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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>ROT-1 — MIDI Corruptor</title>
<link rel="preconnect" href="https://fonts.googleapis.com">
<link href="https://fonts.googleapis.com/css2?family=Unica+One&family=JetBrains+Mono:wght@400;500;700&display=swap" rel="stylesheet">
<style>
:root{
--panel:#121419;
--raised:#1a1d25;
--inset:#0c0e12;
--line:#2a2e3a;
--amber:#ffb454;
--amber-dim:#9a763e;
--rot:#ff4d6d;
--rot-dim:#7a2b3c;
--cream:#d6d1c2;
--dim:#6b7080;
--teal:#6fd3c7;
--mono:'JetBrains Mono',ui-monospace,Menlo,Consolas,monospace;
--disp:'Unica One',var(--mono);
}
*{box-sizing:border-box;margin:0;padding:0}
html,body{background:var(--panel);color:var(--cream);font-family:var(--mono);font-size:13px;line-height:1.5}
body{padding:14px;max-width:1180px;margin:0 auto}
/* ---------- faceplate header ---------- */
header{
display:flex;align-items:baseline;justify-content:space-between;gap:16px;flex-wrap:wrap;
border:1px solid var(--line);border-radius:8px;background:linear-gradient(180deg,#1c1f28,#15171e);
padding:14px 18px;margin-bottom:14px;
}
.brand{display:flex;align-items:baseline;gap:14px;flex-wrap:wrap}
h1{font-family:var(--disp);font-weight:400;font-size:30px;letter-spacing:.12em;color:var(--cream)}
h1 .rot{color:var(--rot)}
.tagline{color:var(--dim);font-size:11.5px;letter-spacing:.04em}
.seedbox{display:flex;align-items:center;gap:10px}
.seedbox .lbl{font-size:10px;letter-spacing:.18em;color:var(--dim)}
.seedval{
font-size:14px;color:var(--amber);background:var(--inset);border:1px solid var(--line);
border-radius:4px;padding:4px 10px;min-width:96px;text-align:center;
text-shadow:0 0 8px rgba(255,180,84,.45);
}
/* ---------- layout ---------- */
.grid{display:grid;grid-template-columns:300px 1fr;gap:14px}
@media(max-width:840px){.grid{grid-template-columns:1fr}}
.panel{border:1px solid var(--line);border-radius:8px;background:var(--raised);padding:14px}
.panel h2{
font-family:var(--disp);font-weight:400;font-size:13px;letter-spacing:.22em;
color:var(--dim);margin-bottom:10px;text-transform:uppercase;
}
/* ---------- file deck ---------- */
#drop{
border:1.5px dashed var(--line);border-radius:6px;background:var(--inset);
padding:22px 12px;text-align:center;cursor:pointer;transition:border-color .15s,background .15s;
color:var(--dim);
}
#drop:hover,#drop.over{border-color:var(--amber);color:var(--amber)}
#drop strong{color:var(--cream);display:block;margin-bottom:4px;font-weight:500}
#drop.over strong{color:var(--amber)}
.deckrow{display:flex;gap:8px;margin-top:10px}
button{
font-family:var(--mono);font-size:12px;letter-spacing:.04em;cursor:pointer;
background:var(--inset);color:var(--cream);border:1px solid var(--line);border-radius:5px;
padding:8px 10px;transition:border-color .12s,color .12s,background .12s;flex:1;
}
button:hover{border-color:var(--amber);color:var(--amber)}
button:focus-visible{outline:2px solid var(--amber);outline-offset:1px}
button:disabled{opacity:.35;cursor:default;pointer-events:none}
button.hot{border-color:var(--rot-dim);color:var(--rot)}
button.hot:hover{border-color:var(--rot);background:rgba(255,77,109,.08)}
button.playing{border-color:var(--amber);color:var(--amber);background:rgba(255,180,84,.08)}
#stats{margin-top:12px;font-size:11.5px;color:var(--dim);display:grid;grid-template-columns:auto 1fr;gap:2px 12px}
#stats b{color:var(--cream);font-weight:500;text-align:right}
#stats b.rotv{color:var(--rot)}
#stats b.okv{color:var(--teal)}
#fileline{margin-top:10px;font-size:11px;color:var(--teal);min-height:16px;word-break:break-all}
/* ---------- piano roll ---------- */
.rollwrap{position:relative;background:var(--inset);border:1px solid var(--line);border-radius:6px;overflow:hidden}
canvas{display:block;width:100%}
#overlay{position:absolute;inset:0;pointer-events:none}
