feat(sointu): rewrote sequencer to add support for keyjazzing

sointu.go

@@ -304,6 +304,14 @@ func (s *Song) FirstTrackVoice(track int) int {
 	return ret
 }
 
+func (s *Song) FirstInstrumentVoice(instrument int) int {
+	ret := 0
+	for _, i := range s.Patch.Instruments[:instrument] {
+		ret += i.NumVoices
+	}
+	return ret
+}
+
 func (s *Song) TotalTrackVoices() int {
 	ret := 0
 	for _, t := range s.Tracks {

tracker/keyevent.go

@@ -268,8 +268,15 @@ func (t *Tracker) KeyEvent(e key.Event) bool {
 					return true
 				}
 				if val, ok := noteMap[e.Name]; ok {
-					t.NotePressed(val)
-					return true
+					if _, ok := t.KeyPlaying[e.Name]; !ok {
+						n := getNoteValue(int(t.Octave.Value), val)
+						t.SetCurrentNote(n)
+						trk := t.Cursor.Track
+						start := t.song.FirstTrackVoice(trk)
+						end := start + t.song.Tracks[trk].NumVoices
+						t.KeyPlaying[e.Name] = t.sequencer.Trigger(start, end, n)
+						return true
+					}
 				}
 			}
 		case EditUnits:
@@ -279,10 +286,30 @@ func (t *Tracker) KeyEvent(e key.Event) bool {
 			}
 			if val, ok := unitKeyMap[name]; ok {
 				if e.Modifiers.Contain(key.ModCtrl) {
-					t.AddUnit()
+					t.SetUnit(val)
+					return true
 				}
-				t.SetUnit(val)
-				return true
+			}
+			fallthrough
+		case EditParameters:
+			if val, ok := noteMap[e.Name]; ok {
+				if _, ok := t.KeyPlaying[e.Name]; !ok {
+					note := getNoteValue(int(t.Octave.Value), val)
+					instr := t.CurrentInstrument
+					start := t.song.FirstInstrumentVoice(instr)
+					end := start + t.song.Patch.Instruments[instr].NumVoices
+					t.KeyPlaying[e.Name] = t.sequencer.Trigger(start, end, note)
+					return false
+				}
+			}
+		}
+	}
+	if e.State == key.Release {
+		if f, ok := t.KeyPlaying[e.Name]; ok {
+			f()
+			delete(t.KeyPlaying, e.Name)
+			if t.EditMode == EditTracks && t.Playing && t.getCurrent() == 1 {
+				t.SetCurrentNote(0)
 			}
 		}
 	}
@@ -294,11 +321,6 @@ func (t *Tracker) getCurrent() byte {
 	return t.song.Tracks[t.Cursor.Track].Patterns[t.song.Tracks[t.Cursor.Track].Sequence[t.Cursor.Pattern]][t.Cursor.Row]
 }
 
-// NotePressed handles incoming key presses while in the note column
-func (t *Tracker) NotePressed(val int) {
-	t.SetCurrentNote(getNoteValue(int(t.Octave.Value), val))
-}
-
 // NumberPressed handles incoming presses while in either of the hex number columns
 func (t *Tracker) NumberPressed(iv byte) {
 	val := t.getCurrent()

tracker/run.go

@@ -1,19 +1,20 @@
 package tracker
 
 import (
+	"os"
+
 	"gioui.org/app"
 	"gioui.org/io/key"
 	"gioui.org/io/system"
 	"gioui.org/layout"
 	"gioui.org/op"
-	"os"
 )
 
 func (t *Tracker) Run(w *app.Window) error {
 	var ops op.Ops
 	for {
 		select {
-		case <-t.ticked:
+		case <-t.refresh:
 			w.Invalidate()
 		case e := <-w.Events():
 			switch e := e.(type) {

tracker/sequencer.go

@@ -1,9 +1,7 @@
 package tracker
 
 import (
-	"fmt"
 	"math"
-	"sync"
 	"sync/atomic"
 
