comparison Source/Mappings/MRPMapping.cpp @ 0:3580ffe87dc8

First commit of TouchKeys public pre-release.

+/*
+  TouchKeys: multi-touch musical keyboard control software
+  Copyright (c) 2013 Andrew McPherson
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+ 
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ 
+  =====================================================================
+
+  MRPMapping.cpp: mapping class for magnetic resonator piano using continuous
+  key position.
+*/
+
+#include "MRPMapping.h"
+#include <vector>
+
+// Class constants
+// Useful constants for mapping MRP messages
+const int MRPMapping::kMIDINoteOnMessage = 0x90;
+const int MRPMapping::kDefaultMIDIChannel = 15;
+const float MRPMapping::kDefaultAftertouchScaler = 100.0;
+
+// Parameters for vibrato detection and mapping
+const key_velocity MRPMapping::kVibratoVelocityThreshold = scale_key_velocity(2.0);
+const timestamp_diff_type MRPMapping::kVibratoMinimumPeakSpacing = microseconds_to_timestamp(60000);
+const timestamp_diff_type MRPMapping::kVibratoTimeout = microseconds_to_timestamp(500000);
+const int MRPMapping::kVibratoMinimumOscillations = 4;
+const float MRPMapping::kVibratoRateScaler = 0.005;
+
+// Main constructor takes references/pointers from objects which keep track
+// of touch location, continuous key position and the state detected from that
+// position. The PianoKeyboard object is strictly required as it gives access to
+// Scheduler and OSC methods. The others are optional since any given system may
+// contain only one of continuous key position or touch sensitivity
+MRPMapping::MRPMapping(PianoKeyboard &keyboard, MappingFactory *factory, int noteNumber, Node<KeyTouchFrame>* touchBuffer,
+                     Node<key_position>* positionBuffer, KeyPositionTracker* positionTracker)
+: Mapping(keyboard, factory, noteNumber, touchBuffer, positionBuffer, positionTracker),
+  noteIsOn_(false), lastIntensity_(missing_value<float>::missing()),
+  lastBrightness_(missing_value<float>::missing()), lastPitch_(missing_value<float>::missing()),
+  lastHarmonic_(missing_value<float>::missing()),
+  shouldLookForPitchBends_(true), rawVelocity_(kMRPMappingVelocityBufferLength),
+  filteredVelocity_(kMRPMappingVelocityBufferLength, rawVelocity_), lastCalculatedVelocityIndex_(0),
+  vibratoActive_(false), vibratoVelocityPeakCount_(0), vibratoLastPeakTimestamp_(missing_value<timestamp_type>::missing())
+{
+    setAftertouchSensitivity(1.0);
+    
+    // Initialize the filter coefficients for filtered key velocity (used for vibrato detection)
+    std::vector<double> bCoeffs, aCoeffs;
+    designSecondOrderLowpass(bCoeffs, aCoeffs, 15.0, 0.707, 1000.0);
+    std::vector<float> bCf(bCoeffs.begin(), bCoeffs.end()), aCf(aCoeffs.begin(), aCoeffs.end());
+    filteredVelocity_.setCoefficients(bCf, aCf);
+}
+
+// Copy constructor
+/*MRPMapping::MRPMapping(MRPMapping const& obj)
+: Mapping(obj), lastIntensity_(obj.lastIntensity_), lastBrightness_(obj.lastBrightness_),
+aftertouchScaler_(obj.aftertouchScaler_), noteIsOn_(obj.noteIsOn_), lastPitch_(obj.lastPitch_),
+lastHarmonic_(obj.lastHarmonic_),
+shouldLookForPitchBends_(obj.shouldLookForPitchBends_), activePitchBends_(obj.activePitchBends_),
+rawVelocity_(obj.rawVelocity_), filteredVelocity_(obj.filteredVelocity_),
+lastCalculatedVelocityIndex_(obj.lastCalculatedVelocityIndex_), vibratoActive_(obj.vibratoActive_),
+vibratoVelocityPeakCount_(obj.vibratoVelocityPeakCount_), vibratoLastPeakTimestamp_(obj.vibratoLastPeakTimestamp_) {
+
+}*/
+
+MRPMapping::~MRPMapping() {
+    //std::cerr << "~MRPMapping(): " << this << std::endl;
+    
+    try {
+        disengage();
+    }
+    catch(...) {
+        std::cerr << "~MRPMapping(): exception during disengage()\n";
+    }
+    
+    //std::cerr << "~MRPMapping(): done\n";
+}
+
+// Turn off mapping of data. Remove our callback from the scheduler
+void MRPMapping::disengage() {
+    Mapping::disengage();