.legend{display:flex;gap:18px;margin-top:8px;font-size:11px;color:var(--dim);flex-wrap:wrap}
.legend span{display:inline-flex;align-items:center;gap:6px}
.chip{width:14px;height:8px;border-radius:2px;display:inline-block}
.chip.ghost{background:rgba(255,180,84,.3);border:1px solid rgba(255,180,84,.4)}
.chip.live{background:var(--rot);box-shadow:0 0 6px rgba(255,77,109,.6)}
/* ---------- fader bank ---------- */
.faders{display:grid;grid-template-columns:1fr 1fr;gap:8px 22px;margin-top:2px}
@media(max-width:640px){.faders{grid-template-columns:1fr}}
.fader{display:grid;grid-template-columns:118px 1fr 44px;align-items:center;gap:10px;padding:5px 0}
.fader label{font-size:11px;letter-spacing:.06em;color:var(--cream)}
.fader .sub{display:block;font-size:9.5px;color:var(--dim);letter-spacing:.02em}
.fader output{
font-size:12px;color:var(--amber);background:var(--inset);border:1px solid var(--line);
border-radius:4px;padding:3px 0;text-align:center;text-shadow:0 0 6px rgba(255,180,84,.35);
}
input[type=range]{-webkit-appearance:none;appearance:none;width:100%;height:22px;background:transparent;cursor:pointer}
input[type=range]:focus-visible{outline:2px solid var(--amber);outline-offset:2px;border-radius:4px}
input[type=range]::-webkit-slider-runnable-track{height:4px;border-radius:2px;background:linear-gradient(90deg,var(--amber-dim),var(--rot));opacity:.85}
input[type=range]::-webkit-slider-thumb{
-webkit-appearance:none;width:10px;height:20px;margin-top:-8px;border-radius:2px;
background:linear-gradient(180deg,#e8e2d2,#a09a89);border:1px solid #000;
box-shadow:0 1px 3px rgba(0,0,0,.7);
}
input[type=range]::-moz-range-track{height:4px;border-radius:2px;background:linear-gradient(90deg,var(--amber-dim),var(--rot));opacity:.85}
input[type=range]::-moz-range-thumb{width:10px;height:20px;border-radius:2px;background:linear-gradient(180deg,#e8e2d2,#a09a89);border:1px solid #000}
.bankhead{display:flex;justify-content:space-between;align-items:center;margin-bottom:6px;gap:10px;flex-wrap:wrap}
.bankhead h2{margin-bottom:0}
.bankhead .actions{display:flex;gap:8px}
.bankhead button{flex:none;padding:6px 14px}
/* ---------- log ---------- */
#log{
background:var(--inset);border:1px solid var(--line);border-radius:6px;
height:148px;overflow-y:auto;padding:8px 10px;font-size:11px;line-height:1.7;
}
#log .t{display:inline-block;width:52px;color:var(--dim)}
#log .t.pitch{color:var(--rot)}
#log .t.vel{color:var(--amber)}
#log .t.tempo{color:var(--teal)}
#log .t.prog{color:var(--teal)}
#log .t.drop{color:var(--dim)}
#log .t.time{color:var(--amber-dim)}
#log .drop-line{color:var(--dim);text-decoration:line-through}
#log .empty{color:var(--dim);font-style:italic}
footer{margin-top:14px;text-align:center;font-size:10.5px;color:var(--dim);letter-spacing:.05em}
@media(prefers-reduced-motion:no-preference){
.seedval.flash{animation:flash .35s ease}
@keyframes flash{0%{color:var(--rot);text-shadow:0 0 12px rgba(255,77,109,.8)}100%{color:var(--amber)}}
}
.stack{display:flex;flex-direction:column;gap:14px}
</style>
</head>
<body>
<header>
<div class="brand">
<h1>ROT<span class="rot">-1</span> MIDI CORRUPTOR</h1>
<div class="tagline">format-aware byte rot</div>
</div>
<div class="seedbox">
<span class="lbl">SEED</span>
<span class="seedval" id="seedval">0x0000</span>
</div>
</header>
<div class="grid">
<div class="stack">
<section class="panel">
<h2>File deck</h2>
<div id="drop" role="button" tabindex="0" aria-label="Load a MIDI file">
<strong>Drop a .mid file here</strong>
or click to browse
</div>
<input type="file" id="file" accept=".mid,.midi,audio/midi" hidden>
<div class="deckrow">
<button id="demo">Load demo loop</button>
</div>
<div id="fileline"></div>
<div id="stats"></div>
</section>
<section class="panel">
<h2>Transport</h2>
<div class="deckrow" style="margin-top:0">