 	"github.com/vsariola/sointu"
@@ -20,96 +18,147 @@ const SEQUENCER_MAX_READ_TRIES = 1000
 // iterator. Note that the iterator should be thread safe, as the ReadAudio
 // might be called from another go routine.
 type Sequencer struct {
-	// we use mutex to ensure that voices are not triggered during readaudio or
-	// that the synth is not changed when audio is being read
-	mutex      sync.Mutex
-	synth      sointu.Synth
-	validSynth int32
-	service    sointu.SynthService
-	// this iterator is a bit unconventional in the sense that it might return
-	// hasNext false, but might still return hasNext true in future attempts if
-	// new rows become available.
-	iterator  func() ([]Note, bool)
-	rowTime   int
-	rowLength int
+	validSynth    int32
+	closer        chan struct{}
+	setPatch      chan sointu.Patch
+	setRowLength  chan int
+	noteOn        chan noteOnEvent
+	noteOff       chan uint32
+	synth         sointu.Synth
+	voiceNoteID   []uint32
+	voiceReleased []bool
+	idCounter     uint32
 }
 
-type Note struct {
-	Voice int
-	Note  byte
+type RowNote struct {
+	NumVoices int
+	Note      byte
 }
 
-func NewSequencer(service sointu.SynthService, iterator func() ([]Note, bool)) *Sequencer {
-	return &Sequencer{
-		service:   service,
-		iterator:  iterator,
-		rowLength: math.MaxInt32,
-		rowTime:   math.MaxInt32,
+type noteOnEvent struct {
+	voiceStart int
+	voiceEnd   int
+	note       byte
+	id         uint32
+}
+
+type noteID struct {
+	voice int
+	id    uint32
+}
+
+func NewSequencer(bufferSize int, service sointu.SynthService, context sointu.AudioContext, iterator func([]RowNote) []RowNote) *Sequencer {
+	ret := &Sequencer{
+		closer:        make(chan struct{}),
+		setPatch:      make(chan sointu.Patch, 32),
+		setRowLength:  make(chan int, 32),
+		noteOn:        make(chan noteOnEvent, 32),
+		noteOff:       make(chan uint32, 32),
+		voiceNoteID:   make([]uint32, 32),
+		voiceReleased: make([]bool, 32),
 	}
+	// the iterator is a bit unconventional in the sense that it might return
+	// false to indicate that there is no row available, but might still return
+	// true in future attempts if new rows become available.
+	go ret.loop(bufferSize, service, context, iterator)
+	return ret
 }
 