+    if(noteIsOn_) {
+        int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/midi",
+                              "iii", (int)(kMIDINoteOnMessage + kDefaultMIDIChannel), (int)newNoteNumber, (int)0, LO_ARGS_END);
+       // if(!touchBuffer_->empty())
+       //     keyboard_.testLog_ << touchBuffer_->latestTimestamp() << " /mrp/midi iii " << (kMIDINoteOnMessage + kDefaultMIDIChannel) << " " << newNoteNumber << " " << 0 << endl;
+        
+        // Reset qualities
+        lastPitch_ = lastHarmonic_ = lastBrightness_ = lastIntensity_ = missing_value<float>::missing();
+    }
+    noteIsOn_ = false;
+    shouldLookForPitchBends_ = true;
+}
+
+// Reset state back to defaults
+void MRPMapping::reset() {
+    Mapping::reset();
+    noteIsOn_ = false;
+    shouldLookForPitchBends_ = true;
+}
+
+// Set the aftertouch sensitivity on continuous key position
+// 0 means no aftertouch, 1 means default sensitivity, upward
+// from there
+void MRPMapping::setAftertouchSensitivity(float sensitivity) {
+    if(sensitivity <= 0)
+        aftertouchScaler_ = 0;
+    else
+        aftertouchScaler_ = kDefaultAftertouchScaler * sensitivity;
+}
+
+// This is called by another MRPMapping when it finds a pitch bend starting.
+// Add the sending note to our list of bends, with the sending note marked
+// as controlling the bend
+void MRPMapping::enablePitchBend(int toNote, Node<key_position>* toPositionBuffer,
+                                KeyPositionTracker *toPositionTracker) {
+    if(toPositionBuffer == 0 || toPositionTracker == 0)
+        return;
+    
+    std::cout << "enablePitchBend(): this note = " << noteNumber_ << " note = " << toNote << " posBuf = " << toPositionBuffer << " posTrack = " << toPositionTracker << "\n";
+    PitchBend newBend = {toNote, true, false, toPositionBuffer, toPositionTracker};
+    activePitchBends_.push_back(newBend);
+}
+
+// Trigger method. This receives updates from the TouchKey data or from state changes in
+// the continuous key position (KeyPositionTracker). It will potentially change the scheduled
+// behavior of future mapping calls, but the actual OSC messages should be transmitted in a different
+// thread.
+void MRPMapping::triggerReceived(TriggerSource* who, timestamp_type timestamp) {
+    if(who == 0)
+        return;
+    if(who == positionTracker_) {
+        // The state of the key (based on continuous position) just changed.
+        // Might want to alter our mapping strategy.
+    }
+    else if(who == touchBuffer_) {
+        // TouchKey data is available
+    }
+}
+
+// Mapping method. This actually does the real work of sending OSC data in response to the
+// latest information from the touch sensors or continuous key angle
+timestamp_type MRPMapping::performMapping() {
+    if(!engaged_)
+        return 0;
+    
+    timestamp_type currentTimestamp = keyboard_.schedulerCurrentTimestamp();
+    float intensity = 0;
+    float brightness = 0;
+    float pitch = 0;
+    float harmonic = 0;
+
+    // Calculate the output features as a function of input sensor data
+    if(positionBuffer_ == 0) {
+        // No buffer -> all 0
+    }
+    else if(positionBuffer_->empty()) {
+        // No samples -> all 0
+    }
+    else {
+        // TODO: IIR filter on the position data before mapping it
+        key_position latestPosition = positionBuffer_->latest();
+        int trackerState = kPositionTrackerStateUnknown;
+        if(positionTracker_ != 0)
+            trackerState = positionTracker_->currentState();
+        
+        // Get the latest velocity measurements
+        key_velocity latestVelocity = updateVelocityMeasurements();
+        
+        // Every time we enter a state of PartialPress, check whether this key
+        // is part of a multi-key pitch bend gesture with another key that's already
+        // down. Only do this once, though, since keys that go down after we enter
+        // PartialPress state are not part of such a gesture.