<button id="playOrig" disabled>▶ Original</button>
<button id="playRot" class="hot" disabled>▶ Corrupted</button>
<button id="stop" disabled>■ Stop</button>
</div>
<div class="deckrow">
<button id="download" class="hot" disabled>⬇ Download corrupted .mid</button>
</div>
</section>
</div>
<div class="stack">
<section class="panel">
<h2>Decay overlay</h2>
<div class="rollwrap">
<canvas id="roll" height="300"></canvas>
<canvas id="overlay" height="300"></canvas>
</div>
<div class="legend">
<span><span class="chip ghost"></span> original (ghost)</span>
<span><span class="chip live"></span> corrupted (current state)</span>
<span id="durline"></span>
</div>
</section>
<section class="panel">
<div class="bankhead">
<h2>Corruption bank</h2>
<div class="actions">
<button id="reroll" class="hot" disabled>↻ Re-roll seed</button>
<button id="reset" disabled>Zero all</button>
</div>
</div>
<div class="faders" id="faders"></div>
</section>
</div>
</div>
<section class="panel" style="margin-top:14px">
<h2>Rot log</h2>
<div id="log"><span class="empty">Load a file and push a fader. Every mutation gets reported here.</span></div>
</section>
<footer>ROT-1 · runs entirely in your browser · nothing is uploaded anywhere · <a href="https://github.com/RandomTypek/ROT-1" target="_blank" rel="noopener">source on GitHub</a></footer>
<script>
'use strict';
/* ============================================================
ENGINE — parse / corrupt / serialize Standard MIDI Files
============================================================ */
function mulberry32(seed){let a=seed>>>0;return function(){a|=0;a=(a+0x6D2B79F5)|0;let t=Math.imul(a^(a>>>15),1|a);t=(t+Math.imul(t^(t>>>7),61|t))^t;return((t^(t>>>14))>>>0)/4294967296;};}
function clamp(v,lo,hi){return v<lo?lo:v>hi?hi:v}
function irnd(rnd,lo,hi){return lo+Math.floor(rnd()*(hi-lo+1))}
function parseMidi(bytes){
const data=bytes instanceof Uint8Array?bytes:new Uint8Array(bytes);
let pos=0;
function u32(){const v=(data[pos]<<24)|(data[pos+1]<<16)|(data[pos+2]<<8)|data[pos+3];pos+=4;return v>>>0}
function u16(){const v=(data[pos]<<8)|data[pos+1];pos+=2;return v}
function u8(){return data[pos++]}
function vlq(){let v=0,b;do{b=u8();v=(v<<7)|(b&0x7f)}while(b&0x80);return v}
if(u32()!==0x4D546864)throw new Error('Not a MIDI file — missing MThd header');
const hlen=u32(),format=u16(),ntrks=u16(),division=u16();
pos+=hlen-6;
const tracks=[];
for(let t=0;t<ntrks&&pos<data.length;t++){
if(u32()!==0x4D54726B)throw new Error('Bad track chunk at track '+t);
const len=u32(),end=pos+len,events=[];
let tick=0,runningStatus=0;
while(pos<end){
tick+=vlq();
let status=data[pos];
if(status<0x80){status=runningStatus}else{pos++}
if(status>=0x80&&status<=0xEF)runningStatus=status;
const type=status&0xF0,ch=status&0x0F;
if(status===0xFF){
const metaType=u8(),mlen=vlq();
const payload=data.slice(pos,pos+mlen);pos+=mlen;
events.push({tick,kind:'meta',metaType,data:payload});
}else if(status===0xF0||status===0xF7){
const slen=vlq();
const payload=data.slice(pos,pos+slen);pos+=slen;
events.push({tick,kind:'sysex',status,data:payload});
}else if(type===0xC0||type===0xD0){
events.push({tick,kind:'channel',type,ch,d1:u8()});
}else if(type>=0x80&&type<=0xE0){
const d1=u8(),d2=u8();
const k={tick,kind:'channel',type,ch,d1,d2};
if(type===0x90&&d2===0)k.type=0x80;
events.push(k);
}else{pos=end}
}
pos=end;
tracks.push(events);
}
return{format,division,tracks};
}
function serializeMidi(midi){
const out=[];
const push=(...b)=>{for(const x of b)out.push(x)};
function u32(v){push((v>>>24)&255,(v>>>16)&255,(v>>>8)&255,v&255)}
function u16(v){push((v>>>8)&255,v&255)}
push(0x4D,0x54,0x68,0x64);u32(6);
u16(midi.format);u16(midi.tracks.length);u16(midi.division);
const eotLast=e=>(e.kind==='meta'&&e.metaType===0x2F)?1:0;
for(const events of midi.tracks){
