PositionScratchCon: fix explicit seeking while scratching, eg. jump t…

…o hotcue adopt the seek position explicitly in order to avoid crazy seek speeds
mixxxdj · Dec 31, 2024 · dff5e6a · dff5e6a
1 parent 65f0d9f
commit dff5e6a
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Showing 3 changed files with 28 additions and 16 deletions.
diff --git a/src/engine/positionscratchcontroller.cpp b/src/engine/positionscratchcontroller.cpp
@@ -76,6 +76,7 @@ constexpr double kThrowThreshold = 2.5;
 // Max velocity we would like to stop in a given time period.
 constexpr double kMaxVelocity = 100;
 // Seconds to stop a throw at the max velocity.
+// TODO make configurable, eg. to customize spinbacks with controllers
 constexpr double kTimeToStop = 1.0;
 
 } // anonymous namespace
@@ -93,6 +94,9 @@ PositionScratchController::PositionScratchController(const QString& group)
           m_isScratching(false),
           m_inertiaEnabled(false),
           m_prevSamplePos(0),
+          // TODO we might as well use FramePos in order to use more convenient
+          // mixxx::audio::kInvalidFramePos, then convert to sample pos on the fly
+          m_seekSamplePos(std::numeric_limits<double>::quiet_NaN()),
           m_samplePosDeltaSum(0),
           m_scratchTargetDelta(0),
           m_scratchStartPos(0),
@@ -102,6 +106,7 @@ PositionScratchController::PositionScratchController(const QString& group)
           m_bufferSize(-1), // ?
           m_dt(1),
           m_callsPerDt(1),
+          m_callsToStop(1), // ?
           m_p(1),
           m_d(1),
           m_f(0.4) {
@@ -123,6 +128,8 @@ void PositionScratchController::slotUpdateFilterParameters(double sampleRate) {
     // lowpass filter
     m_callsPerDt = static_cast<int>(ceil(kDefaultSampleInterval / m_dt));
 
+    m_callsToStop = m_dt / kTimeToStop;
+
     // Tweak PD controller for different latencies
     m_p = 0.3;
     m_d = m_p / -2;
@@ -155,6 +162,22 @@ void PositionScratchController::process(double currentSamplePos,
         slotUpdateFilterParameters(m_pMainSampleRate->get());
     }
 
+    if (!util_isnan(m_seekSamplePos)) {
+        // If we were notified about a sekk, adopt the new position immediately.
+        m_seekSamplePos = std::numeric_limits<double>::quiet_NaN();
+        m_prevSamplePos = currentSamplePos;
+        m_rate = 0;
+        // Reset filters in a way that the system is settled.
+        // Set to the remaining error of a p controller // ??
+        m_samplePosDeltaSum = -(releaseRate / m_p) * m_callsPerDt;
+        m_pVelocityController->reset(-m_samplePosDeltaSum);
+        m_pRateIIFilter->reset(-m_samplePosDeltaSum);
+        m_scratchStartPos = m_pScratchPos->get();
+        m_scratchTargetDelta = 0;
+        m_moveDelay = 0;
+        return;
+    }
+
     double scratchPosition = 0;
     m_mouseSampleTime += m_dt;
     if (m_mouseSampleTime >= kDefaultSampleInterval || !m_isScratching) {
@@ -182,7 +205,7 @@ void PositionScratchController::process(double currentSamplePos,
             // kMaxVelocity * alpha ^ (# callbacks to stop in) = decayThreshold
             // # callbacks = kTimeToStop / m_dt
             // alpha = (decayThreshold / kMaxVelocity) ^ (m_dt / kTimeToStop)
-            const double kExponentialDecay = pow(decayThreshold / kMaxVelocity, m_dt / kTimeToStop);
+            const double kExponentialDecay = pow(decayThreshold / kMaxVelocity, m_callsToStop);
 
             m_rate *= kExponentialDecay;
 

diff --git a/src/engine/positionscratchcontroller.h b/src/engine/positionscratchcontroller.h
@@ -39,14 +39,17 @@ class PositionScratchController : public QObject {
 
   private:
     const QString m_group;
+
     std::unique_ptr<ControlObject> m_pScratchEnable;
     std::unique_ptr<ControlObject> m_pScratchPos;
     std::unique_ptr<ControlProxy> m_pMainSampleRate;
     std::unique_ptr<VelocityController> m_pVelocityController;
     std::unique_ptr<RateIIFilter> m_pRateIIFilter;
+
     bool m_isScratching;
     bool m_inertiaEnabled;
     double m_prevSamplePos;
+    double m_seekSamplePos;
     double m_samplePosDeltaSum;
     double m_scratchTargetDelta;
     double m_scratchStartPos;
@@ -58,6 +61,7 @@ class PositionScratchController : public QObject {
 
     double m_dt;
     double m_callsPerDt;
+    double m_callsToStop;
 
     double m_p;
     double m_d;

diff --git a/src/engine/readaheadmanager.cpp b/src/engine/readaheadmanager.cpp
@@ -283,22 +283,8 @@ double ReadAheadManager::getFilePlaypositionFromLog(
     }
 
     double filePlayposition = 0;
-    bool shouldNotifySeek = false;
     while (m_readAheadLog.size() > 0 && numConsumedSamples > 0) {
         ReadLogEntry& entry = m_readAheadLog.front();
-
-        // Notify EngineControls that we have taken a seek.
-        // Every new entry start with a seek
-        // (Not looping control)
-        if (shouldNotifySeek) {
-            if (m_pRateControl) {
-                const auto seekPosition =
-                        mixxx::audio::FramePos::fromEngineSamplePos(
-                                entry.virtualPlaypositionStart);
-                m_pRateControl->notifySeek(seekPosition);
-            }
-        }
-
         // Advance our idea of the current virtual playposition to this
         // ReadLogEntry's start position.
         filePlayposition = entry.advancePlayposition(&numConsumedSamples);
@@ -307,7 +293,6 @@ double ReadAheadManager::getFilePlaypositionFromLog(
             // This entry is empty now.
             m_readAheadLog.pop_front();
         }
-        shouldNotifySeek = true;
     }
 
     return filePlayposition;