+        if(shouldLookForPitchBends_) {
+            if(trackerState == kPositionTrackerStatePartialPressAwaitingMax ||
+               trackerState == kPositionTrackerStatePartialPressFoundMax) {
+                // Look for a pitch bend gesture by searching for neighboring
+                // keys which are in the Down state and reached that state before
+                // this one reached PartialPress state.
+                for(int neighborNote = noteNumber_ - 2; neighborNote < noteNumber_; neighborNote++) {
+                    // If one of the lower keys is in the Down state, then this note should bend it up
+                    MRPMapping *neighborMapper = dynamic_cast<MRPMapping*>(keyboard_.mapping(neighborNote));
+                    if(neighborMapper == 0)
+                        continue;
+                    if(neighborMapper->positionTracker_ != 0) {
+                        int neighborState = neighborMapper->positionTracker_->currentState();
+                        if(neighborState == kPositionTrackerStateDown) {
+                            // Here we've found a neighboring note in the Down state. But did it precede our transition?
+                            timestamp_type timeOfDownTransition = neighborMapper->positionTracker_->latestTimestamp();
+                            timestamp_type timeOfOurPartialActivation = findTimestampOfPartialPress();
+                            
+                            cout << "Found key " << neighborNote << " in Down state\n";
+                            
+                            if(!missing_value<timestamp_type>::isMissing(timeOfOurPartialActivation)) {
+                                if(timeOfOurPartialActivation > timeOfDownTransition) {
+                                    // The neighbor note went down before us; pitch bend should engage
+                                    cout << "Found pitch bend: " << noteNumber_ << " to " << neighborNote << endl;
+                                    
+                                    // Insert the details for the neighboring note into our buffer. The bend
+                                    // is controlled by our own key, and the target is the neighbor note.
+                                    PitchBend newBend = {neighborNote, false, false, neighborMapper->positionBuffer_,
+                                        neighborMapper->positionTracker_};
+                                    activePitchBends_.push_back(newBend);
+                                
+                                    // Tell the other note to bend its pitch based on our position
+                                    neighborMapper->enablePitchBend(noteNumber_, positionBuffer_, positionTracker_);
+                                }
+                            }
+                        }
+                    }
+                }
+                for(int neighborNote = noteNumber_ + 1; neighborNote < noteNumber_ + 3; neighborNote++) {
+                    // If one of the upper keys is in the Down state, then this note should bend it down
+                    MRPMapping *neighborMapper = dynamic_cast<MRPMapping*>(keyboard_.mapping(neighborNote));
+                    if(neighborMapper == 0)
+                        continue;
+                    if(neighborMapper->positionTracker_ != 0) {
+                        int neighborState = neighborMapper->positionTracker_->currentState();
+                        if(neighborState == kPositionTrackerStateDown) {
+                            // Here we've found a neighboring note in the Down state. But did it precede our transition?
+                            timestamp_type timeOfDownTransition = neighborMapper->positionTracker_->latestTimestamp();
+                            timestamp_type timeOfOurPartialActivation = findTimestampOfPartialPress();
+                            
+                            cout << "Found key " << neighborNote << " in Down state\n";
+                            
+                            if(!missing_value<timestamp_type>::isMissing(timeOfOurPartialActivation)) {
+                                if(timeOfOurPartialActivation > timeOfDownTransition) {
+                                    // The neighbor note went down before us; pitch bend should engage
+                                    cout << "Found pitch bend: " << noteNumber_ << " to " << neighborNote << endl;
+                                    
+                                    // Insert the details for the neighboring note into our buffer. The bend
+                                    // is controlled by our own key, and the target is the neighbor note.
