splatter-tennis/audio.js

// All sound: WebAudio context, synthesized SFX, recorded umpire lines, speech fallback.

let AC = null;
export const audio = () => {
  if (!AC) AC = new (window.AudioContext || window.webkitAudioContext)();
  if (AC.state === 'suspended') AC.resume();
  return AC;
};

// Umpire lines are pre-recorded files (assets/audio/*.m4a) played via WebAudio —
// works on mobile where speechSynthesis is unreliable. say() remains the fallback.
const VOICE = {};
let reverbNode = null;
function reverb(ac) { // stadium PA tail: exponentially decaying noise as impulse response
  if (reverbNode) return reverbNode;
  const len = ac.sampleRate * 1.3, ir = ac.createBuffer(2, len, ac.sampleRate);
  for (let c = 0; c < 2; c++) {
    const d = ir.getChannelData(c);
    for (let i = 0; i < len; i++) d[i] = (Math.random() * 2 - 1) * Math.pow(1 - i / len, 2.8);
  }
  reverbNode = ac.createConvolver(); reverbNode.buffer = ir;
  const wet = ac.createGain(); wet.gain.value = 0.35;
  reverbNode.connect(wet).connect(ac.destination);
  return reverbNode;
}

// The umpire is one man with one microphone. Several triggers landing together used to play two or
// three lines on top of each other; a line that would start while he is still talking is DROPPED.
// The check happens at play time (not call time) so a first-play fetch/decode is judged fairly.
let voiceUntil = 0;

export function voice(name, delay = 0, rate = 1) {
  const ac = audio();
  const play = buf => {
    const at = ac.currentTime + delay;
    if (at < voiceUntil) return;
    voiceUntil = at + buf.duration / rate + 0.2; // + a breath, so lines never butt against each other
    const src = ac.createBufferSource(); src.buffer = buf;
    src.playbackRate.value = rate; // < 1 = slower and lower — the umpire's dark register
    src.connect(ac.destination); // dry
    const send = ac.createGain(); send.gain.value = 1.8; // umpire rides a wetter PA tail than the crowd sfx
    src.connect(send).connect(reverb(ac)); // extra reverb send — the big-stadium announcer echo
    src.start(ac.currentTime + delay);
  };
  if (VOICE[name]) return play(VOICE[name]);
  fetch('assets/audio/' + name + '.m4a')
    .then(r => { if (!r.ok) throw 0; return r.arrayBuffer(); })
    .then(ab => ac.decodeAudioData(ab))
    .then(buf => { VOICE[name] = buf; play(buf); })
    .catch(() => say(name.replace(/_/g, ' '), delay));
}

// Recorded one-shot SFX (assets/audio/tennis-*.wav): ball hits, applause, the crowd's aww.
// Same load-once-then-cache pattern as voice(), but dry (no PA reverb) and with a volume knob.
const SFX = {};
export function sfx(name, vol = 1, opts = {}) {
  const ac = audio();
  const play = buf => {
    const src = ac.createBufferSource(); src.buffer = buf;
    if (opts.rate) src.playbackRate.value = opts.rate; // < 1 stretches it a touch longer (and lower)
    const g = ac.createGain(); g.gain.value = vol;
    src.connect(g).connect(ac.destination);
    if (opts.reverb) g.connect(reverb(ac)); // wet stadium tail on top of the dry sample
    src.start();
  };
  if (SFX[name]) return play(SFX[name]);
  fetch('assets/audio/' + name + '.wav')
    .then(r => { if (!r.ok) throw 0; return r.arrayBuffer(); })
    .then(ab => ac.decodeAudioData(ab))
    .then(buf => { SFX[name] = buf; play(buf); })
    .catch(() => {}); // missing sample = silence, never a thrown error mid-rally
}

// the crowd's groan — stretched a touch and pushed through the PA reverb for a longer, wetter sigh
export function aww(vol = 1) { sfx('tennis-aww', vol * 0.5, { reverb: true }); }

