<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      padding: 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      user-select: none;
    }

    .widget-wrap {
      width: 100%;
      max-width: 520px;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    /* Timeline Area */
    .timeline-container {
      position: relative;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 18px 16px 36px;
    }

    .track {
      position: relative;
      height: 48px;
      background: #edf2f7;
      border-radius: 8px;
      overflow: hidden;
      display: flex;
      align-items: center;
    }

    .wave-bg {
      position: absolute;
      inset: 0;
      display: flex;
      align-items: center;
      justify-content: space-around;
      opacity: 0.25;
      pointer-events: none;
    }
    .wave-bar {
      width: 3px;
      background: #64748b;
      border-radius: 2px;
    }

    .marker {
      position: absolute;
      top: 0;
      bottom: 0;
      width: 3px;
      transform: translateX(-50%);
      z-index: 2;
    }
    .marker.b1 {
      left: 15%;
      background: #2563eb;
    }
    .marker.b2 {
      background: #0284c7;
      transition: left 0.05s ease-out;
    }

    .marker-tag {
      position: absolute;
      top: -24px;
      transform: translateX(-50%);
      font-size: 12px;
      font-weight: 700;
      padding: 2px 6px;
      border-radius: 4px;
      white-space: nowrap;
    }
    .marker.b1 .marker-tag {
      left: 50%;
      background: #dbeafe;
      color: #1d4ed8;
    }
    .marker.b2 .marker-tag {
      left: 50%;
      background: #e0f2fe;
      color: #0369a1;
    }

    .marker-time {
      position: absolute;
      bottom: -22px;
      left: 50%;
      transform: translateX(-50%);
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      font-variant-numeric: tabular-nums;
      white-space: nowrap;
    }

    /* Delta Bracket */
    .delta-bracket {
      position: absolute;
      top: 14px;
      height: 20px;
      border: 2px solid #0284c7;
      border-top: none;
      border-radius: 0 0 6px 6px;
      pointer-events: none;
      z-index: 1;
      display: flex;
      align-items: flex-end;
      justify-content: center;
      padding-bottom: 2px;
    }
    .delta-label {
      position: absolute;
      bottom: -16px;
      font-size: 12px;
      font-weight: 800;
      color: #0369a1;
      font-variant-numeric: tabular-nums;
      background: #f8fafc;
      padding: 0 4px;
    }

    /* Interactive Slider Control */
    .slider-row {
      display: flex;
      flex-direction: column;
      gap: 6px;
    }
    .slider-header {
      display: flex;
      justify-content: space-between;
      font-size: 12px;
      font-weight: 700;
      color: #64748b;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }
    input[type="range"] {
      -webkit-appearance: none;
      width: 100%;
      height: 8px;
      border-radius: 4px;
      background: #e2e8f0;
      outline: none;
      cursor: pointer;
    }
    input[type="range"]::-webkit-slider-thumb {
      -webkit-appearance: none;
      width: 24px;
      height: 24px;
      border-radius: 50%;
      background: #0284c7;
      border: 3px solid #ffffff;
      box-shadow: 0 2px 6px rgba(0,0,0,0.2);
      cursor: grab;
      transition: transform 0.1s ease;
    }
    input[type="range"]::-webkit-slider-thumb:active {
      cursor: grabbing;
      transform: scale(1.1);
    }
    input[type="range"]::-moz-range-thumb {
      width: 24px;
      height: 24px;
      border-radius: 50%;
      background: #0284c7;
      border: 3px solid #ffffff;
      box-shadow: 0 2px 6px rgba(0,0,0,0.2);
      cursor: grab;
    }

    /* Math & Output Display */
    .calc-row {
      display: grid;
      grid-template-columns: 1fr auto;
      gap: 12px;
      align-items: center;
    }

    .formula-box {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 12px 16px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      font-size: 15px;
      font-weight: 600;
      color: #334155;
    }

    .fraction {
      display: inline-flex;
      flex-direction: column;
      vertical-align: middle;
      text-align: center;
      padding: 0 4px;
    }
    .fraction-top {
      border-bottom: 2px solid #475569;
      padding-bottom: 2px;
      color: #1e2945;
      font-weight: 700;
    }
    .fraction-bottom {
      padding-top: 2px;
      color: #0284c7;
      font-weight: 800;
      font-variant-numeric: tabular-nums;
    }

    .badge-bpm {
      min-width: 130px;
      height: 64px;
      border-radius: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      box-shadow: 0 4px 12px rgba(0,0,0,0.1);
      transition: background-color 0.15s ease;
    }
    .bpm-val {
      font-size: 24px;
      font-weight: 900;
      line-height: 1;
      font-variant-numeric: tabular-nums;
    }
    .bpm-unit {
      font-size: 11px;
      font-weight: 700;
      letter-spacing: 0.5px;
      opacity: 0.9;
    }
  </style>
</head>
<body>
  <div class="widget-wrap">
    
    <div class="timeline-container">
      <div class="track" id="track">
        <div class="wave-bg" id="waveform"></div>
        
        
        <div class="marker b1" style="left: 15%;">
          <div class="marker-tag">Beat 1</div>
          <div class="marker-time">1.000s</div>
        </div>

        
        <div class="delta-bracket" id="bracket">
          <div class="delta-label" id="deltaLabel">Δt = 0.480s</div>
        </div>

        
        <div class="marker b2" id="markerB2">
          <div class="marker-tag">Beat 2</div>
          <div class="marker-time" id="timeB2">1.480s</div>
        </div>
      </div>
    </div>

    
    <div class="slider-row">
      <div class="slider-header">
        <span>Beat 2 Transient Position</span>
        <span id="sliderValue">1.480s</span>
      </div>
      <input type="range" id="beat2Slider" min="1.300" max="1.700" step="0.005" value="1.480">
    </div>

    
    <div class="calc-row">
      <div class="formula-box">
        <span>BPM =</span>
        <div class="fraction">
          <span class="fraction-top">1 × 60</span>
          <span class="fraction-bottom" id="mathDelta">0.480s</span>
        </div>
        <span>=</span>
      </div>

      <div class="badge-bpm" id="bpmBadge">
        <span class="bpm-val" id="bpmValue">125.0</span>
        <span class="bpm-unit">BPM</span>
      </div>
    </div>
  </div>

  <script>
    // Build dummy waveform bars
    const waveEl = document.getElementById('waveform');
    const heights = [12, 18, 40, 24, 16, 14, 20, 36, 44, 28, 16, 12, 18, 38, 42, 22, 14, 12, 24, 46, 32, 18, 14];
    for (let i = 0; i < 46; i++) {
      const bar = document.createElement('div');
      bar.className = 'wave-bar';
      bar.style.height = (heights[i % heights.length]) + 'px';
      waveEl.appendChild(bar);
    }

    const slider = document.getElementById('beat2Slider');
    const markerB2 = document.getElementById('markerB2');
    const timeB2 = document.getElementById('timeB2');
    const sliderValue = document.getElementById('sliderValue');
    const bracket = document.getElementById('bracket');
    const deltaLabel = document.getElementById('deltaLabel');
    const mathDelta = document.getElementById('mathDelta');
    const bpmValue = document.getElementById('bpmValue');
    const bpmBadge = document.getElementById('bpmBadge');

    // Timeline mapping: 1.000s = 15%, 1.800s = 95% (80% span for 0.8s => 100% per 1.0s)
    const T1 = 1.000;
    const P1 = 15; // percent

    function update(t2) {
      const deltaT = t2 - T1;
      const bpm = (60 / deltaT);

      // Percentage position of Beat 2
      // 1.0s -> 15%, 1.7s -> 15 + 0.7 * 100 = 85%
      const p2 = P1 + (deltaT / 0.800) * 75;

      markerB2.style.left = p2 + '%';
      timeB2.textContent = t2.toFixed(3) + 's';
      sliderValue.textContent = t2.toFixed(3) + 's';

      bracket.style.left = P1 + '%';
      bracket.style.width = (p2 - P1) + '%';
      deltaLabel.textContent = 'Δt = ' + deltaT.toFixed(3) + 's';

      mathDelta.textContent = deltaT.toFixed(3) + 's';
      bpmValue.textContent = bpm.toFixed(1);

      // Color coding: Slower (Blue) -> Medium (Teal/Amber) -> Faster (Orange/Red)
      // BPM ranges from ~85.7 (1.700s) to 200.0 (1.300s)
      // Map BPM 85..200 to Hue (210 -> 10)
      const clampedBpm = Math.min(Math.max(bpm, 85), 200);
      const ratio = (clampedBpm - 85) / (200 - 85); // 0 (slow) to 1 (fast)
      
      // Interpolate hue from 215 (blue) down to 10 (red)
      const hue = 215 - ratio * 205;
      bpmBadge.style.backgroundColor = `hsl(${hue}, 85%, 45%)`;
    }

    slider.addEventListener('input', (e) => {
      update(parseFloat(e.target.value));
    });

    // Initial render
    update(1.480);
  </script>
</body>
</html>

Tempo Mapping: Beat Mapping and Dynamic Tempo Curves

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, sans-serif; }
    body {
      width: 100%;
      background: #ffffff;
      color: #0f172a;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
      user-select: none;
    }

