Patterns and songs (#333, #334) have to play sample-accurate in time,
whatever the frame rate does. What is counted in game time runs away
from the sound. This lays the ground: musical time, a scheduler that
plans notes ahead on the audio clock, and a player that starts and ends
a note at a given second. Nothing in the editor plays a sequence yet,
the check scripts drive it through `__gm.music`.
- Ticks, 480 to the quarter as in MIDI files (decided in #332).
Triplets and quintuplets land on whole ticks. Any meter, a beat being
the note value under the line. The tempo always counts quarters.
- `core/music/sequence.ts` is a pure rule: the notes starting in a
window of playing time. Across the end of a loop it looks into the
next round, so the seam has no gap. A note past the loop end ends
there. Windows are whole ticks, and the seam is stepped exactly, so
no rounding can drop the first note of a round.
- `core/music/Scheduler.ts` plans the next 100 ms every 25 ms through a
host, so it is tested with a clock of its own. The first note sounds
50 ms after the start. Changes to the sequence are heard from the
next window on. Stop and seek fade what it started. A new tempo or
loop counts from what is planned, and the playhead keeps its old
pace until the clock gets there.
- The position is the audio clock less `outputLatency`, as bar, beat
and tick.
- The beat comes from a Web Worker (`viewport/musicTimer.ts`), which
keeps its pace in a hidden tab.
- The sound library starts a note at `timing.at`: a buffer source by
`start(when)`, the pitch worklet by counting down inside the render
block it falls in. A note's end is set on the clock at once, its
fade to the sample. Leaving a loop still waits for the page.
- Delay synced to beats (decided in #332, noted from #327): a setting
`Sync` (Seconds / Beats), `time` then in quarter notes, held to the
2 s of the line. Play sound and Play note have an input `tempo`,
120 BPM where nothing is connected. A scheduled note carries the
tempo of its sequence.
- Swing is left for #333/#334, as decided.
Also fixes the red suite of 6f1f315 (task 526). Three checks in e2e 34
waited on the page's clock for things that run on the audio clock. In
CI the voice was already 0.7 s old when first seen, and the 0.3 s note
of Play note was over. `stats().last` now says when a voice started on
the audio clock, and the Quad, Step and Play note checks hold every
reading against it.
Tests:
- music.test.ts (new): 17 tests, time, windows, loop seam, scheduler
with a jittery timer, stop, seek, tempo change
- sound-library +4, soundfx +1, node-catalog +2 (tempo inputs)
- Counter-checks: an unclamped note length, a window that never moves
on, a buffer source ignoring its start time and a Delay ignoring
Beats each turn 1, 6, 1 and 2 tests red
- e2e 34 on melektaus-atx: ALL PASSED, 47 checks (+2). Nine notes of a
looped bar at 150 BPM exactly 0.4 s apart, each planned 89 to 91 ms
ahead. The position matched the clock less 32 ms latency to the
tick. Offline the worklet started on samples 590, 12000 and 15200.
- Gate on melektaus-atx: CHECK EXIT 0, 244 test files, 3786 tests
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