-func (s *Sequencer) ReadAudio(buffer []float32) (int, error) {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-	totalRendered := 0
-	for i := 0; i < SEQUENCER_MAX_READ_TRIES; i++ {
-		gotRow := true
-		if s.rowTime >= s.rowLength {
-			var row []Note
-			s.mutex.Unlock()
-			row, gotRow = s.iterator()
-			s.mutex.Lock()
-			if gotRow {
-				for _, n := range row {
-					s.doNote(n.Voice, n.Note)
-				}
-				s.rowTime = 0
-			} else {
-				for i := 0; i < 32; i++ {
-					s.doNote(i, 0)
+func (s *Sequencer) loop(bufferSize int, service sointu.SynthService, context sointu.AudioContext, iterator func([]RowNote) []RowNote) {
+	buffer := make([]float32, bufferSize)
+	renderTries := 0
+	audioOut := context.Output()
+	defer audioOut.Close()
+	rowIn := make([]RowNote, 32)
+	rowLength := math.MaxInt32
+	rowTimeRemaining := 0
+	trackNotes := make([]uint32, 32)
+	for {
+		for !s.Enabled() {
+			select {
+			case <-s.closer:
+				return
+			case <-s.noteOn:
+			case <-s.noteOff:
+			case rowLength = <-s.setRowLength:
+			case patch := <-s.setPatch:
+				var err error
+				s.synth, err = service.Compile(patch)
+				if err == nil {
+					s.enable()
+					break
 				}
 			}
 		}
-		rowTimeRemaining := s.rowLength - s.rowTime
-		if !gotRow {
-			rowTimeRemaining = math.MaxInt32
-		}
-		if s.Enabled() {
-			rendered, timeAdvanced, err := s.synth.Render(buffer[totalRendered*2:], rowTimeRemaining)
-			if err != nil {
-				s.Disable()
-			}
-			totalRendered += rendered
-			s.rowTime += timeAdvanced
-		} else {
-			for totalRendered*2 < len(buffer) && rowTimeRemaining > 0 {
-				buffer[totalRendered*2] = 0
-				buffer[totalRendered*2+1] = 0
-				totalRendered++
-				s.rowTime++
-				rowTimeRemaining--
+		released := false
+		for s.Enabled() {
+			select {
+			case <-s.closer:
+				return
+			case n := <-s.noteOn:
+				s.trigger(n.voiceStart, n.voiceEnd, n.note, n.id)
+			case n := <-s.noteOff:
+				s.release(n)
+			case rowLength = <-s.setRowLength:
+			case patch := <-s.setPatch:
+				err := s.synth.Update(patch)
+				if err != nil {
+					s.Disable()
+					break
+				}
+			default:
+				renderTime := rowTimeRemaining
+				if rowTimeRemaining <= 0 {
+					rowOut := iterator(rowIn[:0])
+					if len(rowOut) > 0 {
+						curVoice := 0
+						for i, rn := range rowOut {
+							end := curVoice + rn.NumVoices
+							if rn.Note != 1 {
+								s.release(trackNotes[i])
+							}
+							if rn.Note > 1 {
+								id := s.getNewID()
+								s.trigger(curVoice, end, rn.Note, id)
+								trackNotes[i] = id
+							}
+							curVoice = end
+						}
+						rowTimeRemaining = rowLength
+						renderTime = rowLength
+						released = false
+					} else {
+						if !released {
+							s.releaseVoiceRange(0, len(s.voiceNoteID))
+							released = true
+						}
+						rowTimeRemaining = 0
+						renderTime = math.MaxInt32
+					}
+				}
+				rendered, timeAdvanced, err := s.synth.Render(buffer, renderTime)
+				if err != nil {
+					s.Disable()
+					break
+				}
+				rowTimeRemaining -= timeAdvanced
+				if timeAdvanced == 0 {
+					renderTries++
+				} else {
+					renderTries = 0
+				}
+				if renderTries >= SEQUENCER_MAX_READ_TRIES {
+					s.Disable()
+					break
+				}
+				err = audioOut.WriteAudio(buffer[:2*rendered])
+				if err != nil {
+					s.Disable()
+					break
+				}
 			}
 		}
-		if totalRendered*2 >= len(buffer) {
-			return totalRendered * 2, nil
-		}
 	}
-	return totalRendered * 2, fmt.Errorf("despite %v attempts, Sequencer.ReadAudio could not fill the buffer (rowLength was %v, should be >> 0)", SEQUENCER_MAX_READ_TRIES, s.rowLength)
-}
-
-// Updates the patch of the synth
-func (s *Sequencer) SetPatch(patch sointu.Patch) {
-	s.mutex.Lock()
-	var err error
-	if s.Enabled() {
-		err = s.synth.Update(patch)
-	} else {
-		s.synth, err = s.service.Compile(patch)
-	}
-	if err == nil {
-		atomic.StoreInt32(&s.validSynth, 1)
-	}
-	s.mutex.Unlock()
 }
 
 func (s *Sequencer) Enabled() bool {
@@ -121,32 +170,97 @@ func (s *Sequencer) Disable() {
 }
 
 func (s *Sequencer) SetRowLength(rowLength int) {
-	s.mutex.Lock()
-	s.rowLength = rowLength
-	s.mutex.Unlock()
+	s.setRowLength <- rowLength
+}
+
+// Close closes the sequencer and releases all its resources
+func (s *Sequencer) Close() {
+	s.closer <- struct{}{}
+}
+
+// SetPatch updates the synth to match given patch
+func (s *Sequencer) SetPatch(patch sointu.Patch) {
+	s.setPatch <- patch.Copy()
 }
 