    /* Top Step Control Bar */
    .controls {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      flex-wrap: wrap;
    }
    .tabs {
      display: flex;
      gap: 6px;
      flex: 1;
      min-width: 260px;
    }
    .step-btn {
      flex: 1;
      border: 1px solid #cbd5e1;
      background: #f8fafc;
      border-radius: 8px;
      padding: 8px 6px;
      font-size: 13px;
      font-weight: 700;
      color: #334155;
      cursor: pointer;
      text-align: center;
      transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      white-space: nowrap;
    }
    .step-btn:focus-visible {
      outline: 2px solid #2563eb;
      outline-offset: 1px;
    }
    .step-btn.active {
      background: #eff6ff;
      border-color: #1d4ed8;
      color: #1d4ed8;
      box-shadow: 0 1px 3px rgba(29, 78, 216, 0.15);
    }
    .play-btn {
      border: 1px solid #cbd5e1;
      background: #f8fafc;
      border-radius: 8px;
      padding: 8px 14px;
      font-size: 13px;
      font-weight: 700;
      color: #1e293b;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: background-color 0.2s ease;
    }
    .play-btn:focus-visible {
      outline: 2px solid #2563eb;
    }

    /* DAW Viewport */
    .daw-view {
      position: relative;
      width: 100%;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 10px;
      overflow: hidden;
    }

    /* SVG Layer */
    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    /* Dynamic Transitions */
    .marker-transient {
      transition: opacity 0.35s ease;
    }
    .downbeat-guide {
      transition: opacity 0.35s ease;
    }
    .subdiv-guide {
      transition: opacity 0.35s ease;
    }
    .tempo-curve-group {
      transition: opacity 0.35s ease;
    }
    .tempo-placeholder-group {
      transition: opacity 0.35s ease;
    }

    /* Step Info Banner */
    .step-description {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 12px;
      font-size: 13px;
      color: #1e293b;
      display: flex;
      align-items: center;
      gap: 8px;
      line-height: 1.4;
    }
    .step-desc-badge {
      background: #1d4ed8;
      color: #ffffff;
      font-size: 11px;
      font-weight: 800;
      padding: 2px 7px;
      border-radius: 4px;
      white-space: nowrap;
    }

    /* Legend / Indicator Bar */
    .status-bar {
      display: flex;
      align-items: center;
      justify-content: space-around;
      background: #f1f5f9;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 10px;
      font-size: 12px;
      font-weight: 600;
      color: #1e293b;
      flex-wrap: wrap;
      gap: 8px;
    }
    .legend-item {
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .badge-diamond {
      width: 10px;
      height: 10px;
      background: #d97706;
      border: 1px solid #ffffff;
      transform: rotate(45deg);
      border-radius: 1px;
    }
    .badge-downbeat {
      width: 14px;
      height: 4px;
      background: #1d4ed8;
      border-radius: 2px;
    }
    .badge-subdiv {
      width: 14px;
      height: 4px;
      background: #0891b2;
      border-radius: 2px;
    }
    .badge-tempo {
      width: 14px;
      height: 3px;
      background: #7c3aed;
      border-radius: 2px;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <div class="tabs">
      <button class="step-btn active" id="btn0" onclick="setStep(0)">
        <span>1.</span> Detect Transients
      </button>
      <button class="step-btn" id="btn1" onclick="setStep(1)">
        <span>2.</span> Align Downbeats
      </button>
      <button class="step-btn" id="btn2" onclick="setStep(2)">
        <span>3.</span> Subdivide & Map
      </button>
    </div>
    <button class="play-btn" id="playBtn" onclick="togglePlay()" title="Toggle Auto Advance">⏸ Pause</button>
  </div>

  
  <div class="step-description">
    <span class="step-desc-badge" id="stepBadge">STEP 1</span>
    <span id="stepText">Analyze audio waveform to identify sharp transient attacks (kicks & snares).</span>
  </div>

  
  <div class="daw-view">
    <svg viewBox="0 0 600 300" preserveAspectRatio="xMidYMid meet">
      <defs>
        
        <linearGradient id="tempoGrad" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#7c3aed" stop-opacity="0.3"/>
          <stop offset="100%" stop-color="#7c3aed" stop-opacity="0.02"/>
        </linearGradient>
      </defs>

      
      
      <rect x="0" y="0" width="600" height="42" fill="#f1f5f9" />
      
      <rect x="0" y="42" width="600" height="178" fill="#ffffff" />
      
      <rect x="0" y="220" width="600" height="80" fill="#f8fafc" />

      
      <line x1="0" y1="42" x2="600" y2="42" stroke="#cbd5e1" stroke-width="1.5" />
      <line x1="0" y1="131" x2="600" y2="131" stroke="#f1f5f9" stroke-width="1.5" />
      <line x1="0" y1="220" x2="600" y2="220" stroke="#cbd5e1" stroke-width="1.5" />

      
      <rect x="0" y="0" width="105" height="300" fill="#e2e8f0" />
      <line x1="105" y1="0" x2="105" y2="300" stroke="#cbd5e1" stroke-width="2" />

      
      
      <text x="10" y="26" font-size="11" font-weight="800" fill="#1e293b" letter-spacing="0.5">BAR RULER</text>
      
      
      <text x="10" y="125" font-size="11" font-weight="800" fill="#1e293b" letter-spacing="0.5">LIVE AUDIO</text>
      <text x="10" y="141" font-size="10" font-weight="700" fill="#475569">(RUBATO)</text>
      
      
      <text x="10" y="255" font-size="11" font-weight="800" fill="#1e293b" letter-spacing="0.5">BPM CURVE</text>
      <text x="10" y="271" font-size="9" font-weight="700" fill="#64748b">TEMPO MAP</text>

      
      <line x1="105" y1="258" x2="600" y2="258" stroke="#e2e8f0" stroke-width="1" stroke-dasharray="3,3" />
      <text x="110" y="261" font-size="9" font-weight="700" fill="#64748b">120 BPM</text>

      
      <g id="tempoPlaceholder" class="tempo-placeholder-group" opacity="1">
        <text x="350" y="262" font-size="11" font-weight="600" fill="#64748b" text-anchor="middle">
          Tempo map generates upon subdivision (Step 3)
        </text>
      </g>

      
      <g id="tempoTrack" class="tempo-curve-group" opacity="0">
        
        <path d="M 130,290 L 130,268 L 180,264 L 230,274 L 310,248 L 370,252 L 425,266 L 480,250 L 540,262 L 540,290 Z" fill="url(#tempoGrad)" />
        
        
        <polyline points="130,268 180,264 230,274 310,248 370,252 425,266 480,250 540,262" fill="none" stroke="#7c3aed" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" />
        
        
        
        <circle cx="130" cy="268" r="4" fill="#7c3aed" stroke="#ffffff" stroke-width="1.5" />
        <rect x="116" y="272" width="28" height="14" rx="3" fill="#7c3aed" />
        <text x="130" y="283" font-size="9" font-weight="800" fill="#ffffff" text-anchor="middle">116</text>

        
        <circle cx="310" cy="248" r="4" fill="#7c3aed" stroke="#ffffff" stroke-width="1.5" />
        <rect x="296" y="231" width="28" height="14" rx="3" fill="#7c3aed" />
        <text x="310" y="242" font-size="9" font-weight="800" fill="#ffffff" text-anchor="middle">126</text>

        
        <circle cx="425" cy="266" r="3.5" fill="#7c3aed" stroke="#ffffff" stroke-width="1" />
        <text x="425" y="280" font-size="9" font-weight="700" fill="#7c3aed" text-anchor="middle">117</text>

        
        <circle cx="540" cy="262" r="4" fill="#7c3aed" stroke="#ffffff" stroke-width="1.5" />
        <rect x="526" y="244" width="28" height="14" rx="3" fill="#7c3aed" />
        <text x="540" y="255" font-size="9" font-weight="800" fill="#ffffff" text-anchor="middle">120</text>
      </g>

      
      <g id="waveform">
        
        <line x1="105" y1="131" x2="600" y2="131" stroke="#e2e8f0" stroke-width="1.5" stroke-dasharray="4,4" />
        
        
        <path d="
          M 108,131
          L 118,131 L 130,58 L 136,204 L 145,131
          L 165,131 L 180,68 L 188,194 L 198,131
          L 215,131 L 230,76 L 238,186 L 250,131
          L 290,131 L 310,50 L 318,212 L 330,131
          L 355,131 L 370,80 L 378,182 L 390,131
          L 410,131 L 425,66 L 433,196 L 445,131
          L 465,131 L 480,82 L 488,180 L 500,131
          L 520,131 L 540,54 L 548,208 L 560,131
          L 590,131
        " fill="none" stroke="#475569" stroke-width="2.5" stroke-linejoin="round" />
      </g>

      
      <g id="subdivGuides" class="subdiv-guide" opacity="0">
        
        <line x1="180" y1="36" x2="180" y2="220" stroke="#0891b2" stroke-width="1.5" stroke-dasharray="3,3" />
        <rect x="167" y="10" width="26" height="20" rx="4" fill="#0891b2" />
        <text x="180" y="24" font-size="10" font-weight="800" fill="#ffffff" text-anchor="middle">1.2</text>

        
        <line x1="230" y1="36" x2="230" y2="220" stroke="#0891b2" stroke-width="1.5" stroke-dasharray="3,3" />
        <rect x="217" y="10" width="26" height="20" rx="4" fill="#0891b2" />
        <text x="230" y="24" font-size="10" font-weight="800" fill="#ffffff" text-anchor="middle">1.3</text>

        
        <line x1="370" y1="36" x2="370" y2="220" stroke="#0891b2" stroke-width="1.5" stroke-dasharray="3,3" />
        <rect x="357" y="10" width="26" height="20" rx="4" fill="#0891b2" />
        <text x="370" y="24" font-size="10" font-weight="800" fill="#ffffff" text-anchor="middle">2.2</text>

        
        <line x1="425" y1="36" x2="425" y2="220" stroke="#0891b2" stroke-width="1.5" stroke-dasharray="3,3" />
        <rect x="412" y="10" width="26" height="20" rx="4" fill="#0891b2" />
        <text x="425" y="24" font-size="10" font-weight="800" fill="#ffffff" text-anchor="middle">2.3</text>