const sorted=events.slice().sort((a,b)=>a.tick-b.tick||eotLast(a)-eotLast(b));
const body=[];
const bp=(...b)=>{for(const x of b)body.push(x)};
const bvlq=v=>{v=Math.max(0,Math.round(v));const st=[v&0x7f];while((v>>=7))st.unshift((v&0x7f)|0x80);bp(...st)};
let last=0,wroteEOT=false;
for(const e of sorted){
if(e.kind==='meta'&&e.metaType===0x2F&&wroteEOT)continue;
bvlq(e.tick-last);last=e.tick;
if(e.kind==='meta'){
bp(0xFF,e.metaType);bvlq(e.data.length);bp(...e.data);
if(e.metaType===0x2F)wroteEOT=true;
}else if(e.kind==='sysex'){
bp(e.status);bvlq(e.data.length);bp(...e.data);
}else{
bp(((e.type===0x80?0x80:e.type)|e.ch),e.d1&0x7f);
if(e.type!==0xC0&&e.type!==0xD0)bp((e.d2??0)&0x7f);
}
}
if(!wroteEOT){bvlq(0);bp(0xFF,0x2F,0x00)}
push(0x4D,0x54,0x72,0x6B);u32(body.length);push(...body);
}
return new Uint8Array(out);
}
const NOTE_NAMES=['C','C#','D','D#','E','F','F#','G','G#','A','A#','B'];
const nn=n=>NOTE_NAMES[n%12]+(Math.floor(n/12)-1);
const GM=['Piano','Chromatic','Organ','Guitar','Bass','Strings','Ensemble','Brass','Reed','Pipe','Synth Lead','Synth Pad','Synth FX','Ethnic','Percussive','FX'];
const gmName=p=>GM[Math.floor(p/8)]+' '+(p%8+1);
function corruptMidi(midi,params,log){
const rnd=mulberry32(params.seed);
const div=midi.division&0x8000?480:midi.division;
const out={format:midi.format,division:midi.division,tracks:[]};
const stats={changed:0,dropped:0,injected:0};
for(let ti=0;ti<midi.tracks.length;ti++){
const src=midi.tracks[ti];
const events=[];
const active=new Map();
let sawProgram=false,sawNotes=false;
for(const e0 of src){
const e=Object.assign({},e0);
if(e.kind==='channel'){
if(e.type===0x90){
sawNotes=true;
const key=e.ch+':'+e.d1;
const rec={newPitch:e.d1,dropped:false};
if(rnd()<params.drop){
rec.dropped=true;stats.dropped++;
if(log)log.push(['drop','note '+nn(e.d1)+' ch'+(e.ch+1)+' deleted @ tick '+e.tick]);
}else{
if(rnd()<params.pitch){
const range=Math.max(2,Math.round(params.pitch*36));
const np=clamp(e.d1+irnd(rnd,-range,range),0,127);
if(np!==e.d1){
if(log)log.push(['pitch','note '+nn(e.d1)+' \u2192 '+nn(np)+' ch'+(e.ch+1)+' @ tick '+e.tick]);
rec.newPitch=np;e.d1=np;stats.changed++;
}
}
if(rnd()<params.velocity){
const nv=1+Math.floor(rnd()*126);
if(log&&Math.abs(nv-e.d2)>25)log.push(['vel','velocity '+e.d2+' \u2192 '+nv+' @ tick '+e.tick]);
e.d2=nv;stats.changed++;
}
}
if(!active.has(key))active.set(key,[]);
active.get(key).push(rec);
if(rec.dropped)continue;
}else if(e.type===0x80){
const key=e.ch+':'+e.d1;
const list=active.get(key);
const rec=list&&list.length?list.shift():null;
if(rec){if(rec.dropped)continue;e.d1=rec.newPitch}
}else if(e.type===0xC0){
sawProgram=true;
if(rnd()<params.instrument){
const np=Math.floor(rnd()*128);
if(log)log.push(['prog',gmName(e.d1)+' \u2192 '+gmName(np)+' ch'+(e.ch+1)+' @ tick '+e.tick]);
e.d1=np;stats.changed++;
}
}
}else if(e.kind==='meta'&&e.metaType===0x51&&e.data.length===3){
if(rnd()<params.tempo){
const us=(e.data[0]<<16)|(e.data[1]<<8)|e.data[2];
const factor=Math.pow(2,(rnd()*2-1)*(1+params.tempo*2));
const nus=clamp(Math.round(us*factor),60000,4000000);
e.data=new Uint8Array([(nus>>16)&255,(nus>>8)&255,nus&255]);
if(log)log.push(['tempo',Math.round(60e6/us)+' \u2192 '+Math.round(60e6/nus)+' BPM @ tick '+e.tick]);
stats.changed++;
}
}
events.push(e);
}
if(!sawProgram&&sawNotes&&rnd()<params.instrument){
const chs=new Set(events.filter(x=>x.kind==='channel'&&x.type===0x90).map(x=>x.ch));
for(const ch of chs){
if(ch===9)continue;
const np=Math.floor(rnd()*128);
events.unshift({tick:0,kind:'channel',type:0xC0,ch,d1:np});
if(log)log.push(['prog','injected '+gmName(np)+' on ch'+(ch+1)]);
stats.injected++;
}
}
if(params.smear>0){
const maxJ=params.smear*div;
const pairs=new Map();
for(const e of events){
if(e.kind!=='channel'||(e.type!==0x90&&e.type!==0x80))continue;
const key=e.ch+':'+e.d1;
if(e.type===0x90){