 // Trigger is used to manually play a note on the sequencer when jamming. It is
-// thread-safe.
-func (s *Sequencer) Trigger(voice int, note byte) {
-	s.mutex.Lock()
-	s.doNote(voice, note)
-	s.mutex.Unlock()
+// thread-safe. It starts to play one of the voice in the range voiceStart
+// (inclusive) and voiceEnd (exclusive). It returns a release function that can
+// be called to release the voice playing the note (in case the voice has not
+// been captured by someone else already). Note that Trigger will never block,
+// but calling the release function might block until the sequencer has been
+// able to assign a voice to the note.
+func (s *Sequencer) Trigger(voiceStart, voiceEnd int, note byte) func() {
+	if note <= 1 {
+		return func() {}
+	}
+	id := s.getNewID()
+	e := noteOnEvent{
+		voiceStart: voiceStart,
+		voiceEnd:   voiceEnd,
+		note:       note,
+		id:         id,
+	}
+	s.noteOn <- e
+	return func() {
+		s.noteOff <- id // now, tell the sequencer to stop it
+	}
 }
 
-// Release is used to manually release a note on the sequencer when jamming. It
-// is thread-safe.
-func (s *Sequencer) Release(voice int) {
-	s.Trigger(voice, 0)
+func (s *Sequencer) getNewID() uint32 {
+	return atomic.AddUint32(&s.idCounter, 1)
 }
 
-// doNote is the internal trigger/release function that is not thread safe
-func (s *Sequencer) doNote(voice int, note byte) {
-	if s.synth != nil {
-		if note == 0 {
-			s.synth.Release(voice)
-		} else {
-			s.synth.Trigger(voice, note)
+func (s *Sequencer) enable() {
+	atomic.StoreInt32(&s.validSynth, 1)
+}
+
+func (s *Sequencer) trigger(voiceStart, voiceEnd int, note byte, newID uint32) {
+	if !s.Enabled() {
+		return
+	}
+	var oldestID uint32 = math.MaxUint32
+	oldestReleased := false
+	oldestVoice := 0
+	for i := voiceStart; i < voiceEnd; i++ {
+		// find a suitable voice to trigger. if the voice has been released,
+		// then we prefer to trigger that over a voice that is still playing. in
+		// case two voices are both playing or or both are released, we prefer
+		// the older one
+		id := s.voiceNoteID[i]
+		isReleased := s.voiceReleased[i]
+		if id < oldestID && (oldestReleased == isReleased) || (!oldestReleased && isReleased) {
+			oldestVoice = i
+			oldestID = id
+			oldestReleased = isReleased
+		}
+	}
+	s.voiceNoteID[oldestVoice] = newID
+	s.voiceReleased[oldestVoice] = false
+	s.synth.Trigger(oldestVoice, note)
+}
+
+func (s *Sequencer) release(id uint32) {
+	if !s.Enabled() {
+		return
+	}
+	for i := 0; i < len(s.voiceNoteID); i++ {
+		if s.voiceNoteID[i] == id && !s.voiceReleased[i] {
+			s.voiceReleased[i] = true
+			s.synth.Release(i)
+			return
+		}
+	}
+}
+
+func (s *Sequencer) releaseVoiceRange(voiceStart, voiceEnd int) {
+	if !s.Enabled() {
+		return
+	}
+	for i := voiceStart; i < voiceEnd; i++ {
+		if !s.voiceReleased[i] {
+			s.voiceReleased[i] = true
+			s.synth.Release(i)
 		}
 	}
 }

tracker/tracker.go

@@ -77,9 +77,10 @@ type Tracker struct {
 	BottomHorizontalSplit *Split
 	VerticalSplit         *Split
 	StackUse              []int
+	KeyPlaying            map[string]func()
 
 	sequencer    *Sequencer
-	ticked       chan struct{}
+	refresh      chan struct{}
 	setPlaying   chan bool
 	rowJump      chan int
 	patternJump  chan int
@@ -131,25 +132,6 @@ func (t *Tracker) TogglePlay() {
 	}
 }
 