// Looping background beds (scene atmosphere, mode music): each starts once, highpass 'lowcut' + quiet gain.
const beds = new Map(); // file -> {ac, g, vol} once playing (null while loading); see fadeBed
const ducked = new Set(); // beds asked to duck while they were STILL LOADING — see fadeBed
function loopBed(file, lowcut, vol, loopEnd = 0) {
  // audio() FIRST, before the already-started early return: it is also what RESUMES a context the
  // browser suspended under its autoplay policy. The menu theme is started at boot, before any
  // gesture exists, so it plays into a suspended context and stays silent — and the call that has
  // to wake it up is a second menuMusic() from the first tap, which would otherwise return here
  // without ever reaching audio().
  const ac = audio();
  if (beds.has(file)) return;
  beds.set(file, null);
  fetch('assets/audio/' + file) // full filename: the beds are a mix of .wav and .m4a, see below
    .then(r => { if (!r.ok) throw 0; return r.arrayBuffer(); })
    .then(ab => ac.decodeAudioData(ab))
    .then(buf => {
      const src = ac.createBufferSource(); src.buffer = buf; src.loop = true;
      // loopEnd = the source's TRUE length, for a bed that is compressed. AAC pads the last packet,
      // and Chrome hands back a buffer ~17 ms longer than the master — silence spliced in at every
      // seam, once a loop, on the title screen. Trimming the seam is what keeps the loop seamless.
      // Zero (the default, and every uncompressed bed) leaves the whole buffer in play.
      if (loopEnd) src.loopEnd = loopEnd;
      const hp = ac.createBiquadFilter(); hp.type = 'highpass'; hp.frequency.value = lowcut;
      // start SILENT if it was ducked while loading: a multi-megabyte file takes seconds to fetch
      // and decode, and a player who taps straight through the picker would otherwise have the
      // menu theme come up over the match, several seconds late, at full level.
      const g = ac.createGain(); g.gain.value = ducked.has(file) ? 0 : vol;
      src.connect(hp).connect(g).connect(ac.destination); src.start();
      beds.set(file, { ac, g, vol });
    })
    .catch(() => beds.delete(file)); // failed start (decode/network) can retry next call
}
export const ambient = () => loopBed('tennis-ambient-loop.wav', 500, 0.035);  // whole-scene atmosphere, from first tap
// ...and the splatter bed, same treatment: 5.9 MB of 24-bit WAV down to 287 KB. Its master is
// 982597 frames at 48 kHz, which is the un-round 20.47077 s below — an AAC loop needs the SOURCE
// length as loopEnd, not the decoder's padded one. See the note on menuMusic.
export const zombieMusic = () => loopBed('zombie-mode.m4a', 800, 0.2, 20.47077);
// Menu theme: every menu screen and the death summary. Barely highpassed — this one is MUSIC, not
// an atmosphere bed, so the low end is the point. Started by the FIRST TAP (main.js `go`), never at
// boot: a title screen that starts playing at you before you have touched it is rude, and on a phone
// the autoplay policy would have held it silent until that tap anyway.
// AAC, not WAV: 48 s of stereo music is 8.3 MB as a WAV and this one downloads on every page load,
// before the player has decided to play anything. 768 KB encoded, and the master is exactly 48.000 s
// — which is the loopEnd, because the decoded buffer is NOT (measured 48.0174 s in Chrome; see the
// padding note in loopBed). Re-encode the file and you must re-measure that number:
//   fetch(f).then(r=>r.arrayBuffer()).then(a=>new AudioContext().decodeAudioData(a)).then(b=>b.duration)
export const menuMusic = () => loopBed('background-music.m4a', 30, 0.5, 48);

// duck a bed to silence (out=true) or back to its base level over `secs` — the sudden-death duel mutes the music
function fadeBed(file, out, secs = 0.7) {
  if (out) ducked.add(file); else ducked.delete(file);
  const b = beds.get(file);
  if (!b) return; // still loading — the flag above is the level it will start at
  const t = b.ac.currentTime;
  b.g.gain.cancelScheduledValues(t);
  b.g.gain.setValueAtTime(b.g.gain.value, t); // anchor at current level so a mid-fade toggle stays smooth
  b.g.gain.linearRampToValueAtTime(out ? 0 : b.vol, t + secs);
}
export const zombieDuck = out => fadeBed('zombie-mode.m4a', out); // key must match loopBed's, filename and all
// The menu theme is never stopped, only faded — the buffer is already decoded, so fading it back up
// on the death screen costs nothing and can't miss its cue waiting on a re-fetch.
export const menuDuck = out => fadeBed('background-music.m4a', out);