if(rnd()<Math.min(1,params.smear*1.5)){
const j=Math.round((rnd()*2-1)*maxJ);
if(j!==0){e.tick=Math.max(0,e.tick+j);stats.changed++;if(log&&Math.abs(j)>div/3)log.push(['time','note shifted '+(j>0?'+':'')+j+' ticks'])}
}
if(!pairs.has(key))pairs.set(key,[]);
pairs.get(key).push(e);
}else{
const list=pairs.get(key);
const on=list&&list.length?list.shift():null;
if(on&&rnd()<Math.min(1,params.smear*1.5)){
const j=Math.round((rnd()*2-1)*maxJ);
e.tick=Math.max(on.tick+1,e.tick+j);
}else if(on&&e.tick<=on.tick){
e.tick=on.tick+1;
}
}
}
}
if(ti===0&¶ms.tempo>0.5){
const maxTick=events.reduce((m,e)=>Math.max(m,e.tick),0);
const n=Math.floor((params.tempo-0.5)*8*rnd());
for(let i=0;i<n;i++){
const us=clamp(Math.round(150000+rnd()*1500000),60000,4000000);
events.push({tick:Math.floor(rnd()*maxTick),kind:'meta',metaType:0x51,data:new Uint8Array([(us>>16)&255,(us>>8)&255,us&255])});
if(log)log.push(['tempo','injected lurch to '+Math.round(60e6/us)+' BPM']);
stats.injected++;
}
}
out.tracks.push(events);
}
out._stats=stats;
return out;
}
function extractNotes(midi){
const ppq=midi.division&0x8000?480:midi.division;
let tempos=[];
for(const tr of midi.tracks)for(const e of tr)
if(e.kind==='meta'&&e.metaType===0x51&&e.data.length===3)
tempos.push({tick:e.tick,us:(e.data[0]<<16)|(e.data[1]<<8)|e.data[2]});
tempos.sort((a,b)=>a.tick-b.tick);
if(!tempos.length||tempos[0].tick>0)tempos.unshift({tick:0,us:500000});
let acc=0;
for(let i=0;i<tempos.length;i++){
if(i>0)acc+=(tempos[i].tick-tempos[i-1].tick)*tempos[i-1].us/ppq/1e6;
tempos[i].sec=acc;
}
function tickToSec(tick){
let t=tempos[0];
for(const x of tempos){if(x.tick<=tick)t=x;else break}
return t.sec+(tick-t.tick)*t.us/ppq/1e6;
}
const notes=[],programs=[];
for(const tr of midi.tracks){
const open=new Map();
for(const e of tr){
if(e.kind!=='channel')continue;
if(e.type===0x90){
const key=e.ch+':'+e.d1;
if(!open.has(key))open.set(key,[]);
open.get(key).push({start:tickToSec(e.tick),pitch:e.d1,vel:e.d2,ch:e.ch});
}else if(e.type===0x80){
const key=e.ch+':'+e.d1;
const list=open.get(key);
const n=list&&list.length?list.shift():null;
if(n){n.end=tickToSec(e.tick);if(n.end>n.start)notes.push(n)}
}else if(e.type===0xC0){
programs.push({sec:tickToSec(e.tick),ch:e.ch,prog:e.d1});
}
}
for(const list of open.values())for(const n of list){n.end=n.start+0.5;notes.push(n)}
}
notes.sort((a,b)=>a.start-b.start);
programs.sort((a,b)=>a.sec-b.sec);
const duration=notes.reduce((m,n)=>Math.max(m,n.end),0);
return{notes,programs,duration};
}
function makeDemoMidi(){
const ppq=480;
const t0=[{tick:0,kind:'meta',metaType:0x51,data:new Uint8Array([0x07,0xA1,0x20])}];
const melody=[],bass=[],drums=[];
const scale=[60,62,64,67,69,72,74,76];
let tick=0;
for(let bar=0;bar<8;bar++)for(let i=0;i<8;i++){
const p=scale[(bar*3+i*2)%scale.length];
melody.push({tick,kind:'channel',type:0x90,ch:0,d1:p,d2:90});
melody.push({tick:tick+ppq/2-10,kind:'channel',type:0x80,ch:0,d1:p,d2:0});
tick+=ppq/2;
}
tick=0;
const roots=[48,45,41,43];
for(let bar=0;bar<8;bar++){
const r=roots[bar%4];
bass.push({tick,kind:'channel',type:0x90,ch:1,d1:r,d2:100});
bass.push({tick:tick+ppq*4-20,kind:'channel',type:0x80,ch:1,d1:r,d2:0});
tick+=ppq*4;
}
tick=0;
for(let beat=0;beat<32;beat++){
const d=beat%2===0?36:38;
drums.push({tick,kind:'channel',type:0x90,ch:9,d1:d,d2:110});
drums.push({tick:tick+60,kind:'channel',type:0x80,ch:9,d1:d,d2:0});
drums.push({tick:tick+ppq/2,kind:'channel',type:0x90,ch:9,d1:42,d2:70});
drums.push({tick:tick+ppq/2+40,kind:'channel',type:0x80,ch:9,d1:42,d2:0});
tick+=ppq;
}
melody.unshift({tick:0,kind:'channel',type:0xC0,ch:0,d1:80});
bass.unshift({tick:0,kind:'channel',type:0xC0,ch:1,d1:38});
return{format:1,division:ppq,tracks:[t0,melody,bass,drums]};
}
/* ============================================================
APP STATE
