LFPViewer - fix mean+std calculation

Plugins/LfpDisplayNode/LfpChannelDisplay.cpp

@@ -243,7 +243,7 @@ void LfpChannelDisplay::pxPaint()
         double a = (canvasSplit->getYCoordMax(chan, index)/range*channelHeightFloat);
         double b = (canvasSplit->getYCoordMin(chan, index)/range*channelHeightFloat);
 
-        double mean = (canvasSplit->getMean(chan)/range*channelHeightFloat);
+        double mean = (canvasSplit->getScreenBufferMean(chan)/range*channelHeightFloat);
 
         if (drawWithOffsetCorrection)
         {
@@ -508,7 +508,7 @@ void LfpChannelDisplay::pxPaintHistory(int playhead, int rightEdge, int maxScree
         double a = (canvasSplit->getYCoordMax(chan, index) / range * channelHeightFloat);
         double b = (canvasSplit->getYCoordMin(chan, index) / range * channelHeightFloat);
 
-        double mean = (canvasSplit->getMean(chan) / range * channelHeightFloat);
+        double mean = (canvasSplit->getScreenBufferMean(chan) / range * channelHeightFloat);
 
         if (drawWithOffsetCorrection)
         {

Plugins/LfpDisplayNode/LfpChannelDisplayInfo.cpp

@@ -247,7 +247,7 @@ void LfpChannelDisplayInfo::paint(Graphics& g)
 
         g.setColour(Colours::grey);
         g.drawText(String(canvasSplit->getStd(chan)), 5, center+110,41,10,Justification::centred,false);
-        g.drawText(String(canvasSplit->getMean(chan)), 5, center+60,41,10,Justification::centred,false);
+        g.drawText(String(canvasSplit->getDisplayBufferMean(chan)), 5, center+60,41,10,Justification::centred,false);
 
         if (x > 0)
         {

Plugins/LfpDisplayNode/LfpDisplayCanvas.cpp

@@ -1548,7 +1548,7 @@ uint16 LfpDisplaySplitter::getChannelStreamId(int channel)
     return processor->getContinuousChannel(channel)->getStreamId();
 }
 
-float LfpDisplaySplitter::getMean(int chan)
+float LfpDisplaySplitter::getScreenBufferMean(int chan)
 {
     float total = 0.0f;
     float numPts = 0;
@@ -1566,16 +1566,51 @@ float LfpDisplaySplitter::getMean(int chan)
     return total / numPts;
 }
 
+float LfpDisplaySplitter::getDisplayBufferMean(int chan)
+{
+    float total = 0.0f;
+    float numPts = 0;
+
+    float sample = 0.0f;
+
+    // use 0.1s of sample to compute Mean and Std
+    float totalPoints = 0.1 * sampleRate;
+
+    for (int samp = displayBufferIndex[chan] - totalPoints; samp < displayBufferIndex[chan]; samp += 1)
+    {
+        if (samp >= 0) // read the beginning of the buffer
+            sample = *displayBuffer->getReadPointer(chan, samp);
+        else // read the end of the buffer if negative index
+            sample = *displayBuffer->getReadPointer(chan, displayBuffer->getNumSamples() - samp);
+
+        total += sample;
+        numPts++;
+    }
+
+    //std::cout << sample << std::endl;
+
+    return total / numPts;
+}
+
 float LfpDisplaySplitter::getStd(int chan)
 {
     float std = 0.0f;
+    float sample = 0.0f;
 
-    float mean = getMean(chan);
+    float mean = getDisplayBufferMean(chan);
     float numPts = 1;
 
-    for (int samp = 0; samp < (lfpDisplay->getWidth() - leftmargin); samp += 10)
+    // use 0.1s of sample to compute Mean and Std
+    float totalPoints = 0.1 * sampleRate;
+
+    for (int samp = displayBufferIndex[chan] - totalPoints; samp < displayBufferIndex[chan]; samp += 1)
     {
-        std += pow((*screenBufferMean->getReadPointer(chan, samp) - mean),2);
+        if (samp >= 0) // read the beginning of the buffer
+            sample = *displayBuffer->getReadPointer(chan, samp);
+        else // read the end of the buffer if negative index
+            sample = *displayBuffer->getReadPointer(chan, displayBuffer->getNumSamples() - samp);
+
+        std += pow((sample - mean),2);
         numPts++;
     }
 

Plugins/LfpDisplayNode/LfpDisplayCanvas.h

@@ -263,8 +263,11 @@ class LfpDisplaySplitter : public Component,
     /** Gets the event channel state for a particular sample */
     const float getEventState(int samp);
 
-    /** Returns the mean of a given channel */
-    float getMean(int chan);
+    /** Returns the mean of a given channel, computed from the screen buffer */
+    float getScreenBufferMean(int chan);
+
+    /** Returns the mean of a given channel, computed from the display buffer */
+    float getDisplayBufferMean(int chan);
 
     /** Returns the standard deviation of a given channnel*/
     float getStd(int chan);