Soft Real-Time Sequencer in TypeScript

Library that allows users to schedule a list of changes to a Vuex(v.3) store's state. Can optionally sync with a server that is running timesync. An esm module written in TypeScript, tested in the browser but it should also run on the server.

Getting Started

npm install stark-sequencer

Usage and Options

import { StarkSequencer } from "stark-sequencer";

// Default options. Will sync from the page's URL/timesync by default.
let options = {
    isSync: false,
    host: "",
    path: "timesync"
  };
StarkSequencer.init({options});

// Monitor a time-based process like a movie or audio track.
let mockTrackTime = 0;
let monitor = StarkSequencer.monitor({
    length: 30e3,  // Used for automatic destruction at the end. Default: 10 min.
    pollCallback: () => mockTrackTime,  // Get the time from the track.
    start: Date.now() + 5e3, // Start at the synched time. Default: starts immediately.
    pollInterval: 2e2,  // In milliseconds, min 15ms. Default: 100ms.
    diffInterval: 30,  // Margin of error in milliseconds. Default: 100ms.

    // Update the store's time even if 
    // the polled time matches the monitored time.
    // Default: false.
    isForceUpdate: true,
    isRepeat: false   // Control for looping. Default: false.
  });

// Execute mutations on the Vuex store.
let executor = StarkSequencer.execute({
    init: { x: 0, y: 0 },  // The initial object state. Default: {}.

    // Events sequence.
    events: [
      {time: 200, value: { x: 20, y: 0 }},
      {time: 400, value: { x: 20, y: 40 }},
      {time: 600, value: { x: 40, y: 40 }},
      ...etc
    ],
    buffer: 50, // Number of buffered events. Default: 100.
    start: Date.now() + 5e3, // Start at the synched time. Default: starts immediately.

    // In milliseconds. Optional, min 15ms. 
    // Default = 15ms < min time between events / 2 < 150ms.
    pollInterval: 2e2,
    isRepeat: true  // Control for looping. Default: false.
  });

Results

Watch for changes, the user can use a framework like Vue to update the DOM.

let currentTime = Date.now();

// Output
// time: Current prescribed and synched time.
// startTime: Synchronized time for the beginning of the sequence.
// updateTime: Time of last update.
// isEnd:  Flag can be set for premature kill signal, or set when the sequence is finished.
monitor.state.subscribe((mutation, state) => {
  mockTrackTime = state.time;  // This would scrub the media in a real use case.

  // If you enabled sync, an updated offset value in ms can be accessed here.
  let offset = StarkSequencer.offsetPointer.offset;

  console.log(`Time: ${state.updateTime - currentTime - offset}, Value: ${mockTrackTime}`);
});

// Output
// value: Current state.
// startTime: Synchronized time for the beginning of the sequence.
// updateTime: Time of last update.
// isEnd: Flag can be set for premature kill signal, or set when the sequence is finished.
executor.state.subscribe((mutation, state) => {
  
  // If you enabled sync, an updated offset value in ms can be accessed here.
  let offset = StarkSequencer.offsetPointer.offset;

  console.log(`Time: ${state.updateTime - currentTime - offset}, Value: ${state.value}`);
});

Destroy

monitor.delete();
executor.delete();