let sysVoice = null;
export function say(text, delay = 0) { // fallback when a recorded umpire line is missing
  try {
    if (!sysVoice) sysVoice = speechSynthesis.getVoices().find(v => v.lang.startsWith('en-GB')) || null;
    const u = new SpeechSynthesisUtterance(text);
    if (sysVoice) u.voice = sysVoice; u.rate = 0.88; u.pitch = 0.75; u.volume = 0.9;
    setTimeout(() => speechSynthesis.speak(u), delay * 1000);
  } catch (e) {}
}

function noiseBuf(ac, len) {
  const b = ac.createBuffer(1, ac.sampleRate * len, ac.sampleRate), d = b.getChannelData(0);
  for (let i = 0; i < d.length; i++) d[i] = Math.random() * 2 - 1;
  return b;
}

// Filtered noise sweep. Default = the racket cutting air (rising, short) — the sound of a whiff.
// The sweep is parameterised because a DESCENDING, longer one is a panel swooshing in and settling:
// same six lines of Web Audio, opposite reading. See whoosh() below.
export function swish(vol = 0.3, f0 = 1600, f1 = 3200, dur = 0.16) {
  try {
    const ac = audio(), t = ac.currentTime;
    const src = ac.createBufferSource(); src.buffer = noiseBuf(ac, dur);
    const bp = ac.createBiquadFilter(); bp.type = 'bandpass'; bp.frequency.setValueAtTime(f0, t);
    bp.frequency.exponentialRampToValueAtTime(f1, t + dur * 0.75); bp.Q.value = 1.5;
    const g = ac.createGain();
    g.gain.setValueAtTime(0.001, t); g.gain.exponentialRampToValueAtTime(vol, t + dur * 0.3);
    g.gain.exponentialRampToValueAtTime(0.001, t + dur);
    src.connect(bp).connect(g).connect(ac.destination); src.start();
  } catch (e) {}
}
export const whoosh = (vol = 0.34) => swish(vol, 4200, 700, 0.3); // a panel flying in and settling

export function pock(vol = 0.8, freq = 900) { // racket contact / bounce thock
  try {
    const ac = audio(), t = ac.currentTime;
    const src = ac.createBufferSource(); src.buffer = noiseBuf(ac, 0.06);
    const bp = ac.createBiquadFilter(); bp.type = 'bandpass'; bp.frequency.value = freq; bp.Q.value = 1.2;
    const g = ac.createGain();
    g.gain.setValueAtTime(vol, t); g.gain.exponentialRampToValueAtTime(0.001, t + 0.07);
    src.connect(bp).connect(g).connect(ac.destination); src.start();
    const o = ac.createOscillator(), og = ac.createGain(); // low thump body
    o.frequency.setValueAtTime(180, t); o.frequency.exponentialRampToValueAtTime(70, t + 0.08);
    og.gain.setValueAtTime(vol * 0.5, t); og.gain.exponentialRampToValueAtTime(0.001, t + 0.09);
    o.connect(og).connect(ac.destination); o.start(t); o.stop(t + 0.1);
  } catch (e) {}
}

export function splat(vol = 0.7) { // wet burst — a zombie meets a first serve
  try {
    const ac = audio(), t = ac.currentTime;
    const src = ac.createBufferSource(); src.buffer = noiseBuf(ac, 0.22);
    const lp = ac.createBiquadFilter(); lp.type = 'lowpass';
    lp.frequency.setValueAtTime(1400, t); lp.frequency.exponentialRampToValueAtTime(180, t + 0.2);
    const g = ac.createGain();
    g.gain.setValueAtTime(vol, t); g.gain.exponentialRampToValueAtTime(0.001, t + 0.22);
    src.connect(lp).connect(g).connect(ac.destination); src.start();
    const o = ac.createOscillator(), og = ac.createGain(); // body thud
    o.frequency.setValueAtTime(120, t); o.frequency.exponentialRampToValueAtTime(45, t + 0.15);
    og.gain.setValueAtTime(vol * 0.7, t); og.gain.exponentialRampToValueAtTime(0.001, t + 0.16);
    o.connect(og).connect(ac.destination); o.start(t); o.stop(t + 0.18);
  } catch (e) {}
}

