=== modified file 'mixxx/src/analyserwaveform.cpp'
--- mixxx/src/analyserwaveform.cpp	2009-07-14 19:01:34 +0000
+++ mixxx/src/analyserwaveform.cpp	2010-01-31 16:21:56 +0000
@@ -42,6 +42,7 @@
 
     downsample = new QVector<float>(numDownsamples);
     downsampleVector = downsample->data();
+    downsamplePos = 0;
     int i;
 
     // Set the buffer to zero
@@ -55,11 +56,24 @@
 
     qDebug() << "AnalyserWaveform: f " << sampleRate << " samplesPerDownsample: " << samplesPerDownsample << " downsamples " << numDownsamples << " from " << totalSamples;
 
-    m_iStrideLength = samplesPerDownsample*2;
-    m_iCurPos = 0;
-    m_iBufferPos = 0;
-    m_fLMax = -1.0;
-    m_fRMax = -1.0;
+
+    m_iStrideLength = samplesPerDownsample;
+
+    m_PreBufSize = 40; // must be smaller than samplesPerDownsample
+    m_PreBufPos = 0;
+    m_PreBuf = 0;
+
+    float AveragingTimeInSec = 0.01;
+    m_AveragingBufPos = 0;
+    m_AveragingBufSize = round((float) sampleRate * AveragingTimeInSec/m_PreBufSize); // samplerate in 1/Sec
+    m_AveragingBuf.resize(m_AveragingBufSize);
+    // Set the buffer to zero
+    for(int i=0;i<m_AveragingBufSize;i++) {
+        m_AveragingBuf[i] = 0;
+    }
+
+    m_iCurTracksamplePos = 0; // mono samples
+    m_AnalysedTracksamplesPos = 0; // mono samples
 
     m_iStartTime = clock();
 }
@@ -69,34 +83,55 @@
     if(downsample == NULL) {
         return;
     }
+/**
+  When ever m_StrideLenght in samples is elapsed average of AveragingBuf is
+  calculated. AvegagingBuf averages over a period longer than m_StrideLength.
+  This is intentinally although it shouldn't be to long to get a responsive
+  waveform.
+
+  AveragingBuf is updated with PreBuf asynchron to m_StrideLength this means
+  some few values lately added to PreBuf aren't recognized when calculating
+  average over AveragingBuf. This is no big disatvantage since it is only a
+  small part compared to content AveragingBuf and audio signal doesn't change
+  that fast as well.
+
+  PreBuf contains the sum of many samples thus when calculating the sum of
+  AveragingBuf less values have to be summed up. That is the point where this
+  algorithm speeds up calculation. As well as every sub step in for loop is
+  out lay with as simple as possible if conditions that are fast to evaluate. 
+**/
+    // iLen in total samples
+    int len = iLen - iLen%2; // round down to even value 
 
     //qDebug() << "AnalyserWaveform::process() processing " << iLen << " samples";
-    for(int i=0; i<iLen; i+=2) {
-      
-        if(m_iBufferPos >= m_iStrideLength) {
-            //(*downsample)[m_iCurPos] = m_fLMax;
-            *(downsampleVector++) = m_fLMax;
-            m_iCurPos++;
-
-            //(*downsample)[m_iCurPos] = m_fRMax;
-            *(downsampleVector++) = m_fRMax;
-            m_iCurPos++;
-            
-            m_iBufferPos = 0;
-            m_fLMax = -1.0f;
-            m_fRMax = -1.0f;
-        }
-        CSAMPLE sl = fabs(pIn[i]);
-        CSAMPLE sr = fabs(pIn[i+1]);
-
-        if(m_iBufferPos <= 20) {
-            if(sl > m_fLMax)
-                m_fLMax = sl;
-            if(sr > m_fRMax)
-                m_fRMax = sr;
-        }
-	
-        m_iBufferPos += 2;
+    for(int i=0; i<len; i+=2) {
+        m_PreBuf += pIn[i] * pIn[i];
+        m_PreBuf += pIn[i+1] * pIn[i+1];
+        m_PreBufPos++;
+        if(m_PreBufPos >= m_PreBufSize) {
+            m_AveragingBuf[m_AveragingBufPos++] = m_PreBuf;
+            m_PreBufPos = 0;
+            m_PreBuf = 0;
+            if(m_AveragingBufPos >= m_AveragingBufSize) {
+                m_AveragingBufPos = 0;
+            }
+        }
+
+        m_iCurTracksamplePos++;
+        if(m_iCurTracksamplePos >= m_AnalysedTracksamplesPos+m_iStrideLength) {
+            m_AnalysedTracksamplesPos += m_iStrideLength;
+            float temp = 0;
+            for(int j = 0; j < m_AveragingBufSize;j++) {
+                temp += m_AveragingBuf[j];
+            }
+            temp = sqrt(temp/(m_PreBufSize*m_AveragingBufSize)); // consider numbers get large
+
+            if( downsamplePos < downsample->size()) { // checking limits is a must
+              *(downsampleVector++) = temp;
+              *(downsampleVector++) = temp;
+            }
+            downsamplePos += 2;
+        }
     }
 }
 
@@ -104,7 +139,7 @@
     if(downsample == NULL) {
         return;
     }
-
+ 
     downsample = NULL;
     downsampleVector = NULL;
     

=== modified file 'mixxx/src/analyserwaveform.h'
--- mixxx/src/analyserwaveform.h	2009-02-01 21:40:44 +0000
+++ mixxx/src/analyserwaveform.h	2010-01-31 16:03:52 +0000
@@ -12,15 +12,22 @@
 	void finalise(TrackInfoObject* tio);
 
 private:
-	QVector<float> *downsample;
+    QVector<float> *downsample;
     float *downsampleVector;
+    int downsamplePos;
+
+    QVector<float> m_AveragingBuf;
+    int m_AveragingBufPos;
+    int m_AveragingBufSize;
+
+    float m_PreBuf;
+    int m_PreBufPos;
+    int m_PreBufSize;
     
     int m_iStartTime;
     int m_iStrideLength;
-    int m_iCurPos;
-    int m_iBufferPos;
-    float m_fLMax;
-    float m_fRMax;
+    int m_iCurTracksamplePos; // stereo samples
+    int m_AnalysedTracksamplesPos; // sereo samples
 };
 
 #endif