============================================================ */
const FADERS=[
{id:'pitch', label:'PITCH CHAOS', sub:'transpose notes at random'},
{id:'velocity', label:'VELOCITY CHAOS', sub:'dynamics go feral'},
{id:'smear', label:'TIME SMEAR', sub:'jitter note timing'},
{id:'drop', label:'NOTE DECAY', sub:'notes simply vanish'},
{id:'instrument',label:'INSTRUMENT ROULETTE',sub:'reroll GM programs'},
{id:'tempo', label:'TEMPO WARP', sub:'bend + inject tempo events'},
];
let original=null; // parsed midi
let originalBytes=null;
let corrupted=null; // corrupted parsed midi
let corruptedBytes=null;
let origNotes=null,rotNotes=null;
let seed=Math.floor(Math.random()*0xFFFF);
let fileName='untitled.mid';
let logEntries=[];
const $=id=>document.getElementById(id);
const seedEl=$('seedval');
function showSeed(flash){
seedEl.textContent='0x'+seed.toString(16).toUpperCase().padStart(4,'0');
if(flash){seedEl.classList.remove('flash');void seedEl.offsetWidth;seedEl.classList.add('flash')}
}
showSeed(false);
/* ---------- fader bank ---------- */
const fadersEl=$('faders');
for(const f of FADERS){
const row=document.createElement('div');
row.className='fader';
row.innerHTML='<label for="f_'+f.id+'">'+f.label+'<span class="sub">'+f.sub+'</span></label>'+
'<input type="range" id="f_'+f.id+'" min="0" max="100" value="0" step="1" aria-label="'+f.label+'">'+
'<output id="o_'+f.id+'">0</output>';
fadersEl.appendChild(row);
}
let debounceTimer=null;
for(const f of FADERS){
$('f_'+f.id).addEventListener('input',e=>{
$('o_'+f.id).textContent=e.target.value;
clearTimeout(debounceTimer);
debounceTimer=setTimeout(applyCorruption,120);
});
}
function getParams(){
const p={seed};
for(const f of FADERS)p[f.id]=parseInt($('f_'+f.id).value,10)/100;
return p;
}
/* ---------- file loading ---------- */
const drop=$('drop');
drop.addEventListener('click',()=>$('file').click());
drop.addEventListener('keydown',e=>{if(e.key==='Enter'||e.key===' '){e.preventDefault();$('file').click()}});
drop.addEventListener('dragover',e=>{e.preventDefault();drop.classList.add('over')});
drop.addEventListener('dragleave',()=>drop.classList.remove('over'));
drop.addEventListener('drop',e=>{
e.preventDefault();drop.classList.remove('over');
const f=e.dataTransfer.files[0];
if(f)loadFile(f);
});
$('file').addEventListener('change',e=>{if(e.target.files[0])loadFile(e.target.files[0])});
$('demo').addEventListener('click',()=>{
const demo=makeDemoMidi();
originalBytes=serializeMidi(demo);
fileName='rot1-demo-loop.mid';
ingest(originalBytes);
});
function loadFile(f){
fileName=f.name;
const reader=new FileReader();
reader.onload=()=>{
try{ingest(new Uint8Array(reader.result))}
catch(err){$('fileline').textContent='\u26A0 '+err.message;$('fileline').style.color='var(--rot)'}
};
reader.readAsArrayBuffer(f);
}
function ingest(bytes){
stopPlayback();
originalBytes=bytes;
original=parseMidi(bytes);
origNotes=extractNotes(original);
$('fileline').style.color='var(--teal)';
$('fileline').textContent='MThd OK \u00B7 '+fileName;
$('playOrig').disabled=false;
$('reroll').disabled=false;
$('reset').disabled=false;
applyCorruption();
}
/* ---------- corruption pipeline ---------- */
function applyCorruption(){
if(!original)return;
stopPlayback();
logEntries=[];
corrupted=corruptMidi(original,getParams(),logEntries);
corruptedBytes=serializeMidi(corrupted);
rotNotes=extractNotes(corrupted);
$('playRot').disabled=false;
$('download').disabled=false;
renderStats();
renderLog();
drawRoll();
}
function renderStats(){
const s=corrupted._stats;
const ev=original.tracks.reduce((a,t)=>a+t.length,0);
$('stats').innerHTML=
'format<b>'+original.format+'</b>'+
'tracks<b>'+original.tracks.length+'</b>'+
'division<b>'+(original.division&0x8000?'SMPTE':original.division+' PPQ')+'</b>'+
'events<b>'+ev+'</b>'+
'notes<b>'+origNotes.notes.length+' \u2192 '+rotNotes.notes.length+'</b>'+