export function boom(vol = 0.9) { // bomb ball — sub-bass thump under a filtered noise blast
  try {
    const ac = audio(), t = ac.currentTime;
    const o = ac.createOscillator(), og = ac.createGain(); // 80Hz sine diving to 30Hz
    o.frequency.setValueAtTime(80, t); o.frequency.exponentialRampToValueAtTime(30, t + 0.35);
    og.gain.setValueAtTime(vol, t); og.gain.exponentialRampToValueAtTime(0.001, t + 0.4);
    o.connect(og).connect(ac.destination); o.start(t); o.stop(t + 0.42);
    const src = ac.createBufferSource(); src.buffer = noiseBuf(ac, 0.4); // the blast
    const lp = ac.createBiquadFilter(); lp.type = 'lowpass';
    lp.frequency.setValueAtTime(2200, t); lp.frequency.exponentialRampToValueAtTime(200, t + 0.35);
    const g = ac.createGain();
    g.gain.setValueAtTime(vol * 0.8, t); g.gain.exponentialRampToValueAtTime(0.001, t + 0.4);
    src.connect(lp).connect(g).connect(ac.destination); src.start(t);
  } catch (e) {}
}

export function shriek(vol = 0.35) { // a runner announces itself — harsh rising cry, the fairness contract
  try {
    const ac = audio(), t = ac.currentTime, dur = 0.7;
    const o = ac.createOscillator(); o.type = 'sawtooth';
    o.frequency.setValueAtTime(300, t);
    o.frequency.exponentialRampToValueAtTime(950, t + 0.25);
    o.frequency.exponentialRampToValueAtTime(500, t + dur);
    const bp = ac.createBiquadFilter(); bp.type = 'bandpass'; bp.frequency.value = 1400; bp.Q.value = 0.8;
    const g = ac.createGain();
    g.gain.setValueAtTime(0.001, t); g.gain.exponentialRampToValueAtTime(vol, t + 0.06);
    g.gain.exponentialRampToValueAtTime(0.001, t + dur);
    o.connect(bp).connect(g).connect(ac.destination); o.start(t); o.stop(t + dur + 0.05);
  } catch (e) {}
}

export function moan(vol = 0.1) { // distant undead ambience
  try {
    const ac = audio(), t = ac.currentTime, dur = 1.2 + Math.random() * 0.8;
    const o = ac.createOscillator(); o.type = 'sawtooth';
    const f0 = 65 + Math.random() * 45;
    o.frequency.setValueAtTime(f0, t);
    o.frequency.linearRampToValueAtTime(f0 * 1.25, t + dur * 0.4);
    o.frequency.linearRampToValueAtTime(f0 * 0.9, t + dur);
    const lp = ac.createBiquadFilter(); lp.type = 'lowpass'; lp.frequency.value = 320;
    const g = ac.createGain();
    g.gain.setValueAtTime(0.001, t); g.gain.exponentialRampToValueAtTime(vol, t + dur * 0.3);
    g.gain.exponentialRampToValueAtTime(0.001, t + dur);
    o.connect(lp).connect(g).connect(ac.destination); o.start(t); o.stop(t + dur + 0.05);
  } catch (e) {}
}

export function applause(seconds = 2.4, vol = 0.5) { // ponytail: synthesized claps; swap for a sample if it reads flat
  try {
    const ac = audio(), t0 = ac.currentTime, n = 90 * seconds;
    for (let i = 0; i < n; i++) {
      const t = t0 + Math.random() * seconds;
      const env = Math.min(1, 4 * (1 - Math.abs(2 * (t - t0) / seconds - 1))); // fade in/out
      const src = ac.createBufferSource(); src.buffer = noiseBuf(ac, 0.025);
      const bp = ac.createBiquadFilter(); bp.type = 'bandpass';
      bp.frequency.value = 1000 + Math.random() * 1600; bp.Q.value = 2.5;
      const g = ac.createGain();
      g.gain.setValueAtTime(vol * env * (0.3 + Math.random() * 0.7), t);
      g.gain.exponentialRampToValueAtTime(0.001, t + 0.03);
      src.connect(bp).connect(g).connect(ac.destination); src.start(t);
    }
  } catch (e) {}
}