+                                    PitchBend newBend = {neighborNote, false, false, neighborMapper->positionBuffer_,
+                                        neighborMapper->positionTracker_};
+                                    activePitchBends_.push_back(newBend);
+                                    
+                                    // Tell the other note to bend its pitch based on our position
+                                    neighborMapper->enablePitchBend(noteNumber_, positionBuffer_, positionTracker_);
+                                }
+                            }
+                        }
+                    }
+                }
+                
+                shouldLookForPitchBends_ = false;
+            }
+        }
+        
+        if(trackerState == kPositionTrackerStatePartialPressAwaitingMax ||
+           trackerState == kPositionTrackerStatePartialPressFoundMax) {
+            // Look for active vibrato gestures which are defined as oscillating
+            // motion in the key velocity. They could conceivably occur at a variety
+            // of raw key positions, as long as the key is not yet down
+            
+            if(missing_value<timestamp_type>::isMissing(vibratoLastPeakTimestamp_))
+                vibratoLastPeakTimestamp_ = currentTimestamp;
+            
+            if(vibratoVelocityPeakCount_ % 2 == 0) {
+                if(latestVelocity > kVibratoVelocityThreshold && currentTimestamp - vibratoLastPeakTimestamp_ > kVibratoMinimumPeakSpacing) {
+                    std::cout << "Vibrato count = " << vibratoVelocityPeakCount_ << std::endl;
+                    vibratoVelocityPeakCount_++;
+                    vibratoLastPeakTimestamp_ = currentTimestamp;
+                }
+            }
+            else {
+                if(latestVelocity < -kVibratoVelocityThreshold && currentTimestamp - vibratoLastPeakTimestamp_ > kVibratoMinimumPeakSpacing) {
+                    std::cout << "Vibrato count = " << vibratoVelocityPeakCount_ << std::endl;
+                    vibratoVelocityPeakCount_++;
+                    vibratoLastPeakTimestamp_ = currentTimestamp;
+                }
+            }
+            
+            if(vibratoVelocityPeakCount_ >= kVibratoMinimumOscillations) {
+                vibratoActive_ = true;
+            }
+            
+            
+            if(vibratoActive_) {
+                // Update the harmonic parameter, which increases linearly with the absolute
+                // value of velocity. The value will accumulate over the course of a vibrato
+                // gesture and retain its value when the vibrato finishes. It reverts to minimum
+                // when the note finishes.
+                if(missing_value<float>::isMissing(lastHarmonic_))
+                    lastHarmonic_ = 0.0;
+                harmonic = lastHarmonic_ + fabsf(latestVelocity) * kVibratoRateScaler;
+                std::cout << "harmonic = " << harmonic << std::endl;
+                
+                // Check whether the current vibrato has timed out
+                if(currentTimestamp - vibratoLastPeakTimestamp_ > kVibratoTimeout) {
+                    std::cout << "Vibrato timed out\n";
+                    vibratoActive_ = false;
+                    vibratoVelocityPeakCount_ = 0;
+                    vibratoLastPeakTimestamp_ = currentTimestamp;
+                }
+            }
+        }
+        else {
+            // Vibrato can't be active in these states
+            //std::cout << "Vibrato finished from state change\n";
+            vibratoActive_ = false;
+            vibratoVelocityPeakCount_ = 0;
+            vibratoLastPeakTimestamp_ = currentTimestamp;
+        }
+        
+        if(trackerState != kPositionTrackerStateReleaseFinished) {
+            // For all active states except post-release, calculate
+            // Intensity and Brightness parameters based on key position
+            
+            if(latestPosition > 1.0) {
+                intensity = 1.0;
+                brightness = (latestPosition - 1.0) * aftertouchScaler_;
+            }
+            else if(latestPosition < 0.0) {
+                intensity = 0.0;
+                brightness = 0.0;
+            }
+            else {
+                intensity = latestPosition;
+                brightness = 0.0;
+            }
+            
+            if(!activePitchBends_.empty()) {
+                // Look for active multi-key pitch bend gestures
+                std::vector<PitchBend>::iterator it = activePitchBends_.begin();