'bytes<b>'+originalBytes.length+' \u2192 '+corruptedBytes.length+'</b>'+
'mutated<b class="rotv">'+s.changed+'</b>'+
'dropped<b class="rotv">'+s.dropped+'</b>'+
'injected<b class="'+(s.injected?'rotv':'okv')+'">'+s.injected+'</b>';
$('durline').textContent='duration '+origNotes.duration.toFixed(1)+'s \u2192 '+rotNotes.duration.toFixed(1)+'s';
}
function renderLog(){
const el=$('log');
if(!logEntries.length){
el.innerHTML='<span class="empty">'+ (original?'Faders at zero — the file is untouched. Push something.':'Load a file first.') +'</span>';
return;
}
const recent=logEntries.slice(-300).reverse();
el.innerHTML=recent.map(([t,msg])=>
'<div'+(t==='drop'?' class="drop-line"':'')+'><span class="t '+t+'">['+t.toUpperCase()+']</span> '+msg+'</div>'
).join('');
el.scrollTop=0;
}
/* ---------- piano roll ---------- */
const roll=$('roll'),overlay=$('overlay');
function drawRoll(){
const wrap=roll.parentElement;
const W=wrap.clientWidth,H=300;
const dpr=window.devicePixelRatio||1;
for(const c of[roll,overlay]){c.width=W*dpr;c.height=H*dpr;c.style.height=H+'px'}
const g=roll.getContext('2d');
g.setTransform(dpr,0,0,dpr,0,0);
g.clearRect(0,0,W,H);
if(!origNotes)return;
const all=origNotes.notes.concat(rotNotes?rotNotes.notes:[]);
if(!all.length)return;
let lo=127,hi=0;
for(const n of all){if(n.pitch<lo)lo=n.pitch;if(n.pitch>hi)hi=n.pitch}
lo=Math.max(0,lo-2);hi=Math.min(127,hi+2);
const dur=Math.max(origNotes.duration,rotNotes?rotNotes.duration:0,0.001);
const px=s=>s/dur*(W-2)+1;
const py=p=>H-((p-lo)/(hi-lo+1))*(H-4)-3;
const rh=Math.max(2,Math.min(8,(H-4)/(hi-lo+1)-1));
// grid: octave lines
g.strokeStyle='rgba(214,209,194,.05)';
g.lineWidth=1;
for(let p=Math.ceil(lo/12)*12;p<=hi;p+=12){
g.beginPath();g.moveTo(0,py(p)+rh/2);g.lineTo(W,py(p)+rh/2);g.stroke();
}
// ghost originals
g.fillStyle='rgba(255,180,84,.28)';
for(const n of origNotes.notes){
g.fillRect(px(n.start),py(n.pitch),Math.max(1.5,px(n.end)-px(n.start)),rh);
}
// corrupted, hot
if(rotNotes){
g.shadowColor='rgba(255,77,109,.5)';g.shadowBlur=4;
g.fillStyle='#ff4d6d';
for(const n of rotNotes.notes){
g.globalAlpha=.45+(n.vel/127)*.55;
g.fillRect(px(n.start),py(n.pitch),Math.max(1.5,px(n.end)-px(n.start)),rh);
}
g.globalAlpha=1;g.shadowBlur=0;
}
}
window.addEventListener('resize',()=>{drawRoll()});
/* ---------- playback ---------- */
let actx=null,masterGain=null,noiseBuf=null;
let playing=null; // {which, startAt, dur, notes, programs, timer, scheduled}
function audio(){
if(!actx){
actx=new(window.AudioContext||window.webkitAudioContext)();
const comp=actx.createDynamicsCompressor();
masterGain=actx.createGain();masterGain.gain.value=0.28;
masterGain.connect(comp);comp.connect(actx.destination);
const len=actx.sampleRate*1.2;
noiseBuf=actx.createBuffer(1,len,actx.sampleRate);
const d=noiseBuf.getChannelData(0);
for(let i=0;i<len;i++)d[i]=Math.random()*2-1;
}
if(actx.state==='suspended')actx.resume();
return actx;
}
const WAVES=['triangle','sine','square','sawtooth'];
function progAt(programs,ch,sec){
let p=0;
for(const x of programs){if(x.ch===ch&&x.sec<=sec+0.001)p=x.prog;if(x.sec>sec)break}
return p;
}
function scheduleNote(n,programs,when){
const c=audio();
const t0=when,durN=Math.min(n.end-n.start,8);
const vel=(n.vel/127);
if(n.ch===9){ // drums
const src=c.createBufferSource();src.buffer=noiseBuf;
const f=c.createBiquadFilter(),g2=c.createGain();
if(n.pitch<=41){ // kick: sine sweep instead of noise
const o=c.createOscillator(),og=c.createGain();
o.type='sine';
o.frequency.setValueAtTime(130,t0);
o.frequency.exponentialRampToValueAtTime(38,t0+0.12);
og.gain.setValueAtTime(vel,t0);
og.gain.exponentialRampToValueAtTime(0.001,t0+0.22);
o.connect(og);og.connect(masterGain);
o.start(t0);o.stop(t0+0.25);
return;
}else if(n.pitch===42||n.pitch===44||n.pitch===46||n.pitch>=49){
