setSampleRate( int sampleRate )
{
if( m_buffer )

2
plugins/Delay/StereoDelay.h
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@@ -52,7 +52,7 @@ private:
sampleFrame* m_buffer;
int m_maxLength;
float m_length;
int m_index;
int m_writeIndex;
float m_feedback;
float m_maxTime;
};

4
plugins/Flanger/FlangerEffect.cpp
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@@ -107,8 +107,8 @@ bool FlangerEffect::processAudioBuffer( sampleFrame *buf, const fpp_t frames )
dryS[0] = buf[f][0];
dryS[1] = buf[f][1];
m_lfo->tick(&leftLfo, &rightLfo);
m_lDelay->setLength( ( float )length + ( amplitude * leftLfo ) );
m_rDelay->setLength( ( float )length+ ( amplitude * rightLfo ) );
m_lDelay->setLength( ( float )length + amplitude * (leftLfo+1.0) );
m_rDelay->setLength( ( float )length + amplitude * (rightLfo+1.0) );
if(invertFeedback)
{
m_lDelay->tick( &buf[f][1] );

12
plugins/Flanger/MonoDelay.cpp
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@@ -34,7 +34,7 @@ MonoDelay::MonoDelay( int maxTime , int sampleRate )
m_maxLength = maxTime * sampleRate;
m_length = m_maxLength;
m_index = 0;
m_writeIndex = 0;
m_feedback = 0.0f;
setSampleRate( sampleRate );
}
@@ -54,11 +54,11 @@ MonoDelay::~MonoDelay()
void MonoDelay::tick( sample_t* sample )
{
m_index = ( int )m_length > 0
? ( m_index + 1 ) % ( int )m_length
: m_index;
float out = m_buffer[ m_index ];
m_buffer[ m_index ] = *sample + ( out * m_feedback );
m_writeIndex = ( m_writeIndex + 1 ) % ( int )m_maxLength;
int readIndex = m_writeIndex - m_length;
if (readIndex < 0 ) { readIndex += m_maxLength; }
float out = m_buffer[ readIndex ];
m_buffer[ m_writeIndex ] = *sample + ( out * m_feedback );
*sample = out;
}

2
plugins/Flanger/MonoDelay.h
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@@ -52,7 +52,7 @@ private:
sample_t* m_buffer;
int m_maxLength;
float m_length;
int m_index;
int m_writeIndex;
float m_feedback;
float m_maxTime;
};