        
        <line x1="480" y1="36" x2="480" y2="220" stroke="#0891b2" stroke-width="1.5" stroke-dasharray="3,3" />
        <rect x="467" y="10" width="26" height="20" rx="4" fill="#0891b2" />
        <text x="480" y="24" font-size="10" font-weight="800" fill="#ffffff" text-anchor="middle">2.4</text>
      </g>

      
      <g id="downbeatGuides" class="downbeat-guide" opacity="0">
        
        <line x1="130" y1="36" x2="130" y2="220" stroke="#1d4ed8" stroke-width="2.5" />
        <rect x="115" y="7" width="30" height="26" rx="5" fill="#1d4ed8" />
        <text x="130" y="24" font-size="12" font-weight="800" fill="#ffffff" text-anchor="middle">1.1</text>

        
        <line x1="310" y1="36" x2="310" y2="220" stroke="#1d4ed8" stroke-width="2.5" />
        <rect x="295" y="7" width="30" height="26" rx="5" fill="#1d4ed8" />
        <text x="310" y="24" font-size="12" font-weight="800" fill="#ffffff" text-anchor="middle">2.1</text>

        
        <line x1="540" y1="36" x2="540" y2="220" stroke="#1d4ed8" stroke-width="2.5" />
        <rect x="525" y="7" width="30" height="26" rx="5" fill="#1d4ed8" />
        <text x="540" y="24" font-size="12" font-weight="800" fill="#ffffff" text-anchor="middle">3.1</text>
      </g>

      
      <g id="transientMarkers" class="marker-transient">
        
        <g transform="translate(130, 58)"><polygon points="0,-8 8,0 0,8 -8,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(180, 68)"><polygon points="0,-7 7,0 0,7 -7,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(230, 76)"><polygon points="0,-7 7,0 0,7 -7,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(310, 50)"><polygon points="0,-8 8,0 0,8 -8,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(370, 80)"><polygon points="0,-7 7,0 0,7 -7,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(425, 66)"><polygon points="0,-7 7,0 0,7 -7,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(480, 82)"><polygon points="0,-7 7,0 0,7 -7,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
        
        <g transform="translate(540, 54)"><polygon points="0,-8 8,0 0,8 -8,0" fill="#d97706" stroke="#ffffff" stroke-width="1.5"/></g>
      </g>
    </svg>
  </div>

  
  <div class="status-bar">
    <div class="legend-item">
      <div class="badge-diamond"></div>
      <span>Transient Attack</span>
    </div>
    <div class="legend-item">
      <div class="badge-downbeat"></div>
      <span>Downbeat (1.1, 2.1, 3.1)</span>
    </div>
    <div class="legend-item">
      <div class="badge-subdiv"></div>
      <span>Subdivision (2, 3, 4)</span>
    </div>
    <div class="legend-item">
      <div class="badge-tempo"></div>
      <span>Tempo Curve (BPM)</span>
    </div>
  </div>

  <script>
    let curStep = 0;
    let playing = true;
    let timer = null;

    const stepInfo = [
      { badge: "STEP 1", text: "Detect Transients: Audio envelope is scanned to place markers on sharp attacks." },
      { badge: "STEP 2", text: "Align Downbeats: Link primary measure downbeats (1.1, 2.1, 3.1) to main bar kicks." },
      { badge: "STEP 3", text: "Subdivide & Map BPM: Map inner beats to generate an accurate dynamic rubato tempo curve." }
    ];

    const transients = document.getElementById('transientMarkers');
    const downbeats = document.getElementById('downbeatGuides');
    const subdivs = document.getElementById('subdivGuides');
    const tempoTrack = document.getElementById('tempoTrack');
    const tempoPlaceholder = document.getElementById('tempoPlaceholder');
    const stepBadge = document.getElementById('stepBadge');
    const stepText = document.getElementById('stepText');

    function updateView() {
      // Update buttons
      for (let i = 0; i < 3; i++) {
        document.getElementById('btn' + i).classList.toggle('active', i === curStep);
      }

      // Update descriptions
      stepBadge.textContent = stepInfo[curStep].badge;
      stepText.textContent = stepInfo[curStep].text;

      // Update diagram layers based on step
      if (curStep === 0) {
        transients.style.opacity = '1';
        downbeats.style.opacity = '0';
        subdivs.style.opacity = '0';
        tempoTrack.style.opacity = '0';
        tempoPlaceholder.style.opacity = '1';
      } else if (curStep === 1) {
        transients.style.opacity = '1';
        downbeats.style.opacity = '1';
        subdivs.style.opacity = '0';
        tempoTrack.style.opacity = '0';
        tempoPlaceholder.style.opacity = '1';
      } else if (curStep === 2) {
        transients.style.opacity = '1';
        downbeats.style.opacity = '1';
        subdivs.style.opacity = '1';
        tempoTrack.style.opacity = '1';
        tempoPlaceholder.style.opacity = '0';
      }
    }

    function setStep(s) {
      curStep = s;
      updateView();
    }

    function nextStep() {
      curStep = (curStep + 1) % 3;
      updateView();
    }

    function togglePlay() {
      playing = !playing;
      document.getElementById('playBtn').textContent = playing ? '⏸ Pause' : '▶ Play';
      if (playing) startTimer();
      else clearInterval(timer);
    }

    function startTimer() {
      clearInterval(timer);
      timer = setInterval(() => {
        if (playing) nextStep();
      }, 3500);
    }

    updateView();
    startTimer();
  </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      user-select: none;
    }
    .tabs {
      display: flex;
      gap: 6px;
      width: 100%;
    }
    .tab-btn {
      flex: 1;
      padding: 8px 4px;
      font-size: 13px;
      font-weight: 600;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      background: #f8fafc;
      color: #64748b;
      cursor: pointer;
      text-align: center;
      transition: all 0.2s ease;
    }
    .tab-btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
    }
    .graph-container {
      position: relative;
      width: 100%;
      height: 180px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      overflow: hidden;
    }
    svg {
      width: 100%;
      height: 100%;
      display: block;
    }
    .grid-line {
      stroke: #e2e8f0;
      stroke-width: 1;
    }
    .axis-text {
      font-size: 11px;
      fill: #94a3b8;
      font-weight: 500;
    }
    .tempo-curve {
      fill: none;
      stroke: #2563eb;
      stroke-width: 3;
      stroke-linecap: round;
      stroke-linejoin: round;
    }
    .playhead-line {
      stroke: #ef4444;
      stroke-width: 2;
      stroke-dasharray: 4,2;
    }
    .live-dot {
      fill: #ef4444;
      stroke: #ffffff;
      stroke-width: 2;
    }
    .midi-container {
      width: 100%;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 10px 12px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }
    .lane-label {
      font-size: 12px;
      font-weight: 700;
      color: #475569;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .live-bpm {
      font-size: 13px;
      font-weight: 700;
      color: #2563eb;
      font-variant-numeric: tabular-nums;
    }
    .roll-window {
      position: relative;
      height: 48px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      overflow: hidden;
    }
    .hit-zone {
      position: absolute;
      left: 60px;
      top: 0;
      bottom: 0;
      width: 2px;
      background: #ef4444;
      z-index: 5;
    }
    .hit-flash {
      position: absolute;
      left: 48px;
      top: 11px;
      width: 26px;
      height: 26px;
      border-radius: 50%;
      background: rgba(239, 68, 68, 0.25);
      transform: scale(0);
      pointer-events: none;
      transition: transform 0.1s ease-out, opacity 0.15s ease-out;
      opacity: 0;
      z-index: 6;
    }
    .hit-flash.active {
      transform: scale(1.4);
      opacity: 1;
    }
    .midi-note {
      position: absolute;
      top: 14px;
      height: 20px;
      background: #3b82f6;
      border-radius: 4px;
      border: 1px solid #1d4ed8;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    .controls {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 0 2px;
    }
    .ctrl-btn {
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      color: #334155;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .ctrl-btn:active {
      background: #f1f5f9;
    }
    .desc-text {
      font-size: 12px;
      font-weight: 500;
      color: #64748b;
    }
  </style>
</head>
<body>

  <div class="tabs">
    <button class="tab-btn active" onclick="setMode('step')">Jump / Step</button>
    <button class="tab-btn" onclick="setMode('linear')">Linear Ramp</button>
    <button class="tab-btn" onclick="setMode('scurve')">S-Curve (Rubato)</button>
  </div>

  <div class="graph-container">
    <svg viewBox="0 0 400 180" preserveAspectRatio="none">
      
      <line x1="45" y1="15" x2="45" y2="155" class="grid-line" />
      <line x1="95" y1="15" x2="95" y2="155" class="grid-line" />
      <line x1="145" y1="15" x2="145" y2="155" class="grid-line" />
      <line x1="195" y1="15" x2="195" y2="155" class="grid-line" />
      <line x1="245" y1="15" x2="245" y2="155" class="grid-line" />
      <line x1="295" y1="15" x2="295" y2="155" class="grid-line" />
      <line x1="345" y1="15" x2="345" y2="155" class="grid-line" />
      <line x1="395" y1="15" x2="395" y2="155" class="grid-line" />

      
      
      <line x1="45" y1="20" x2="395" y2="20" class="grid-line" />
      <line x1="45" y1="52.5" x2="395" y2="52.5" class="grid-line" />
      <line x1="45" y1="85" x2="395" y2="85" class="grid-line" />
      <line x1="45" y1="117.5" x2="395" y2="117.5" class="grid-line" />
      <line x1="45" y1="150" x2="395" y2="150" class="grid-line" />