+                pitch = 0.0;
+                
+                for(it = activePitchBends_.begin(); it != activePitchBends_.end(); it++) {
+                    PitchBend& bend(*it);
+
+                    if(bend.isControllingBend) {
+                        // First find out of the bending key is still in a PartialPress state
+                        // If not, remove it and move on
+                        if((bend.positionTracker->currentState() != kPositionTrackerStatePartialPressAwaitingMax &&
+                           bend.positionTracker->currentState() != kPositionTrackerStatePartialPressFoundMax)
+                           || !bend.positionTracker->engaged()) {
+                            cout << "Removing bend from note " << bend.note << endl;
+                            bend.isFinished = true;
+                            continue;
+                        }
+                        
+                        // This is the case where the other note is controlling our pitch
+                        if(bend.positionBuffer->empty()) {
+                            continue;
+                        }
+                        
+                        float noteDifference = (float)(bend.note - noteNumber_);
+                        key_position latestBenderPosition = bend.positionBuffer->latest();
+                        
+                        // Key position at 0 = 0 pitch bend; key position at max = most pitch bend
+                        float bendAmount = key_position_to_float(latestBenderPosition - kPianoKeyDefaultIdlePositionThreshold*2) /
+                                                key_position_to_float(1.0 - kPianoKeyDefaultIdlePositionThreshold*2);
+                        if(bendAmount < 0)
+                            bendAmount = 0;
+                        pitch += noteDifference * bendAmount;
+                    }
+                    else {
+                        // This is the case where we're controlling the other note's pitch. Our own
+                        // pitch is the inverse of what we're sending to the neighboring note.
+                        // Compared to the above case, we know a few things since we're using our own
+                        // position: the buffer isn't empty and the tracker is engaged.
+                        
+                        if(trackerState != kPositionTrackerStatePartialPressAwaitingMax &&
+                           trackerState != kPositionTrackerStatePartialPressFoundMax) {
+                            cout << "Removing our bend on note " << bend.note << endl;
+                            bend.isFinished = true;
+                            continue;
+                        }
+  
+                        float noteDifference = (float)(bend.note - noteNumber_);
+                        
+                        // Key position at 0 = 0 pitch bend; key position at max = most pitch bend
+                        float bendAmount = key_position_to_float(latestPosition - kPianoKeyDefaultIdlePositionThreshold*2) /
+                                            key_position_to_float(1.0 - kPianoKeyDefaultIdlePositionThreshold*2);
+                        if(bendAmount < 0)
+                            bendAmount = 0;
+                        pitch += noteDifference * (1.0 - bendAmount);
+                    }
+                }
+                
+                // Now reiterate to remove any of them that have finished
+                it = activePitchBends_.begin();
+                
+                while(it != activePitchBends_.end()) {
+                    if(it->isFinished) {
+                        // Go back to beginning and look again after erasing each one
+                        // This isn't very efficient but there will never be more than 4 elements anyway
+                        activePitchBends_.erase(it);
+                        it = activePitchBends_.begin();
+                    }
+                    else
+                        it++;
+                }
+                
+                std::cout << "pitch = " << pitch << std::endl;
+            }
+            else
+                pitch = 0.0;
+        }
+        else {
+            intensity = 0.0;
+            brightness = 0.0;
+            if(noteIsOn_) {
+                        int newNoteNumber = noteNumber_;
+                //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+                keyboard_.sendMessage("/mrp/midi",
