sointu/tracker/recording.go
2024-03-10 20:01:13 +02:00

154 lines
4.8 KiB
Go

package tracker
import (
"bytes"
"errors"
"math"
"github.com/vsariola/sointu"
)
type Recording struct {
BPM float64 // vsts allow bpms as floats so for accurate reconstruction, keep it as float for recording
Events []MIDINoteEvent
TotalFrames int
}
type recordingNote struct {
note byte
startRow int
endRow int
}
var ErrInvalidRows = errors.New("rows per beat and rows per pattern must be greater than 1")
func (recording *Recording) Score(patch sointu.Patch, rowsPerBeat, rowsPerPattern int) (sointu.Score, error) {
if rowsPerBeat <= 1 || rowsPerPattern <= 1 {
return sointu.Score{}, ErrInvalidRows
}
channelNotes := make([][]recordingNote, 0)
// find the length of each note and assign it to its respective channel
for i, m := range recording.Events {
if !m.On || m.Channel >= len(patch) {
continue
}
endFrame := math.MaxInt
for j := i + 1; j < len(recording.Events); j++ {
if recording.Events[j].Channel == m.Channel && recording.Events[j].Note == m.Note {
endFrame = recording.Events[j].Frame
break
}
}
for len(channelNotes) <= m.Channel {
channelNotes = append(channelNotes, make([]recordingNote, 0))
}
startRow := frameToRow(recording.BPM, rowsPerBeat, m.Frame)
endRow := frameToRow(recording.BPM, rowsPerBeat, endFrame)
channelNotes[m.Channel] = append(channelNotes[m.Channel], recordingNote{m.Note, startRow, endRow})
}
//assign notes to tracks, assigning it to left most track that is released
// if none is released, assign it to new track if there's any. otherwise, assign it to the left most track
tracks := make([][][]recordingNote, len(channelNotes))
for i, c := range channelNotes {
tracks[i] = make([][]recordingNote, 0)
noteloop:
for _, n := range c {
// if a track is release, assign the note to left-most released track
for k, t := range tracks[i] {
if len(t) == 0 || t[len(t)-1].endRow <= n.startRow {
tracks[i][k] = append(t, n)
continue noteloop
}
}
// if there's space for more tracks, create one
if len(tracks[i]) < patch[i].NumVoices {
tracks[i] = append(tracks[i], []recordingNote{n})
continue noteloop
}
// otherwise, put the note to the track that was triggered longest time ago
oldestIndex := -1
oldestRow := math.MaxInt
for k, t := range tracks[i] {
if r := t[len(t)-1].startRow; r < oldestRow {
oldestRow = r
oldestIndex = k
}
}
tracks[i][oldestIndex] = append(tracks[i][oldestIndex], n)
}
}
// if there was tracks that had no notes, create empty tracks for them
for i := range channelNotes {
if l := len(tracks[i]); l == 0 && l < patch[i].NumVoices {
tracks[i] = append(tracks[i], []recordingNote{})
}
}
songLengthPatterns := (frameToRow(recording.BPM, rowsPerBeat, recording.TotalFrames) + rowsPerPattern - 1) / rowsPerPattern
songLengthRows := songLengthPatterns * rowsPerPattern
songTracks := make([]sointu.Track, 0)
for i, tg := range tracks {
for j, t := range tg {
// construct flat linear note arrays for tracks
flatPattern := make(sointu.Pattern, songLengthRows)
for k := range flatPattern {
flatPattern[k] = 1 // set all notes as holds at first
}
for _, n := range t {
if n.startRow >= songLengthRows {
continue
}
flatPattern[n.startRow] = n.note
if n.endRow < songLengthRows {
for l := n.startRow + 1; l < n.endRow; l++ {
flatPattern[l] = 1
}
flatPattern[n.endRow] = 0
} else {
for l := n.startRow + 1; l < songLengthRows; l++ {
flatPattern[l] = 1
}
}
}
// calculate number of voices, distributing the total number of voices to the different tracks
numVoices := (patch[i].NumVoices + len(tg) - j - 1) / len(tg)
// construct patterns
order := make(sointu.Order, songLengthPatterns)
patterns := make([]sointu.Pattern, 0)
L:
for k := range order {
p := flatPattern[k*rowsPerPattern : (k+1)*rowsPerPattern]
allHolds := true
for _, n := range p {
if n != 1 {
allHolds = false
break
}
}
if allHolds {
order[k] = -1
continue L
}
for l, p2 := range patterns {
if bytes.Equal(p, p2) {
order[k] = l
continue L
}
}
// make a copy of the slice so they are all independent and don't accidentally expand to same memory
newPat := make(sointu.Pattern, len(p))
copy(newPat, p)
order[k] = len(patterns)
patterns = append(patterns, newPat)
}
track := sointu.Track{NumVoices: numVoices, Effect: false, Order: order, Patterns: patterns}
songTracks = append(songTracks, track)
}
}
score := sointu.Score{Length: songLengthPatterns, RowsPerPattern: rowsPerPattern, Tracks: songTracks}
return score, nil
}
func frameToRow(BPM float64, rowsPerBeat, frame int) int {
return int(float64(frame)/44100/60*BPM*float64(rowsPerBeat) + 0.5)
}