      
      <text x="38" y="24" class="axis-text" text-anchor="end">140</text>
      <text x="38" y="56" class="axis-text" text-anchor="end">120</text>
      <text x="38" y="89" class="axis-text" text-anchor="end">100</text>
      <text x="38" y="121" class="axis-text" text-anchor="end">80</text>
      <text x="38" y="154" class="axis-text" text-anchor="end">60</text>

      
      <text x="45" y="170" class="axis-text" text-anchor="middle">Bar 1</text>
      <text x="145" y="170" class="axis-text" text-anchor="middle">Bar 3</text>
      <text x="245" y="170" class="axis-text" text-anchor="middle">Bar 5</text>
      <text x="345" y="170" class="axis-text" text-anchor="middle">Bar 7</text>
      <text x="395" y="170" class="axis-text" text-anchor="middle">Bar 8</text>

      
      <path id="tempoPath" class="tempo-curve" d="" />

      
      <line id="graphPlayhead" x1="45" y1="15" x2="45" y2="155" class="playhead-line" />
      <circle id="graphDot" cx="45" cy="101" r="5" class="live-dot" />
    </svg>
  </div>

  <div class="midi-container">
    <div class="lane-label">
      <span>MIDI Beat Playback</span>
      <span class="live-bpm" id="liveBpm">90.0 BPM</span>
    </div>
    <div class="roll-window" id="rollWindow">
      <div class="hit-zone"></div>
      <div class="hit-flash" id="hitFlash"></div>
      <div id="notesLayer"></div>
    </div>
  </div>

  <div class="controls">
    <span class="desc-text" id="curveDesc">Instant jump at Bar 4 (90 → 120 BPM)</span>
    <button class="ctrl-btn" onclick="togglePlay()">
      <span id="playIcon">⏸</span> <span id="playLabel">Pause</span>
    </button>
  </div>

  <script>
    let mode = 'step';
    let isPlaying = true;
    let currentBeat = 0; // 0 to 32 (8 bars * 4 beats)
    const totalBeats = 32;
    let lastTimestamp = null;
    let lastTriggeredQuarter = -1;

    const descriptions = {
      step: "Instant step at Bar 4 (90 → 120 BPM)",
      linear: "Constant acceleration (70 → 130 BPM)",
      scurve: "Rubato dip & recovery (120 → 72 → 120 BPM)"
    };

    function getBPMAtBeat(b, m) {
      if (m === 'step') {
        return b < 12 ? 90 : 120;
      } else if (m === 'linear') {
        return 70 + (b / 32) * 60;
      } else if (m === 'scurve') {
        const rad = (b / 32) * 2 * Math.PI;
        return 96 - 24 * Math.cos(rad);
      }
      return 120;
    }

    function bpmToY(bpm) {
      // 140 bpm -> y=20, 60 bpm -> y=150
      return 20 + ((140 - bpm) / 80) * 130;
    }

    function beatToX(b) {
      // Bar 1 (b=0) -> x=45, Bar 8 (b=32) -> x=395 (width 350)
      return 45 + (b / 32) * 350;
    }

    function drawCurve() {
      const pathEl = document.getElementById('tempoPath');
      let d = '';
      if (mode === 'step') {
        const x0 = beatToX(0), y0 = bpmToY(90);
        const xStep = beatToX(12);
        const y1 = bpmToY(120);
        const xEnd = beatToX(32);
        d = `M ${x0} ${y0} L ${xStep} ${y0} L ${xStep} ${y1} L ${xEnd} ${y1}`;
      } else {
        const points = [];
        for (let b = 0; b <= 32; b += 0.5) {
          const x = beatToX(b);
          const y = bpmToY(getBPMAtBeat(b, mode));
          points.push(`${b === 0 ? 'M' : 'L'} ${x.toFixed(1)} ${y.toFixed(1)}`);
        }
        d = points.join(' ');
      }
      pathEl.setAttribute('d', d);
      document.getElementById('curveDesc').textContent = descriptions[mode];
    }

    function renderNotes() {
      const layer = document.getElementById('notesLayer');
      layer.innerHTML = '';
      const pixelsPerBeat = 80;
      const hitX = 60;

      for (let b = 0; b < totalBeats; b++) {
        const note = document.createElement('div');
        note.className = 'midi-note';
        note.id = `note-${b}`;
        const width = 36;
        note.style.width = width + 'px';
        const left = hitX + (b - currentBeat) * pixelsPerBeat;
        note.style.transform = `translateX(${left}px)`;
        layer.appendChild(note);
      }
    }

    function setMode(newMode) {
      mode = newMode;
      const buttons = document.querySelectorAll('.tab-btn');
      buttons.forEach(btn => btn.classList.remove('active'));
      if (newMode === 'step') buttons[0].classList.add('active');
      if (newMode === 'linear') buttons[1].classList.add('active');
      if (newMode === 'scurve') buttons[2].classList.add('active');
      drawCurve();
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      document.getElementById('playIcon').textContent = isPlaying ? '⏸' : '▶';
      document.getElementById('playLabel').textContent = isPlaying ? 'Pause' : 'Play';
      if (isPlaying) {
        lastTimestamp = null;
        requestAnimationFrame(loop);
      }
    }

    function triggerHit() {
      const flash = document.getElementById('hitFlash');
      flash.classList.add('active');
      setTimeout(() => flash.classList.remove('active'), 120);
    }

    function loop(timestamp) {
      if (!isPlaying) return;

      if (!lastTimestamp) lastTimestamp = timestamp;
      const dt = (timestamp - lastTimestamp) / 1000;
      lastTimestamp = timestamp;

      const currentBpm = getBPMAtBeat(currentBeat, mode);
      const beatsPerSec = currentBpm / 60;
      currentBeat += beatsPerSec * dt;

      if (currentBeat >= totalBeats) {
        currentBeat = 0;
        lastTriggeredQuarter = -1;
      }

      // Check beat triggers
      const currentQuarter = Math.floor(currentBeat);
      if (currentQuarter !== lastTriggeredQuarter && currentQuarter >= 0) {
        triggerHit();
        lastTriggeredQuarter = currentQuarter;
      }

      // Update Live UI
      document.getElementById('liveBpm').textContent = currentBpm.toFixed(1) + ' BPM';

      // Update Graph Tracking
      const gx = beatToX(currentBeat);
      const gy = bpmToY(currentBpm);
      document.getElementById('graphPlayhead').setAttribute('x1', gx);
      document.getElementById('graphPlayhead').setAttribute('x2', gx);
      document.getElementById('graphDot').setAttribute('cx', gx);
      document.getElementById('graphDot').setAttribute('cy', gy);

      // Update MIDI Note positions
      const pixelsPerBeat = 80;
      const hitX = 60;
      for (let b = 0; b < totalBeats; b++) {
        const noteEl = document.getElementById(`note-${b}`);
        if (noteEl) {
          const left = hitX + (b - currentBeat) * pixelsPerBeat;
          noteEl.style.transform = `translateX(${left}px)`;
          if (left < -50 || left > 500) {
            noteEl.style.display = 'none';
          } else {
            noteEl.style.display = 'block';
          }
        }
      }

      requestAnimationFrame(loop);
    }

    // Init
    drawCurve();
    renderNotes();
    requestAnimationFrame(loop);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, sans-serif; }
    body {
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .controls {
      display: flex;
      justify-content: center;
      gap: 8px;
      flex-wrap: wrap;
    }

    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #1e2945;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 6px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    .btn:hover { background: #f1f5f9; }
    .btn.active {
      background: #3b82f6;
      border-color: #3b82f6;
      color: #ffffff;
    }

    .panels-container {
      display: grid;
      grid-template-columns: 1fr;
      gap: 12px;
    }

    @media (min-width: 580px) {
      .panels-container {
        grid-template-columns: 1fr 1fr;
      }
    }

    .panel {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .panel-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .title {
      font-weight: 700;
      font-size: 14px;
    }

    .badge {
      font-size: 11px;
      font-weight: 700;
      padding: 2px 6px;
      border-radius: 4px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }
    .badge-warp { background: #fee2e2; color: #dc2626; border: 1px solid #fecaca; }
    .badge-map { background: #dcfce7; color: #15803d; border: 1px solid #bbf7d0; }

    .track-view {
      position: relative;
      width: 100%;
      height: 110px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 6px;
      overflow: hidden;
    }

    svg {
      width: 100%;
      height: 100%;
      display: block;
    }

    .status-text {
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      display: flex;
      align-items: center;
      gap: 4px;
    }
  </style>
</head>
<body>

  <div class="controls">
    <button id="btnPlayWarp" class="btn" onclick="playWarpDemo()">▶ Warped (Rigid 120 BPM)</button>
    <button id="btnPlayMap" class="btn" onclick="playMapDemo()">▶ Beat Mapped (Live Groove)</button>
  </div>

  <div class="panels-container">
    
    <div class="panel">
      <div class="panel-header">
        <span class="title">A. Audio Warping</span>
        <span class="badge badge-warp">Alters Audio</span>
      </div>
      <div class="track-view">
        <svg viewBox="0 0 300 110" preserveAspectRatio="none">
          
          <rect x="0" y="0" width="300" height="20" fill="#f1f5f9" />
          <text x="150" y="14" font-size="10" fill="#64748b" font-weight="700" text-anchor="middle">CONSTANT: 120 BPM</text>

          
          <line x1="30" y1="0" x2="30" y2="110" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
          <line x1="105" y1="0" x2="105" y2="110" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
          <line x1="180" y1="0" x2="180" y2="110" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
          <line x1="255" y1="0" x2="255" y2="110" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />

          
          <text x="30" y="30" font-size="9" fill="#94a3b8" font-weight="700" text-anchor="middle">1.1</text>
          <text x="105" y="30" font-size="9" fill="#94a3b8" font-weight="700" text-anchor="middle">1.2</text>
          <text x="180" y="30" font-size="9" fill="#94a3b8" font-weight="700" text-anchor="middle">1.3</text>
          <text x="255" y="30" font-size="9" fill="#94a3b8" font-weight="700" text-anchor="middle">1.4</text>

