games: real recorded foley for cards and chips, synth for the rest

The card and chip sounds never convinced as oscillators, so they're now
CC0 recordings (Kenney's casino pack) under /static/audio/casino, embedded
in the binary. Six names (card, deal, flip, shuffle, chip, sweep) play
several rotating takes with a little pitch jitter; everything melodic stays
synthesised. PeteSFX's API is unchanged and synthesis is the fallback while
an ogg is still decoding, so no caller changed and the table is never silent.

internal/web/static/audio/casino/LICENSE.txt

@@ -0,0 +1,21 @@
+	
+
+	Casino Audio
+
+	by  Kenney Vleugels (Kenney.nl)
+
+			------------------------------
+
+	License (Creative Commons Zero, CC0)
+	http://creativecommons.org/publicdomain/zero/1.0/
+
+	You may use these assets in personal and commercial projects.
+	Credit (Kenney or www.kenney.nl) would be nice but is not mandatory.
+
+			------------------------------
+
+	Donate:   http://support.kenney.nl
+	Request:  http://request.kenney.nl
+
+	Follow on Twitter for updates:
+	@KenneyNL

internal/web/static/js/casino-sfx.js

@@ -1,12 +1,18 @@
 // The noise the room makes.
 //
-// There are no audio files here and there is nothing to download. Every sound in
+// The room speaks in two voices. The cards and chips are *recorded* — real clay
-// this casino is *made* — an oscillator, a burst of filtered noise, an envelope —
+// and real card stock, CC0 foley from Kenney's casino pack, sitting as small ogg
-// the same bargain the weather engine takes with its clouds. A card is a short
+// files under /static/audio/casino. Synthesis never quite caught the grain of a
-// slap of noise through a bandpass; a chip is two detuned sines with a click on
+// chip landing on a chip, so for those we stopped trying. Everything melodic —
-// the front; a win is four notes going up. It costs about six kilobytes and no
+// the wins, the losses, the little ticks — is still *made*: an oscillator, a
-// round trips, and it means a sound can be pitched, stretched and detuned per
+// burst of filtered noise, an envelope, the same bargain the weather engine takes
-// call instead of being the same wav 300 times.
+// with its clouds. A win is four notes going up; a chip is a recording of a chip.
+//
+// A name is a recording if it appears in SAMPLES and synthesised if it appears in
+// SOUNDS. The recordings guard against the one weakness of a sample — the same wav
+// 300 times is a machine gun — by keeping several takes per sound and rotating
+// through them, and by nudging every play a few percent off pitch. The synthesised
+// half was always immune to that; it varies itself.
 //
 // Two rules hold the whole file up.
 //
@@ -21,6 +27,10 @@
 // default-off switch for the entire file, checked before anything else happens.
 //
 // Exposed as window.PeteSFX. Nothing in here knows what blackjack is.
+//
+// If a recording hasn't finished decoding on the frame it's first needed, that one
+// call falls through to the synthesised version — so the table is never silent
+// while the ogg loads, and by the second card everything is real.
 (function () {
   "use strict";
 
@@ -108,6 +118,82 @@
     src.stop(t0 + (o.attack || 0.003) + (o.decay || 0.09) + 0.02);
   }
 
