sync midi by frames rather than useconds

src/main.rs

@@ -107,6 +107,13 @@ pub fn main () -> Usually<()> {
                 08 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
                 12 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
             }));
+            track.add_phrase("5 kicks", ppq * 4, Some(phrase! {
+                00 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
+                04 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
+                08 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
+                12 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
+                14 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
+            }));
             track.add_phrase("D-Beat", ppq * 4, Some(phrase! {
                 00 * ppq/4 => MidiMessage::NoteOn { key: 44.into(), vel: 100.into() },
                 00 * ppq/4 => MidiMessage::NoteOn { key: 36.into(), vel: 100.into() },
@@ -175,9 +182,9 @@ pub fn main () -> Usually<()> {
         state.scenes = vec![
             Scene::new("Intro",  vec![None,    Some(0), None,    None]),
             Scene::new("Hook",   vec![Some(0), Some(1), None,    None]),
-            Scene::new("Verse",  vec![Some(1), Some(0), Some(0), None]),
+            Scene::new("Verse",  vec![Some(2), Some(0), Some(0), None]),
-            Scene::new("Chorus", vec![Some(0), Some(1), None,    None]),
+            Scene::new("Chorus", vec![Some(1), Some(1), None,    None]),
-            Scene::new("Bridge", vec![Some(2), Some(0), Some(0), None]),
+            Scene::new("Bridge", vec![Some(3), Some(0), Some(0), None]),
             Scene::new("Outro",  vec![None,    Some(1), None,    None]),
         ];
 

src/model.rs

@@ -32,7 +32,7 @@ pub struct App {
     /// Current position according to transport
     pub playhead:     usize,
     /// Position of T0 for this playback within global timeline
-    pub play_started: Option<usize>,
+    pub play_started: Option<(usize, usize)>,
     /// Current sample rate and tempo.
     pub timebase:     Arc<Timebase>,
     /// Display mode of grid section
@@ -86,7 +86,10 @@ process!(App |self, _client, scope| {
     if self.playing != Some(transport.state) {
         match transport.state {
             TransportState::Rolling => {
-                self.play_started = Some(current_usecs as usize);
+                self.play_started = Some((
+                    current_frames as usize,
+                    current_usecs  as usize,
+                ));
             },
             TransportState::Stopped => {
                 self.play_started = None;

src/model/phrase.rs

@@ -44,12 +44,12 @@ impl Phrase {
         output:   &mut MIDIChunk,
         notes_on: &mut Vec<bool>,
         timebase: &Arc<Timebase>,
-        (usec0, usecs, _): (usize, usize, f64),
+        (frame0, frames, _): (usize, usize, f64),
     ) {
-        let start  = timebase.usecs_frames(usec0 as f64);
+        let start  = frame0;
-        let end    = timebase.usecs_frames((usec0 + usecs) as f64);
+        let end    = frame0 + frames;
         let repeat = timebase.pulses_frames(self.length as f64);
-        let ticks  = timebase.frames_to_ticks(start, end, repeat);
+        let ticks  = timebase.frames_to_ticks(start as f64, end as f64, repeat);
         //panic!("{start} {end} {repeat} {ticks:?}");
         for (time, tick) in ticks.iter() {
             if let Some(events) = self.notes.get(&(*tick as usize)) {
@@ -84,11 +84,13 @@ impl Timebase {
         //panic!("{start_frame} {end_frame} {fpt}");
         let mut ticks       = vec![];
         let mut add_frame   = |frame: f64|{
-            let jitter      = frame.rem_euclid(fpt);
+            let jitter      = frame.rem_euclid(fpt); // ramps
-            let last_jitter = (frame - 1.0).max(0.0) % fpt;
+            let next_jitter = (frame + 1.0).rem_euclid(fpt);
-            let next_jitter = frame + 1.0 % fpt;
+            if jitter > next_jitter { // at head of ramp crossing
-            if jitter <= last_jitter && jitter <= next_jitter {
+                ticks.push((
-                ticks.push((frame as usize % (end as usize-start as usize), (frame / fpt) as usize));
+                    frame as usize % (end as usize-start as usize),
+                    (frame / fpt) as usize)
+                );
             };
         };
         if start_frame < end_frame {

src/model/track.rs

@@ -119,7 +119,7 @@ impl Track {
         input:    MidiIter,
         timebase: &Arc<Timebase>,
         playing:  Option<TransportState>,
-        started:  Option<usize>,
+        started:  Option<(usize, usize)>,
         quant:    usize,
         reset:    bool,
         scope:    &ProcessScope,
@@ -145,13 +145,13 @@ impl Track {
         // Play from phrase into output buffer
         let phrase = &mut self.sequence.map(|id|self.phrases.get_mut(id)).flatten();
         if playing == Some(TransportState::Rolling) {
-            if let Some(started) = started {
+            if let Some((start_frame, start_usec)) = started {
                 if let Some(phrase) = phrase {
                     phrase.process_out(
                         &mut self.midi_out_buf,
                         &mut self.notes_on,
                         timebase,
-                        (usec0 - started, usecs, period)
+                        (frame0.saturating_sub(start_frame), frames, period)
                     );
                 }
             }