-func (t *Tracker) sequencerLoop(closer <-chan struct{}) {
-	output := t.audioContext.Output()
-	defer output.Close()
-	buffer := make([]float32, 8192)
-	for {
-		select {
-		case <-closer:
-			return
-		default:
-			read, _ := t.sequencer.ReadAudio(buffer)
-			for read < len(buffer) {
-				buffer[read] = 0
-				read++
-			}
-			output.WriteAudio(buffer)
-		}
-	}
-}
-
 func (t *Tracker) ChangeOctave(delta int) bool {
 	newOctave := t.Octave.Value + delta
 	if newOctave < 0 {
@@ -557,7 +539,7 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 		setPlaying:            make(chan bool),
 		rowJump:               make(chan int),
 		patternJump:           make(chan int),
-		ticked:                make(chan struct{}),
+		refresh:               make(chan struct{}, 1), // use non-blocking sends; no need to queue extra ticks if one is queued already
 		closer:                make(chan struct{}),
 		undoStack:             []sointu.Song{},
 		redoStack:             []sointu.Song{},
@@ -567,6 +549,7 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 		BottomHorizontalSplit: new(Split),
 		VerticalSplit:         new(Split),
 		ChooseUnitTypeList:    &layout.List{Axis: layout.Vertical},
+		KeyPlaying:            make(map[string]func()),
 	}
 	t.UnitDragList.HoverItem = -1
 	t.InstrumentDragList.HoverItem = -1
@@ -578,12 +561,11 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 	for range allUnits {
 		t.ChooseUnitTypeBtns = append(t.ChooseUnitTypeBtns, new(widget.Clickable))
 	}
-	curVoices := make([]int, 32)
-	t.sequencer = NewSequencer(synthService, func() ([]Note, bool) {
+	t.sequencer = NewSequencer(2048, synthService, audioContext, func(row []RowNote) []RowNote {
 		t.playRowPatMutex.Lock()
 		if !t.Playing {
 			t.playRowPatMutex.Unlock()
-			return nil, false
+			return nil
 		}
 		t.PlayPosition.Row++
 		t.PlayPosition.Wrap(t.song)
@@ -591,28 +573,20 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 			t.Cursor.SongRow = t.PlayPosition
 			t.SelectionCorner.SongRow = t.PlayPosition
 		}
-		notes := make([]Note, 0, 32)
-		for track := range t.song.Tracks {
-			patternIndex := t.song.Tracks[track].Sequence[t.PlayPosition.Pattern]
-			note := t.song.Tracks[track].Patterns[patternIndex][t.PlayPosition.Row]
-			if note == 1 { // anything but hold causes an action.
-				continue
-			}
-			first := t.song.FirstTrackVoice(track)
-			notes = append(notes, Note{first + curVoices[track], 0})
-			if note > 1 {
-				curVoices[track]++
-				if curVoices[track] >= t.song.Tracks[track].NumVoices {
-					curVoices[track] = 0
-				}
-				notes = append(notes, Note{first + curVoices[track], note})
-			}
+		for _, track := range t.song.Tracks {
+			patternIndex := track.Sequence[t.PlayPosition.Pattern]
+			note := track.Patterns[patternIndex][t.PlayPosition.Row]
+			row = append(row, RowNote{Note: note, NumVoices: track.NumVoices})
 		}
 		t.playRowPatMutex.Unlock()
-		t.ticked <- struct{}{}
-		return notes, true
+		select {
+		case t.refresh <- struct{}{}:
+		default:
+			// message dropped, there's already a tick queued, so no need to queue extra
+		}
+
+		return row
 	})
-	go t.sequencerLoop(t.closer)
 	if err := t.LoadSong(defaultSong.Copy()); err != nil {
 		panic(fmt.Errorf("cannot load default song: %w", err))
 	}