          
          
          <line x1="0" y1="70" x2="300" y2="70" stroke="#cbd5e1" stroke-width="1" />

          
          <path d="M 15 70 Q 25 70 28 42 L 30 35 L 32 42 Q 35 70 50 70" fill="#3b82f6" opacity="0.75" />
          <path d="M 85 70 Q 100 70 103 45 L 105 38 L 107 45 Q 112 70 130 70" fill="#3b82f6" opacity="0.75" />
          <path d="M 160 70 Q 175 70 178 40 L 180 34 L 182 40 Q 188 70 205 70" fill="#3b82f6" opacity="0.75" />
          <path d="M 235 70 Q 250 70 253 44 L 255 37 L 257 44 Q 262 70 280 70" fill="#3b82f6" opacity="0.75" />

          
          <polygon points="30,70 26,62 34,62" fill="#ef4444" />
          <polygon points="105,70 101,62 109,62" fill="#ef4444" />
          <polygon points="180,70 176,62 184,62" fill="#ef4444" />
          <polygon points="255,70 251,62 259,62" fill="#ef4444" />

          
          <line id="playheadWarp" x1="0" y1="0" x2="0" y2="110" stroke="#ef4444" stroke-width="2" opacity="0" />
        </svg>
      </div>
      <div class="status-text">
        <span style="color:#ef4444;">●</span> Audio stretched • Destroys natural feel
      </div>
    </div>

    
    <div class="panel">
      <div class="panel-header">
        <span class="title">B. Beat Mapping</span>
        <span class="badge badge-map">Alters Grid</span>
      </div>
      <div class="track-view">
        <svg viewBox="0 0 300 110" preserveAspectRatio="none">
          
          <rect x="0" y="0" width="300" height="20" fill="#ecfdf5" />
          <path d="M 0 10 L 30 10 L 95 6 L 192 14 L 265 9 L 300 10" fill="none" stroke="#10b981" stroke-width="1.5" />
          <text x="30" y="14" font-size="8" fill="#047857" font-weight="700" text-anchor="middle">120</text>
          <text x="95" y="14" font-size="8" fill="#047857" font-weight="700" text-anchor="middle">126</text>
          <text x="192" y="14" font-size="8" fill="#047857" font-weight="700" text-anchor="middle">115</text>
          <text x="265" y="14" font-size="8" fill="#047857" font-weight="700" text-anchor="middle">122</text>

          
          <line x1="30" y1="20" x2="30" y2="110" stroke="#10b981" stroke-width="1.5" />
          <line x1="95" y1="20" x2="95" y2="110" stroke="#10b981" stroke-width="1.5" />
          <line x1="192" y1="20" x2="192" y2="110" stroke="#10b981" stroke-width="1.5" />
          <line x1="265" y1="20" x2="265" y2="110" stroke="#10b981" stroke-width="1.5" />

          
          <text x="30" y="30" font-size="9" fill="#10b981" font-weight="700" text-anchor="middle">1.1</text>
          <text x="95" y="30" font-size="9" fill="#10b981" font-weight="700" text-anchor="middle">1.2</text>
          <text x="192" y="30" font-size="9" fill="#10b981" font-weight="700" text-anchor="middle">1.3</text>
          <text x="265" y="30" font-size="9" fill="#10b981" font-weight="700" text-anchor="middle">1.4</text>

          
          <line x1="0" y1="70" x2="300" y2="70" stroke="#cbd5e1" stroke-width="1" />

          
          <path d="M 15 70 Q 25 70 28 42 L 30 35 L 32 42 Q 35 70 50 70" fill="#3b82f6" />
          <path d="M 75 70 Q 90 70 93 45 L 95 38 L 97 45 Q 102 70 120 70" fill="#3b82f6" />
          <path d="M 172 70 Q 187 70 190 40 L 192 34 L 194 40 Q 200 70 217 70" fill="#3b82f6" />
          <path d="M 245 70 Q 260 70 263 44 L 265 37 L 267 44 Q 272 70 290 70" fill="#3b82f6" />

          
          <line id="playheadMap" x1="0" y1="0" x2="0" y2="110" stroke="#10b981" stroke-width="2" opacity="0" />
        </svg>
      </div>
      <div class="status-text">
        <span style="color:#10b981;">●</span> Grid flexes • Preserves live groove
      </div>
    </div>
  </div>

  <script>
    let audioCtx = null;
    let animInterval = null;

    function initAudio() {
      if (!audioCtx) {
        audioCtx = new (window.AudioContext || window.webkitAudioContext)();
      }
      if (audioCtx.state === 'suspended') {
        audioCtx.resume();
      }
    }

    function playTone(freq, time, type = 'sine', dur = 0.08) {
      if (!audioCtx) return;
      const osc = audioCtx.createOscillator();
      const gain = audioCtx.createGain();
      osc.type = type;
      osc.frequency.setValueAtTime(freq, time);
      gain.gain.setValueAtTime(0.3, time);
      gain.gain.exponentialRampToValueAtTime(0.001, time + dur);
      osc.connect(gain);
      gain.connect(audioCtx.destination);
      osc.start(time);
      osc.stop(time + dur);
    }

    function resetPlayheads() {
      clearInterval(animInterval);
      document.getElementById('playheadWarp').setAttribute('opacity', '0');
      document.getElementById('playheadMap').setAttribute('opacity', '0');
      document.getElementById('btnPlayWarp').classList.remove('active');
      document.getElementById('btnPlayMap').classList.remove('active');
    }

    function animateLine(lineId, durationMs) {
      const line = document.getElementById(lineId);
      line.setAttribute('opacity', '1');
      const start = Date.now();
      clearInterval(animInterval);
      animInterval = setInterval(() => {
        const elapsed = Date.now() - start;
        const prog = Math.min(elapsed / durationMs, 1);
        line.setAttribute('x1', prog * 300);
        line.setAttribute('x2', prog * 300);
        if (prog >= 1) {
          resetPlayheads();
        }
      }, 16);
    }

    function playWarpDemo() {
      initAudio();
      resetPlayheads();
      document.getElementById('btnPlayWarp').classList.add('active');

      const now = audioCtx.currentTime + 0.05;
      const beatDur = 0.45; // 133 BPM steady
      const totalDur = beatDur * 4;

      // 4 steady clicks
      playTone(800, now, 'triangle');
      playTone(500, now + beatDur, 'triangle');
      playTone(500, now + beatDur * 2, 'triangle');
      playTone(500, now + beatDur * 3, 'triangle');

      animateLine('playheadWarp', totalDur * 1000);
    }

    function playMapDemo() {
      initAudio();
      resetPlayheads();
      document.getElementById('btnPlayMap').classList.add('active');

      const now = audioCtx.currentTime + 0.05;
      // Expressive dynamic intervals matching the SVG transient positions: 30, 95, 192, 265 (out of 300)
      const totalDur = 1.8;
      const t1 = now + (30 / 300) * totalDur;
      const t2 = now + (95 / 300) * totalDur;  // rushed
      const t3 = now + (192 / 300) * totalDur; // pushed back
      const t4 = now + (265 / 300) * totalDur;

      playTone(800, t1, 'sine', 0.1);
      playTone(500, t2, 'sine', 0.1);
      playTone(500, t3, 'sine', 0.1);
      playTone(500, t4, 'sine', 0.1);

      animateLine('playheadMap', totalDur * 1000);
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      user-select: none;
    }

    .byte-wrapper {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    /* Bit Grid Display */
    .nibbles-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
    }

    .nibble-box {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      box-shadow: 0 2px 6px rgba(0, 0, 0, 0.03);
    }

    .nibble-header {
      font-size: 13px;
      font-weight: 700;
      letter-spacing: 0.2px;
    }
    .type-color { color: #2563eb; }
    .chan-color { color: #0d9488; }

    .bit-strip {
      display: flex;
      gap: 4px;
      width: 100%;
      justify-content: center;
    }

    .bit-cell {
      flex: 1;
      max-width: 38px;
      height: 38px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-family: ui-monospace, monospace;
      font-size: 18px;
      font-weight: 700;
      border-radius: 6px;
      border: 1px solid #cbd5e1;
      background: #f1f5f9;
      color: #1e2945;
      transition: all 0.2s ease;
    }

    .bit-cell.type-bit {
      background: #eff6ff;
      border-color: #93c5fd;
      color: #1d4ed8;
    }

    .bit-cell.chan-bit {
      background: #f0fdfa;
      border-color: #99f6e4;
      color: #0f766e;
    }

    /* Interactive Panels */
    .controls-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      max-width: 580px;
    }

    .panel {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px;
      display: flex;
      flex-direction: column;
      gap: 5px;
    }

    .tag-btn {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 6px 10px;
      border-radius: 6px;
      border: 1px solid #e2e8f0;
      background: #f8fafc;
      cursor: pointer;
      font-size: 12.5px;
      font-weight: 600;
      color: #334155;
      transition: background 0.15s ease, border-color 0.15s ease;
    }

    .tag-btn:hover {
      background: #eff6ff;
      border-color: #bfdbfe;
    }

    .tag-btn.active {
      background: #2563eb;
      border-color: #2563eb;
      color: #ffffff;
      box-shadow: 0 2px 4px rgba(37, 99, 235, 0.2);
    }

    .tag-btn .hex-code {
      font-family: ui-monospace, monospace;
      font-size: 11.5px;
      opacity: 0.85;
    }

    /* Channel Slider & Stepper */
    .chan-control {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 8px;
      height: 100%;
      padding: 4px;
    }

