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feat(tracker): rework the MIDI input and note event handling

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This commit is contained in:
5684185+vsariola@users.noreply.github.com
2025-06-03 20:03:22 +03:00
parent 7ef868a434
commit 283fbc1171
19 changed files with 428 additions and 500 deletions
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86
tracker/gomidi/midi.go
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@ -19,24 +19,15 @@ import (
type (
RTMIDIContext struct {
driver *rtmididrv.Driver
currentIn drivers.In
events chan timestampedMsg
eventsBuf []timestampedMsg
eventIndex int
startFrame int
startFrameSet bool
driver *rtmididrv.Driver
currentIn drivers.In
broker *tracker.Broker
}
RTMIDIDevice struct {
context *RTMIDIContext
in drivers.In
}
timestampedMsg struct {
frame int
msg midi.Message
}
)
func (m *RTMIDIContext) InputDevices(yield func(tracker.MIDIDevice) bool) {
@ -56,8 +47,8 @@ func (m *RTMIDIContext) InputDevices(yield func(tracker.MIDIDevice) bool) {
}
// Open the driver.
func NewContext() *RTMIDIContext {
m := RTMIDIContext{events: make(chan timestampedMsg, 1024)}
func NewContext(broker *tracker.Broker) *RTMIDIContext {
m := RTMIDIContext{broker: broker}
// there's not much we can do if this fails, so just use m.driver = nil to
// indicate no driver available
m.driver, _ = rtmididrv.New()
@ -94,69 +85,16 @@ func (d RTMIDIDevice) String() string {
}
func (m *RTMIDIContext) HandleMessage(msg midi.Message, timestampms int32) {
select {
case m.events <- timestampedMsg{frame: int(int64(timestampms) * 44100 / 1000), msg: msg}: // if the channel is full, just drop the message
default:
var channel, key, velocity uint8
if msg.GetNoteOn(&channel, &key, &velocity) {
ev := tracker.NoteEvent{Timestamp: int64(timestampms) * 441 / 10, On: true, Channel: int(channel), Note: key, Source: m}
tracker.TrySend(m.broker.MIDIChannel(), any(ev))
} else if msg.GetNoteOff(&channel, &key, &velocity) {
ev := tracker.NoteEvent{Timestamp: int64(timestampms) * 441 / 10, On: false, Channel: int(channel), Note: key, Source: m}
tracker.TrySend(m.broker.MIDIChannel(), any(ev))
}
}
func (c *RTMIDIContext) NextEvent(frame int) (event tracker.MIDINoteEvent, ok bool) {
F:
for {
select {
case msg := <-c.events:
c.eventsBuf = append(c.eventsBuf, msg)
if !c.startFrameSet {
c.startFrame = msg.frame
c.startFrameSet = true
}
default:
break F
}
}
if c.eventIndex > 0 { // an event was consumed, check how badly we need to adjust the timing
delta := frame + c.startFrame - c.eventsBuf[c.eventIndex-1].frame
// delta should never be a negative number, because the renderer does
// not consume an event until current frame is past the frame of the
// event. However, if it's been a while since we consumed event, delta
// may by *positive* i.e. we consume the event too late. So adjust the
// internal clock in that case.
c.startFrame -= delta / 5 // adjust the start frame towards the consumed event
}
for c.eventIndex < len(c.eventsBuf) {
var channel uint8
var velocity uint8
var key uint8
m := c.eventsBuf[c.eventIndex]
f := m.frame - c.startFrame
c.eventIndex++
if m.msg.GetNoteOn(&channel, &key, &velocity) {
return tracker.MIDINoteEvent{Frame: f, On: true, Channel: int(channel), Note: key}, true
} else if m.msg.GetNoteOff(&channel, &key, &velocity) {
return tracker.MIDINoteEvent{Frame: f, On: false, Channel: int(channel), Note: key}, true
}
}
c.eventIndex = len(c.eventsBuf) + 1
return tracker.MIDINoteEvent{}, false
}
func (c *RTMIDIContext) FinishBlock(frame int) {
c.startFrame += frame
if c.eventIndex > 0 {
copy(c.eventsBuf, c.eventsBuf[c.eventIndex-1:])
c.eventsBuf = c.eventsBuf[:len(c.eventsBuf)-c.eventIndex+1]
if len(c.eventsBuf) > 0 {
// Events were not consumed this round; adjust the start frame
// towards the future events. What this does is that it tries to
// render the events at the same time as they were received here
// delta will be always a negative number
delta := c.startFrame - c.eventsBuf[0].frame
c.startFrame -= delta / 5
}
}
c.eventIndex = 0
}
func (c *RTMIDIContext) BPM() (bpm float64, ok bool) {
return 0, false
}