f.type='highpass';f.frequency.value=6000;
g2.gain.setValueAtTime(vel*0.5,t0);
g2.gain.exponentialRampToValueAtTime(0.001,t0+(n.pitch===46||n.pitch>=49?0.45:0.07));
}else{
f.type='bandpass';f.frequency.value=1800;f.Q.value=0.8;
g2.gain.setValueAtTime(vel*0.8,t0);
g2.gain.exponentialRampToValueAtTime(0.001,t0+0.16);
}
src.connect(f);f.connect(g2);g2.connect(masterGain);
src.start(t0);src.stop(t0+0.6);
return;
}
const prog=progAt(programs,n.ch,n.start);
const o=c.createOscillator(),g2=c.createGain();
o.type=WAVES[Math.floor(prog/32)];
o.frequency.value=440*Math.pow(2,(n.pitch-69)/12);
const a=0.008,peak=vel*0.85;
g2.gain.setValueAtTime(0.0001,t0);
g2.gain.linearRampToValueAtTime(peak,t0+a);
g2.gain.setTargetAtTime(peak*0.6,t0+a,0.08);
g2.gain.setTargetAtTime(0.0001,t0+Math.max(a,durN-0.04),0.05);
o.connect(g2);g2.connect(masterGain);
o.start(t0);o.stop(t0+durN+0.4);
}
function play(which){
if(!original)return;
stopPlayback();
const src=which==='orig'?origNotes:rotNotes;
if(!src||!src.notes.length)return;
const c=audio();
const startAt=c.currentTime+0.12;
const state={which,startAt,dur:src.duration,notes:src.notes,programs:src.programs,idx:0};
state.timer=setInterval(()=>{
const horizon=c.currentTime-startAt+0.45;
while(state.idx<state.notes.length&&state.notes[state.idx].start<=horizon){
const n=state.notes[state.idx++];
scheduleNote(n,state.programs,startAt+n.start);
}
if(c.currentTime-startAt>state.dur+0.5)stopPlayback();
},100);
playing=state;
$('stop').disabled=false;
$(which==='orig'?'playOrig':'playRot').classList.add('playing');
rafPlayhead();
}
let rafId=null;
function rafPlayhead(){
const g=overlay.getContext('2d');
const dpr=window.devicePixelRatio||1;
function frame(){
g.setTransform(dpr,0,0,dpr,0,0);
const W=overlay.clientWidth,H=300;
g.clearRect(0,0,W,H);
if(playing&&actx){
const t=actx.currentTime-playing.startAt;
const dur=Math.max(origNotes.duration,rotNotes?rotNotes.duration:0,0.001);
if(t>=0&&t<=dur){
const x=t/dur*(W-2)+1;
g.strokeStyle=playing.which==='orig'?'#ffb454':'#ff4d6d';
g.lineWidth=1.5;
g.beginPath();g.moveTo(x,0);g.lineTo(x,H);g.stroke();
}
rafId=requestAnimationFrame(frame);
}
}
rafId=requestAnimationFrame(frame);
}
function stopPlayback(){
if(playing){clearInterval(playing.timer);playing=null}
if(rafId){cancelAnimationFrame(rafId);rafId=null}
if(actx){
// hard-mute then rebuild master chain to kill scheduled nodes
try{masterGain.gain.cancelScheduledValues(actx.currentTime);masterGain.gain.setValueAtTime(0,actx.currentTime);}catch(e){}
const old=masterGain;
setTimeout(()=>{try{old.disconnect()}catch(e){}},50);
const comp=actx.createDynamicsCompressor();
masterGain=actx.createGain();masterGain.gain.value=0.28;
masterGain.connect(comp);comp.connect(actx.destination);
}
$('stop').disabled=true;
$('playOrig').classList.remove('playing');
$('playRot').classList.remove('playing');
const g=overlay.getContext('2d');
g.setTransform(1,0,0,1,0,0);
g.clearRect(0,0,overlay.width,overlay.height);
}
$('playOrig').addEventListener('click',()=>play('orig'));
$('playRot').addEventListener('click',()=>play('rot'));
$('stop').addEventListener('click',stopPlayback);
/* ---------- controls ---------- */
$('reroll').addEventListener('click',()=>{
seed=Math.floor(Math.random()*0xFFFF);
showSeed(true);
applyCorruption();
});
$('reset').addEventListener('click',()=>{
for(const f of FADERS){$('f_'+f.id).value=0;$('o_'+f.id).textContent='0'}
applyCorruption();
});
$('download').addEventListener('click',()=>{
if(!corruptedBytes)return;
const blob=new Blob([corruptedBytes],{type:'audio/midi'});
const a=document.createElement('a');
a.href=URL.createObjectURL(blob);
a.download=fileName.replace(/\.midi?$/i,'')+'.rot.mid';
document.body.appendChild(a);a.click();a.remove();
setTimeout(()=>URL.revokeObjectURL(a.href),2000);
});
</script>
</body>
</html>