    .chan-display {
      font-size: 20px;
      font-weight: 800;
      color: #0f766e;
      display: flex;
      align-items: baseline;
      gap: 4px;
    }

    .chan-display span {
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
    }

    .chan-slider {
      width: 100%;
      accent-color: #0d9488;
      cursor: pointer;
    }

    .chan-steps {
      display: flex;
      justify-content: space-between;
      width: 100%;
      font-size: 10.5px;
      font-weight: 600;
      color: #94a3b8;
      font-family: ui-monospace, monospace;
    }

    /* Formula Banner */
    .formula-bar {
      width: 100%;
      max-width: 580px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 10px;
      padding: 8px 12px;
      display: flex;
      align-items: center;
      justify-content: space-around;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.02);
      font-size: 13px;
    }

    .formula-item {
      display: flex;
      align-items: center;
      gap: 6px;
      font-weight: 600;
    }

    .calc-tag {
      padding: 2px 8px;
      border-radius: 5px;
      font-family: ui-monospace, monospace;
      font-size: 12px;
      font-weight: 700;
      background: #f1f5f9;
      color: #334155;
    }

    .hex-out {
      background: #fef3c7;
      color: #92400e;
      border: 1px solid #fde68a;
    }
  </style>
</head>
<body>

  
  <div class="byte-wrapper">
    <div class="nibbles-row">
      
      <div class="nibble-box">
        <span class="nibble-header type-color">Message Type (1sss)</span>
        <div class="bit-strip" id="typeBits">
          <div class="bit-cell type-bit">1</div>
          <div class="bit-cell type-bit">0</div>
          <div class="bit-cell type-bit">0</div>
          <div class="bit-cell type-bit">1</div>
        </div>
      </div>

      
      <div class="nibble-box">
        <span class="nibble-header chan-color">Channel (nnnn)</span>
        <div class="bit-strip" id="chanBits">
          <div class="bit-cell chan-bit">0</div>
          <div class="bit-cell chan-bit">0</div>
          <div class="bit-cell chan-bit">0</div>
          <div class="bit-cell chan-bit">0</div>
        </div>
      </div>
    </div>
  </div>

  
  <div class="controls-grid">
    
    <div class="panel">
      <button class="tag-btn" data-bits="1000" data-hex="8">
        <span>Note-Off</span>
        <span class="hex-code">1000 (8x)</span>
      </button>
      <button class="tag-btn active" data-bits="1001" data-hex="9">
        <span>Note-On</span>
        <span class="hex-code">1001 (9x)</span>
      </button>
      <button class="tag-btn" data-bits="1100" data-hex="C">
        <span>Program Change</span>
        <span class="hex-code">1100 (Cx)</span>
      </button>
      <button class="tag-btn" data-bits="1110" data-hex="E">
        <span>Pitch Bend</span>
        <span class="hex-code">1110 (Ex)</span>
      </button>
    </div>

    
    <div class="panel">
      <div class="chan-control">
        <div class="chan-display">
          <span>Channel</span> <span id="chanNum">1</span>
        </div>
        <input type="range" class="chan-slider" id="chanSlider" min="0" max="15" value="0">
        <div class="chan-steps">
          <span>0000 (1)</span>
          <span>1111 (16)</span>
        </div>
      </div>
    </div>
  </div>

  
  <div class="formula-bar">
    <div class="formula-item">
      <span>Formula:</span>
      <span class="calc-tag" id="formulaText">0000₂ (0) + 1 = Ch 1</span>
    </div>
    <div class="formula-item">
      <span>Status:</span>
      <span class="calc-tag hex-out" id="statusHex">0x90</span>
    </div>
  </div>

  <script>
    let currentTypeBits = '1001';
    let currentTypeHex = '9';
    let currentChanVal = 0;

    const typeBitEls = document.querySelectorAll('#typeBits .bit-cell');
    const chanBitEls = document.querySelectorAll('#chanBits .bit-cell');
    const typeButtons = document.querySelectorAll('.tag-btn');
    const chanSlider = document.getElementById('chanSlider');
    const chanNum = document.getElementById('chanNum');
    const formulaText = document.getElementById('formulaText');
    const statusHex = document.getElementById('statusHex');

    function updateView() {
      // Update Type bits display
      for (let i = 0; i < 4; i++) {
        typeBitEls[i].textContent = currentTypeBits[i];
      }

      // Update Channel bits display
      const binStr = currentChanVal.toString(2).padStart(4, '0');
      for (let i = 0; i < 4; i++) {
        chanBitEls[i].textContent = binStr[i];
      }

      // Channel Number calculation: Value + 1
      const chNumber = currentChanVal + 1;
      chanNum.textContent = chNumber;
      formulaText.textContent = `${binStr}₂ (${currentChanVal}) + 1 = Ch ${chNumber}`;

      // Status Byte Hex code: TypeNibble + ChanNibble
      const hexChan = currentChanVal.toString(16).toUpperCase();
      statusHex.textContent = `0x${currentTypeHex}${hexChan}`;
    }

    typeButtons.forEach(btn => {
      btn.addEventListener('click', () => {
        typeButtons.forEach(b => b.classList.remove('active'));
        btn.classList.add('active');
        currentTypeBits = btn.dataset.bits;
        currentTypeHex = btn.dataset.hex;
        updateView();
      });
    });

    chanSlider.addEventListener('input', (e) => {
      currentChanVal = parseInt(e.target.value, 10);
      updateView();
    });

    updateView();
  </script>
</body>
</html>

The MIDI 1.0 Protocol: Channel Voice Messages and Status Bytes

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      user-select: none;
    }

    .tabs {
      display: flex;
      gap: 6px;
      background: #f1f5f9;
      padding: 4px;
      border-radius: 8px;
    }
    .tab {
      flex: 1;
      text-align: center;
      padding: 6px 8px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 6px;
      border: none;
      background: transparent;
      color: #64748b;
      cursor: pointer;
      transition: all 0.2s ease;
    }
    .tab.active {
      background: #ffffff;
      color: #0284c7;
      box-shadow: 0 1px 3px rgba(0,0,0,0.08);
    }

    .view-panel {
      display: none;
      flex-direction: column;
      gap: 12px;
    }
    .view-panel.active {
      display: flex;
    }

    .bytes-container {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 8px;
    }

    @media (max-width: 480px) {
      .bytes-container {
        grid-template-columns: 1fr;
      }
    }

    .byte-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 6px;
      position: relative;
    }
    .byte-card.status { border-top: 4px solid #0284c7; }
    .byte-card.data1 { border-top: 4px solid #10b981; }
    .byte-card.data2 { border-top: 4px solid #f59e0b; }

    .byte-header {
      font-size: 11px;
      font-weight: 700;
      letter-spacing: 0.5px;
      color: #64748b;
      display: flex;
      justify-content: space-between;
    }

    .bit-display {
      font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
      font-size: 15px;
      font-weight: 700;
      letter-spacing: 1px;
      background: #f8fafc;
      padding: 6px;
      border-radius: 6px;
      text-align: center;
      border: 1px solid #edf2f7;
    }
    .status-bit { color: #0284c7; }
    .channel-bit { color: #6366f1; }
    .data-msb { color: #94a3b8; }
    .data-val { color: #1e2945; }

    .values-row {
      display: flex;
      justify-content: space-around;
      background: #f8fafc;
      border-radius: 6px;
      padding: 4px;
      font-size: 12px;
      font-weight: 600;
    }
    .val-badge {
      display: flex;
      flex-direction: column;
      align-items: center;
    }
    .val-label { font-size: 9px; color: #94a3b8; }

    .desc-box {
      font-size: 13px;
      font-weight: 600;
      text-align: center;
      padding: 6px 4px;
      border-radius: 6px;
      background: #f1f5f9;
      color: #334155;
    }
    .byte-card.status .desc-box { background: #e0f2fe; color: #0369a1; }
    .byte-card.data1 .desc-box { background: #dcfce7; color: #15803d; }
    .byte-card.data2 .desc-box { background: #fef3c7; color: #b45309; }

    .compare-box {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 10px 12px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    .compare-row {
      display: grid;
      grid-template-columns: 85px 1fr auto;
      align-items: center;
      gap: 8px;
      font-size: 12px;
    }
    @media (max-width: 400px) {
      .compare-row { grid-template-columns: 70px 1fr auto; }
    }

    .code-chip {
      font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
      font-weight: 700;
      padding: 4px 6px;
      border-radius: 4px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      font-size: 12px;
      text-align: center;
    }

    .action-badge {
      font-weight: 700;
      padding: 3px 8px;
      border-radius: 4px;
      font-size: 11px;
      text-align: center;
    }
    .badge-off { background: #fee2e2; color: #b91c1c; }
    .badge-eq { background: #f3e8ff; color: #7e22ce; font-weight: 800; }

    .interactive-bar {
      display: flex;
      justify-content: space-between;
      align-items: center;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 12px;
    }

    .sound-btn {
      background: #0284c7;
      color: #ffffff;
      border: none;
      border-radius: 6px;
      padding: 6px 14px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: background 0.15s;
    }
    .sound-btn:hover { background: #0369a1; }
    .sound-btn:active { background: #075985; }

    .shortcut-pill {
      font-size: 11px;
      font-weight: 700;
      color: #6366f1;
      background: #eef2ff;
      padding: 3px 8px;
      border-radius: 12px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }
  </style>
</head>
<body>

  <div class="tabs">
    <button class="tab active" id="tabDissect">Note-On Dissection</button>
    <button class="tab" id="tabCompare">Note-Off vs Shortcut</button>
  </div>

  
  <div class="view-panel active" id="panelDissect">
    <div class="bytes-container">
      
