Changing tempos support

CMakeLists.txt

@@ -712,6 +712,7 @@ add_library(mixxx-lib STATIC EXCLUDE_FROM_ALL
   src/track/beatmap.cpp
   src/track/beats.cpp
   src/track/beatutils.cpp
+  src/track/beatstats.cpp
   src/track/bpm.cpp
   src/track/cue.cpp
   src/track/cueinfo.cpp

build/depends.py

@@ -1221,6 +1221,7 @@ def sources(self, build):
                    "src/track/beatgrid.cpp",
                    "src/track/beatmap.cpp",
                    "src/track/beatutils.cpp",
+                   "src/track/beatstats.cpp",
                    "src/track/beats.cpp",
                    "src/track/bpm.cpp",
                    "src/track/cue.cpp",

src/track/beatfactory.cpp

@@ -119,7 +119,8 @@ mixxx::BeatsPointer BeatFactory::makePreferredBeats(const Track& track,
         pGrid->setSubVersion(subVersion);
         return mixxx::BeatsPointer(pGrid, &BeatFactory::deleteBeats);
     } else if (version == BEAT_MAP_VERSION) {
-        mixxx::BeatMap* pBeatMap = new mixxx::BeatMap(track, iSampleRate, beats);
+        auto fixedBeats = BeatUtils::FixBeatmap(beats, iSampleRate, iMinBpm, iMaxBpm);
+        mixxx::BeatMap* pBeatMap = new mixxx::BeatMap(track, iSampleRate, fixedBeats);
         pBeatMap->setSubVersion(subVersion);
         return mixxx::BeatsPointer(pBeatMap, &BeatFactory::deleteBeats);
     } else {

src/track/beatstats.cpp

@@ -0,0 +1,38 @@
+#include <QList>
+#include <QMap>
+
+#include <algorithm>
+#include <cmath>
+
+#include "track/beatstats.h"
+#include "util/fpclassify.h"
+
+void MovingMedian::update(double newValue, double oldValue) {
+    auto insertPosition = std::lower_bound(m_sortedValues.begin(), m_sortedValues.end(), newValue);
+    m_sortedValues.insert(insertPosition, newValue);
+    if (!util_isnan(oldValue)) {
+        m_sortedValues.removeAt(m_sortedValues.indexOf(oldValue));
+    }
+}
+
+double MovingMedian::compute() {
+    return BeatStatistics::median(m_sortedValues);
+}
+
+double BeatStatistics::median(QList<double> sortedItems) {
+    if (sortedItems.empty()) {
+        return 0.0;
+    }
+    // When there are an even number of elements, the sample median is the mean
+    // of the middle 2 elements.
+    if (sortedItems.size() % 2 == 0) {
+        int item_position = sortedItems.size() / 2;
+        double item_value1 = sortedItems.at(item_position - 1);
+        double item_value2 = sortedItems.at(item_position);
+        return (item_value1 + item_value2) / 2.0;
+    }
+    // When there are an odd number of elements, find the {(n+1)/2}th item in
+    // the sorted list.
+    int item_position = (sortedItems.size() + 1) / 2;
+    return sortedItems.at(item_position - 1);
+}

src/track/beatstats.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <QQueue>
+#include "util/assert.h"
+
+/// These classes are used to compute statistics descriptors
+/// of a series of tempo values and are called from beatutils
+
+class WindowedStatistics {
+
+    public:
+
+        WindowedStatistics(int period) {
+            DEBUG_ASSERT(period > 0);
+            m_period = period;
+        }
+        virtual ~WindowedStatistics() = default;
+
+        double operator()(double newValue) {
+            double oldValue = updateWindow(newValue);
+            update(newValue, oldValue);
+            return compute();
+        }
+        double operator()(void) {
+            return compute();
+        }
+        int lag() {
+            // expected latency
+            return (m_window.size() - 1)/2;
+        }
+
+    private:
+
+        double updateWindow(double newValue) {
+                m_window.enqueue(newValue);
+            if (m_window.count() > m_period) {
+                return m_window.dequeue();
+            } else {
+                return std::nan("");
+            }
+        }
+        virtual double compute() = 0;
+        virtual void update(double newValue, double oldValue) = 0;
+        QQueue<double> m_window;
+        int m_period;
+};
+
+class BeatStatistics {
+  public:
+    static double median(QList<double> sortedItems);
+};
+
+class MovingMedian : public WindowedStatistics {
+    QList<double> m_sortedValues;
+    void update(double, double) override;
+    double compute() override;
+    public:
+      MovingMedian(int period)
+              : WindowedStatistics(period) {};
+      ~MovingMedian() = default;
+};