+                                      "iii", (int)(kMIDINoteOnMessage + kDefaultMIDIChannel), (int)newNoteNumber, (int)0, LO_ARGS_END);
+                //keyboard_.testLog_ << currentTimestamp << " /mrp/midi iii " << (kMIDINoteOnMessage + kDefaultMIDIChannel) << " " << newNoteNumber << " " << 0 << endl;
+            }
+            noteIsOn_ = false;
+            shouldLookForPitchBends_ = true;
+        }
+    }
+    
+    // TODO: TouchKeys mapping
+    
+    // Send OSC message with these parameters unless they are unchanged from before
+    if(!noteIsOn_ && intensity > 0.0) {
+                int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/midi",
+                              "iii", (int)(kMIDINoteOnMessage + kDefaultMIDIChannel), (int)newNoteNumber, (int)127, LO_ARGS_END);
+        //keyboard_.testLog_ << currentTimestamp << " /mrp/midi iii " << (kMIDINoteOnMessage + kDefaultMIDIChannel) << " " << newNoteNumber << " " << 127 << endl;
+        noteIsOn_ = true;
+    }
+    
+    // Set key LED color according to key parameters
+    // Partial press --> green of varying intensity
+    // Aftertouch (brightness) --> green moving to red depending on brightness parameter
+    // Pitch bend --> note bends toward blue as pitch value departs from center
+    // Harmonic glissando --> cycle through hues with whitish tint (lower saturation)
+    if(intensity != lastIntensity_ || brightness != lastBrightness_ || pitch != lastPitch_ || harmonic != lastHarmonic_) {
+        if(harmonic != 0.0) {
+            float hue = fmodf(harmonic, 1.0);
+            keyboard_.setKeyLEDColorHSV(noteNumber_, hue, 0.25, 0.5);
+        }
+        else if(intensity >= 1.0) {
+            if(pitch != 0.0)
+                keyboard_.setKeyLEDColorHSV(noteNumber_, 0.33 + 0.33 * fabsf(pitch) - (brightness * 0.2), 1.0, intensity);
+            else
+                keyboard_.setKeyLEDColorHSV(noteNumber_, 0.33 - (brightness * 0.2), 1.0, 1.0);
+        }
+        else {
+            if(pitch != 0.0)
+                keyboard_.setKeyLEDColorHSV(noteNumber_, 0.33 + 0.33 * fabsf(pitch), 1.0, intensity);
+            else
+                keyboard_.setKeyLEDColorHSV(noteNumber_, 0.33, 1.0, intensity);
+        }
+    }
+        
+    if(intensity != lastIntensity_) {
+                int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/quality/intensity",
+                              "iif", (int)kDefaultMIDIChannel, (int)newNoteNumber, (float)intensity, LO_ARGS_END);
+        //keyboard_.testLog_ << currentTimestamp << " /mrp/quality/intensity iif " << kDefaultMIDIChannel << " " << newNoteNumber << " " << intensity << endl;
+    }
+    if(brightness != lastBrightness_) {
+                int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/quality/brightness",
+                              "iif", (int)kDefaultMIDIChannel, (int)newNoteNumber, (float)brightness, LO_ARGS_END);
+        //keyboard_.testLog_ << currentTimestamp << " /mrp/quality/brightness iif " << kDefaultMIDIChannel << " " << newNoteNumber << " " << brightness << endl;
+    }
+    if(pitch != lastPitch_) {
+                int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/quality/pitch",
+                              "iif", (int)kDefaultMIDIChannel, (int)newNoteNumber, (float)pitch, LO_ARGS_END);
+        //keyboard_.testLog_ << currentTimestamp << " /mrp/quality/pitch iif " << kDefaultMIDIChannel << " " << newNoteNumber << " " << pitch << endl;
+    }
+    if(harmonic != lastHarmonic_) {
+        int newNoteNumber = noteNumber_;
+        //int newNoteNumber = ((noteNumber_ - 21) * 25)%88 + 21;
+        keyboard_.sendMessage("/mrp/quality/harmonic",
+                              "iif", (int)kDefaultMIDIChannel, (int)newNoteNumber, (float)harmonic, LO_ARGS_END);
+        //keyboard_.testLog_ << currentTimestamp << " /mrp/quality/harmonic iif " << kDefaultMIDIChannel << " " << newNoteNumber << " " << harmonic << endl;
+    }
+    
+    lastIntensity_ = intensity;
+    lastBrightness_ = brightness;
+    lastPitch_ = pitch;
+    lastHarmonic_ = harmonic;
+    
+    // Register for the next update by returning its timestamp
+    nextScheduledTimestamp_ = currentTimestamp + updateInterval_;
+    return nextScheduledTimestamp_;
+}
+
+// Helper function that brings the velocity buffer up to date with the latest
+// samples. Velocity is not updated on every new position sample since it's not
+// efficient to run that many triggers all the time. Instead, it's brought up to
+// date on an as-needed basis during performMapping().