      <div class="byte-card status">
        <div class="byte-header">
          <span>BYTE 1</span>
          <span>STATUS</span>
        </div>
        <div class="bit-display">
          <span class="status-bit">1001</span> <span class="channel-bit">0000</span>
        </div>
        <div class="values-row">
          <div class="val-badge"><span class="val-label">HEX</span><span>90</span></div>
          <div class="val-badge"><span class="val-label">DEC</span><span>144</span></div>
        </div>
        <div class="desc-box">
          Note-On, Ch 1
        </div>
      </div>

      
      <div class="byte-card data1">
        <div class="byte-header">
          <span>BYTE 2</span>
          <span>DATA 1</span>
        </div>
        <div class="bit-display">
          <span class="data-msb">0</span><span class="data-val">011 1100</span>
        </div>
        <div class="values-row">
          <div class="val-badge"><span class="val-label">HEX</span><span>3C</span></div>
          <div class="val-badge"><span class="val-label">DEC</span><span>60</span></div>
        </div>
        <div class="desc-box">
          Middle C (C4)
        </div>
      </div>

      
      <div class="byte-card data2">
        <div class="byte-header">
          <span>BYTE 3</span>
          <span>DATA 2</span>
        </div>
        <div class="bit-display">
          <span class="data-msb">0</span><span class="data-val">110 0100</span>
        </div>
        <div class="values-row">
          <div class="val-badge"><span class="val-label">HEX</span><span>64</span></div>
          <div class="val-badge"><span class="val-label">DEC</span><span>100</span></div>
        </div>
        <div class="desc-box">
          Velocity: 100/127
        </div>
      </div>
    </div>
  </div>

  
  <div class="view-panel" id="panelCompare">
    <div class="compare-box">
      <div class="compare-row">
        <span style="font-weight:700; color:#64748b;">Standard</span>
        <div class="code-chip">80 3C 00</div>
        <div class="action-badge badge-off">Note-Off</div>
      </div>

      <div class="compare-row">
        <div class="shortcut-pill">✦ Shortcut</div>
        <div class="code-chip" style="border-color:#6366f1;">90 3C 00</div>
        <div class="action-badge badge-eq">≡ Note-Off</div>
      </div>
    </div>

    <div class="compare-box" style="font-size:12px; background:#f8fafc; border:1px dashed #cbd5e1; gap:4px;">
      <div style="font-weight:700; color:#334155;">Running Status Rule</div>
      <div style="color:#64748b; font-family:ui-monospace, monospace; font-size:11px;">
        90 3C 64 &nbsp;→&nbsp; [Key Press: C4 on]<br>
        &nbsp;&nbsp; 3C 00 &nbsp;→&nbsp; [Key Release: C4 off]
      </div>
    </div>
  </div>

  
  <div class="interactive-bar">
    <span style="font-size:12px; font-weight:600; color:#475569;">Audition C4 (60):</span>
    <button class="sound-btn" id="playBtn">
      <span>▶ Play Note</span>
    </button>
  </div>

  <script>
    const tabDissect = document.getElementById('tabDissect');
    const tabCompare = document.getElementById('tabCompare');
    const panelDissect = document.getElementById('panelDissect');
    const panelCompare = document.getElementById('panelCompare');
    const playBtn = document.getElementById('playBtn');

    tabDissect.addEventListener('click', () => {
      tabDissect.classList.add('active');
      tabCompare.classList.remove('active');
      panelDissect.classList.add('active');
      panelCompare.classList.remove('active');
    });

    tabCompare.addEventListener('click', () => {
      tabCompare.classList.add('active');
      tabDissect.classList.remove('active');
      panelCompare.classList.add('active');
      panelDissect.classList.remove('active');
    });

    // Web Audio synthesizer for Middle C (261.63 Hz)
    let audioCtx = null;
    playBtn.addEventListener('click', () => {
      if (!audioCtx) {
        audioCtx = new (window.AudioContext || window.webkitAudioContext)();
      }
      if (audioCtx.state === 'suspended') {
        audioCtx.resume();
      }

      const osc = audioCtx.createOscillator();
      const gain = audioCtx.createGain();
      
      osc.type = 'triangle';
      osc.frequency.setValueAtTime(261.63, audioCtx.currentTime); // Middle C (C4 / Dec 60)

      // Velocity ~100/127 gain shaping
      const now = audioCtx.currentTime;
      gain.gain.setValueAtTime(0.001, now);
      gain.gain.linearRampToValueAtTime(0.28, now + 0.02);
      gain.gain.exponentialRampToValueAtTime(0.001, now + 0.6);

      osc.connect(gain);
      gain.connect(audioCtx.destination);

      osc.start(now);
      osc.stop(now + 0.62);
    });
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, sans-serif; }
    body { background: #ffffff; color: #1e2945; padding: 12px; display: flex; flex-direction: column; gap: 12px; }
    
    .section-title {
      font-size: 13px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #64748b;
      margin-bottom: 6px;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    
    .badge-count {
      font-size: 11px;
      background: #f1f5f9;
      color: #475569;
      padding: 2px 6px;
      border-radius: 4px;
      font-weight: 600;
    }

    .msg-card {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    .byte-row {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      align-items: center;
    }

    .byte-box {
      flex: 1;
      min-width: 130px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 8px;
      padding: 6px 8px;
      display: flex;
      flex-direction: column;
      gap: 2px;
    }

    .byte-tag {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
    }

    .status-tag { color: #6366f1; }
    .data-tag { color: #0284c7; }
    .msb-tag { color: #0d9488; }
    .lsb-tag { color: #d97706; }

    .bin-val {
      font-family: ui-monospace, monospace;
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
      letter-spacing: 1px;
    }

    .hex-val {
      font-size: 11px;
      color: #64748b;
    }

    .result-pill {
      background: #f0fdf4;
      border: 1px solid #bbf7d0;
      color: #15803d;
      padding: 6px 10px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      display: flex;
      align-items: center;
      gap: 6px;
      white-space: nowrap;
    }

    .math-bar {
      background: #f1f5f9;
      border-radius: 6px;
      padding: 6px 10px;
      font-family: ui-monospace, monospace;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 6px;
    }

    .math-val {
      color: #2563eb;
      font-weight: 700;
    }

    .controls-row {
      display: flex;
      align-items: center;
      gap: 10px;
      flex-wrap: wrap;
    }

    input[type=range] {
      flex: 1;
      min-width: 140px;
      accent-color: #2563eb;
      cursor: pointer;
    }

    .preset-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 4px 8px;
      font-size: 11px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
    }

    .preset-btn:hover {
      background: #f8fafc;
      border-color: #94a3b8;
    }

    .pitch-track {
      position: relative;
      height: 12px;
      background: #e2e8f0;
      border-radius: 6px;
      margin: 4px 0 2px;
      overflow: hidden;
    }

    .pitch-center-line {
      position: absolute;
      left: 50%;
      top: 0;
      bottom: 0;
      width: 2px;
      background: #94a3b8;
      transform: translateX(-50%);
    }

    .pitch-indicator {
      position: absolute;
      top: 2px;
      bottom: 2px;
      width: 8px;
      background: #2563eb;
      border-radius: 4px;
      transform: translateX(-50%);
      transition: left 0.05s ease;
    }
  </style>
</head>
<body>

  
  <div class="msg-card">
    <div class="section-title">
      <span>Program Change</span>
      <span class="badge-count">2 Bytes</span>
    </div>
    <div class="byte-row">
      <div class="byte-box">
        <span class="byte-tag status-tag">Status Byte</span>
        <span class="bin-val">1100 0001</span>
        <span class="hex-val">0xC1 → Ch 2</span>
      </div>
      <div class="byte-box">
        <span class="byte-tag data-tag">Data (Patch #)</span>
        <span class="bin-val">0000 0101</span>
        <span class="hex-val">0x05 → Index 5</span>
      </div>
      <div class="result-pill">
        <span>🎹 Electric Piano</span>
      </div>
    </div>
  </div>

  
  <div class="msg-card">
    <div class="section-title">
      <span>Pitch Bend (14-bit)</span>
      <span class="badge-count">3 Bytes</span>
    </div>

    <div class="byte-row">
      <div class="byte-box">
        <span class="byte-tag status-tag">Status Byte</span>
        <span class="bin-val">1110 0000</span>
        <span class="hex-val">0xE0 → Ch 1</span>
      </div>
      <div class="byte-box">
        <span class="byte-tag lsb-tag">LSB (7-bit)</span>
        <span class="bin-val" id="lsbBin">0000000</span>
        <span class="hex-val" id="lsbHex">0x00 • Val: 0</span>
      </div>
      <div class="byte-box">
        <span class="byte-tag msb-tag">MSB (7-bit)</span>
        <span class="bin-val" id="msbBin">1000000</span>
        <span class="hex-val" id="msbHex">0x40 • Val: 64</span>
      </div>
    </div>

    
    <div class="math-bar">
      <span>(<span id="msbMath" class="math-val">64</span> × 128) + <span id="lsbMath" class="math-val">0</span></span>
      <span>= <strong id="totalVal" class="math-val">8,192</strong> <span id="centerTag" style="color:#15803d; font-size:11px;">(Center / No Bend)</span></span>
    </div>

    
    <div class="pitch-track">
      <div class="pitch-center-line"></div>
      <div class="pitch-indicator" id="pitchInd" style="left: 50%;"></div>
    </div>

    <div class="controls-row">
      <input type="range" id="pitchSlider" min="0" max="16383" value="8192">
      <button class="preset-btn" onclick="setPitch(0)">Min (0)</button>
      <button class="preset-btn" onclick="setPitch(8192)">Center (8192)</button>
      <button class="preset-btn" onclick="setPitch(16383)">Max (16383)</button>
    </div>
  </div>