+  // ---- the recordings --------------------------------------------------------
+  //
+  // The foley. Each name maps to a handful of takes; `v` (the index of the card or
+  // chip in a run) picks which one and how far off pitch it lands, so a dealt hand
+  // is four different cards rather than one card four times. `gain` is per-sound
+  // and multiplies the master, exactly like the synthesised sounds' peak does.
+
+  var SAMPLE_BASE = "/static/audio/casino/";
+  var SAMPLES = {
+    // A card thrown down onto the table.
+    card:    { files: ["cardPlace1", "cardPlace2", "cardPlace3", "cardPlace4"], gain: 0.6, vary: 0.04 },
+    // A card slid into place — softer, longer than a throw.
+    deal:    { files: ["cardSlide1", "cardSlide2", "cardSlide3", "cardSlide4", "cardSlide5", "cardSlide6"], gain: 0.5, vary: 0.05 },
+    // A card flicked over.
+    flip:    { files: ["cardFan1", "cardFan2"], gain: 0.5, vary: 0.04 },
+    // The riffle.
+    shuffle: { files: ["cardShuffle"], gain: 0.6 },
+    // A clay chip set down on a stack.
+    chip:    { files: ["chipLay1", "chipLay2", "chipLay3"], gain: 0.6, vary: 0.05 },
+    // Chips gathered and slid away.
+    sweep:   { files: ["chipsHandle2", "chipsHandle4", "chipsHandle6"], gain: 0.5, vary: 0.03 },
+  };
+
+  // Decoded buffers by filename. A value of null means "claimed, in flight or
+  // decoding"; false means "we tried and it failed, never bother again"; an
+  // AudioBuffer means ready.
+  var buffers = {};
+  var warmed = false;
+
+  // decode fetches a file and turns it into a buffer, exactly once per filename.
+  // decodeAudioData exists in a modern promise flavour and an old callback one;
+  // this handles both so the foley works on older Safari too.
+  function decode(file) {
+    if (file in buffers) return; // ready, in flight, or known-bad
+    buffers[file] = null;
+    fetch(SAMPLE_BASE + file + ".ogg")
+      .then(function (r) { return r.ok ? r.arrayBuffer() : Promise.reject(); })
+      .then(function (ab) {
+        return new Promise(function (res, rej) {
+          var p = ctx.decodeAudioData(ab, res, rej);
+          if (p && p.then) p.then(res, rej);
+        });
+      })
+      .then(function (buf) { buffers[file] = buf; })
+      .catch(function () { buffers[file] = false; });
+  }
+
+  // warm pulls every take down once the context is awake, so that after the first
+  // click the whole set is decoded and ready and nothing has to fall back.
+  function warm() {
+    if (warmed || !ctx) return;
+    warmed = true;
+    for (var name in SAMPLES) SAMPLES[name].files.forEach(decode);
+  }
+
+  // sample plays one recorded take. It returns false — rather than making a noise —
+  // when the name isn't a recording or its buffer isn't decoded yet, which is the
+  // caller's signal to reach for the synthesised version instead.
+  function sample(name, t0, v) {
+    var cfg = SAMPLES[name];
+    if (!cfg) return false;
+    var i = Math.abs(Math.round(v));
+    var buf = buffers[cfg.files[i % cfg.files.length]];
+    if (!buf) return false; // not decoded yet, or failed: let synth cover it
+    var src = ctx.createBufferSource();
+    src.buffer = buf;
+    // A few percent off pitch, spread across a small range keyed to v, so a run of
+    // the same sound never reads as a loop.
+    if (cfg.vary) src.playbackRate.value = 1 + (((i % 5) - 2) * cfg.vary);
+    var g = ctx.createGain();
+    g.gain.value = cfg.gain == null ? 0.6 : cfg.gain;
+    src.connect(g).connect(master);
+    src.start(t0);
+    return true;
+  }
+
   // ---- the sounds ------------------------------------------------------------
   //
   // Each one takes the time it starts at, and a `v` — a small per-call variation,
@@ -217,6 +303,7 @@
   // gesture — after which play() can schedule freely.
   function wake() {
     if (ctx && ctx.state === "suspended") ctx.resume().catch(function () {});
+    warm();
   }
   ["pointerdown", "keydown", "touchstart"].forEach(function (ev) {
     window.addEventListener(ev, wake, { passive: true });
@@ -231,13 +318,18 @@
   // lands in 400ms can say so rather than sleeping.
   function play(name, opts) {
     if (muted) return;
-    var s = SOUNDS[name];
+    if (!SOUNDS[name] && !SAMPLES[name]) return; // known to neither voice
-    if (!s) return;
     if (!boot()) return;
     wake();
     if (ctx.state !== "running") return; // not yet touched: no sound, and no error
+    var t0 = ctx.currentTime + ((opts && opts.delay) || 0);
+    var v = (opts && opts.v) || 0;
     try {
-      s(ctx.currentTime + ((opts && opts.delay) || 0), ((opts && opts.v) || 0));
+      // A recording if we have one decoded; the synthesised take otherwise — both
+      // for names that are only ever synthesised, and for the first call of a
+      // recorded name while its ogg is still loading.
+      if (sample(name, t0, v)) return;
+      if (SOUNDS[name]) SOUNDS[name](t0, v);
     } catch (e) {
       /* a sound is never worth throwing over */
     }