+key_velocity MRPMapping::updateVelocityMeasurements() {
+    positionBuffer_->lock_mutex();
+    
+    // Need at least 2 samples to calculate velocity (first difference)
+    if(positionBuffer_->size() < 2) {
+        positionBuffer_->unlock_mutex();
+        return missing_value<key_velocity>::missing();
+    }
+    
+    if(lastCalculatedVelocityIndex_ < positionBuffer_->beginIndex() + 1) {
+        // Fell off the beginning of the position buffer. Reset calculations.
+        filteredVelocity_.clear();
+        rawVelocity_.clear();
+        lastCalculatedVelocityIndex_ = positionBuffer_->beginIndex() + 1;
+    }
+    
+    while(lastCalculatedVelocityIndex_ < positionBuffer_->endIndex()) {
+        // Calculate the velocity and add to buffer
+        key_position diffPosition = (*positionBuffer_)[lastCalculatedVelocityIndex_] - (*positionBuffer_)[lastCalculatedVelocityIndex_ - 1];
+        timestamp_diff_type diffTimestamp = positionBuffer_->timestampAt(lastCalculatedVelocityIndex_) - positionBuffer_->timestampAt(lastCalculatedVelocityIndex_ - 1);
+        key_velocity vel;
+        
+        if(diffTimestamp != 0)
+            vel = calculate_key_velocity(diffPosition, diffTimestamp);
+        else
+            vel = 0; // Bad measurement: replace with 0 so as not to mess up IIR calculations
+        
+        // Add the raw velocity to the buffer
+        rawVelocity_.insert(vel, positionBuffer_->timestampAt(lastCalculatedVelocityIndex_));
+        lastCalculatedVelocityIndex_++;
+    }
+    
+    positionBuffer_->unlock_mutex();
+    
+    // Bring the filtered velocity up to date
+    key_velocity filteredVel = filteredVelocity_.calculate();
+    //std::cout << "Key " << noteNumber_ << " velocity " << filteredVel << std::endl;
+    return filteredVel;
+}
+
+// Helper function that locates the timestamp at which this key entered the
+// PartialPress (i.e. first non-idle) state. Returns missing value if the
+// state can't be located.
+timestamp_type MRPMapping::findTimestampOfPartialPress() {
+    if(positionTracker_ == 0)
+        return missing_value<timestamp_type>::missing();
+    if(positionTracker_->empty())
+        return missing_value<timestamp_type>::missing();
+    //Node<int>::reverse_iterator it = positionTracker_->rbegin();
+    Node<int>::size_type index = positionTracker_->endIndex() - 1;
+    bool foundPartialPressState = false;
+    timestamp_type earliestPartialPressTimestamp;
+
+    // Search backwards from present
+    while(index >= positionTracker_->beginIndex()/*it != positionTracker_->rend()*/) {
+        if((*positionTracker_)[index].state == kPositionTrackerStatePartialPressAwaitingMax ||
+           (*positionTracker_)[index].state == kPositionTrackerStatePartialPressFoundMax) {
+            cout << "index " << index << " state " << (*positionTracker_)[index].state << endl;
+            foundPartialPressState = true;
+            earliestPartialPressTimestamp = positionTracker_->timestampAt(index);
+        }
+        else {
+            // This state is not a PartialPress state. Two cases: either
+            // we haven't yet encountered a partial press or we have found
+            // a state before the partial press, in which case the previous
+            // state we found was the first.
+                        cout << "index " << index << " state " << (*positionTracker_)[index].state << endl;
+            if(foundPartialPressState) {
+                return earliestPartialPressTimestamp;
+            }
+        }
+        
+        // Step backwards one sample, but stop if we hit the beginning index
+        if(index == 0)
+            break;
+        index--;
+    }
+    
+    if(foundPartialPressState)
+        return earliestPartialPressTimestamp;
+    
+    // Didn't find anything if we get here
+    return missing_value<timestamp_type>::missing();
+}