  <script>
    const slider = document.getElementById('pitchSlider');
    const lsbBin = document.getElementById('lsbBin');
    const lsbHex = document.getElementById('lsbHex');
    const msbBin = document.getElementById('msbBin');
    const msbHex = document.getElementById('msbHex');
    const lsbMath = document.getElementById('lsbMath');
    const msbMath = document.getElementById('msbMath');
    const totalVal = document.getElementById('totalVal');
    const centerTag = document.getElementById('centerTag');
    const pitchInd = document.getElementById('pitchInd');

    function update(val) {
      val = parseInt(val, 10);
      const lsb = val & 0x7F;
      const msb = (val >> 7) & 0x7F;

      lsbBin.textContent = lsb.toString(2).padStart(7, '0');
      lsbHex.textContent = '0x' + lsb.toString(16).toUpperCase().padStart(2, '0') + ' • Val: ' + lsb;

      msbBin.textContent = msb.toString(2).padStart(7, '0');
      msbHex.textContent = '0x' + msb.toString(16).toUpperCase().padStart(2, '0') + ' • Val: ' + msb;

      lsbMath.textContent = lsb;
      msbMath.textContent = msb;
      totalVal.textContent = val.toLocaleString();

      if (val === 8192) {
        centerTag.textContent = '(Center / No Bend)';
        centerTag.style.color = '#15803d';
      } else if (val < 8192) {
        centerTag.textContent = '(Bend Down)';
        centerTag.style.color = '#d97706';
      } else {
        centerTag.textContent = '(Bend Up)';
        centerTag.style.color = '#2563eb';
      }

      const percent = (val / 16383) * 100;
      pitchInd.style.left = percent + '%';
    }

    function setPitch(v) {
      slider.value = v;
      update(v);
    }

    slider.addEventListener('input', (e) => update(e.target.value));
    update(8192);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, sans-serif; }
    body { background: #f8fafc; color: #1e293b; padding: 12px; }

    .nav { display: flex; gap: 6px; margin-bottom: 12px; }
    .tab {
      flex: 1; padding: 8px 4px; font-size: 13px; font-weight: 600;
      background: #fff; border: 1px solid #cbd5e1; border-radius: 6px;
      cursor: pointer; text-align: center; color: #64748b;
      box-shadow: 0 1px 2px rgba(0,0,0,0.04);
      transition: all 0.2s ease;
    }
    .tab.active {
      background: #2563eb; color: #fff; border-color: #2563eb;
      box-shadow: 0 2px 4px rgba(37,99,235,0.25);
    }

    .raw-bytes {
      display: flex; justify-content: center; gap: 8px; margin-bottom: 12px;
      font-family: ui-monospace, monospace; font-size: 18px; font-weight: 700;
    }
    .byte-tag {
      padding: 6px 12px; border-radius: 6px; border: 1px solid transparent;
      display: flex; flex-direction: column; align-items: center;
    }
    .byte-lbl { font-size: 10px; font-weight: 600; text-transform: uppercase; margin-top: 2px; }

    .c-op { background: #ede9fe; color: #6d28d9; border-color: #ddd6fe; }
    .c-ch { background: #e0f2fe; color: #0369a1; border-color: #bae6fd; }
    .c-d1 { background: #dcfce7; color: #15803d; border-color: #bbf7d0; }
    .c-d2 { background: #fef3c7; color: #b45309; border-color: #fde68a; }

    .decode-grid {
      display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
      gap: 8px; margin-bottom: 12px;
    }
    .decode-card {
      background: #fff; border-radius: 8px; padding: 10px;
      border: 1px solid #e2e8f0; border-top: 3px solid #cbd5e1;
    }
    .decode-card.op { border-top-color: #7c3aed; }
    .decode-card.ch { border-top-color: #0284c7; }
    .decode-card.d1 { border-top-color: #16a34a; }
    .decode-card.d2 { border-top-color: #d97706; }

    .card-title { font-size: 11px; font-weight: 700; color: #64748b; margin-bottom: 4px; }
    .card-val { font-size: 15px; font-weight: 700; color: #0f172a; margin-bottom: 2px; }
    .card-sub { font-size: 11px; color: #64748b; font-family: ui-monospace, monospace; }

    .visual-panel {
      background: #fff; border: 1px solid #e2e8f0; border-radius: 8px;
      padding: 12px; display: flex; align-items: center; justify-content: space-between;
      min-height: 84px;
    }
    .vis-col { display: flex; flex-direction: column; gap: 4px; }
    .meter-bar { width: 120px; height: 10px; background: #e2e8f0; border-radius: 5px; overflow: hidden; }
    .meter-fill { height: 100%; border-radius: 5px; transition: width 0.3s ease; }

    .audio-btn {
      padding: 8px 14px; background: #0f172a; color: #fff; border: none;
      border-radius: 6px; font-size: 13px; font-weight: 600; cursor: pointer;
      display: inline-flex; align-items: center; gap: 6px;
    }
    .audio-btn:active { background: #334155; }

    .bipolar-track {
      width: 140px; height: 12px; background: #e2e8f0; border-radius: 6px;
      position: relative;
    }
    .bipolar-center {
      position: absolute; left: 50%; top: -3px; bottom: -3px; width: 2px;
      background: #64748b;
    }
    .bipolar-fill {
      position: absolute; top: 0; bottom: 0; left: 50%; width: 25%;
      background: #d97706; border-radius: 0 4px 4px 0;
    }
  </style>
</head>
<body>

  <div class="nav">
    <button class="tab active" onclick="setEx(0)">1: Note-On</button>
    <button class="tab" onclick="setEx(1)">2: Program</button>
    <button class="tab" onclick="setEx(2)">3: Pitch Bend</button>
  </div>

  <div class="raw-bytes" id="rawBytes"></div>
  <div class="decode-grid" id="decodeGrid"></div>
  <div class="visual-panel" id="visualPanel"></div>

  <script>
    const examples = [
      {
        bytes: [
          { val: '9', cls: 'c-op', lbl: 'Opcode' },
          { val: '2', cls: 'c-ch', lbl: 'Channel' },
          { val: '40', cls: 'c-d1', lbl: 'Data 1' },
          { val: '7F', cls: 'c-d2', lbl: 'Data 2' }
        ],
        cards: [
          { type: 'op', title: 'STATUS (NIBBLE 1)', val: 'Note-On', sub: "9₁₆ = 1001₂" },
          { type: 'ch', title: 'CHANNEL (NIBBLE 2)', val: 'Channel 3', sub: "2₁₆ (0010₂) + 1" },
          { type: 'd1', title: 'NOTE NUMBER (DATA 1)', val: 'E3 (Pitch)', sub: "40₁₆ = 64₁₀" },
          { type: 'd2', title: 'VELOCITY (DATA 2)', val: '127 (Max)', sub: "7F₁₆ = 127₁₀ (100%)" }
        ],
        renderVis: () => `
          <div class="vis-col">
            <span style="font-size:12px;font-weight:600;color:#64748b;">Strike Velocity</span>
            <div class="meter-bar"><div class="meter-fill" style="width:100%;background:#16a34a;"></div></div>
            <span style="font-size:11px;color:#16a34a;font-weight:600;">127 / 127 (100%)</span>
          </div>
          <button class="audio-btn" onclick="playTone(329.63, 0.5)">
            <span>▶ Play E3</span>
            <span style="font-size:11px;opacity:0.8;">(329.6 Hz)</span>
          </button>
        `
      },
      {
        bytes: [
          { val: 'C', cls: 'c-op', lbl: 'Opcode' },
          { val: '2', cls: 'c-ch', lbl: 'Channel' },
          { val: '0A', cls: 'c-d1', lbl: 'Data 1' }
        ],
        cards: [
          { type: 'op', title: 'STATUS (NIBBLE 1)', val: 'Program Change', sub: "C₁₆ = 1100₂" },
          { type: 'ch', title: 'CHANNEL (NIBBLE 2)', val: 'Channel 3', sub: "2₁₆ (0010₂) + 1" },
          { type: 'd1', title: 'PROGRAM ID (DATA 1)', val: 'Patch #10', sub: "0A₁₆ = 10₁₀ (Glockenspiel)" }
        ],
        renderVis: () => `
          <div class="vis-col">
            <span style="font-size:12px;font-weight:600;color:#64748b;">Instrument Preset</span>
            <span style="font-size:14px;font-weight:700;color:#0f172a;">#10 Glockenspiel</span>
          </div>
          <button class="audio-btn" onclick="playTone(1046.5, 0.4)">
            <span>▶ Glockenspiel</span>
            <span style="font-size:11px;opacity:0.8;">(C6)</span>
          </button>
        `
      },
      {
        bytes: [
          { val: 'E', cls: 'c-op', lbl: 'Opcode' },
          { val: '2', cls: 'c-ch', lbl: 'Channel' },
          { val: '00', cls: 'c-d1', lbl: 'LSB' },
          { val: '60', cls: 'c-d2', lbl: 'MSB' }
        ],
        cards: [
          { type: 'op', title: 'STATUS (NIBBLE 1)', val: 'Pitch Bend', sub: "E₁₆ = 1110₂" },
          { type: 'ch', title: 'CHANNEL (NIBBLE 2)', val: 'Channel 3', sub: "2₁₆ (0010₂) + 1" },
          { type: 'd1', title: '14-BIT VALUE', val: '12,288 (+50%)', sub: "(96 × 128) + 0" },
          { type: 'd2', title: 'OFFSET FROM CENTER', val: '+4,096 Up', sub: "Center = 8,192" }
        ],
        renderVis: () => `
          <div class="vis-col">
            <span style="font-size:12px;font-weight:600;color:#64748b;">Pitch Wheel Position</span>
            <div class="bipolar-track">
              <div class="bipolar-center"></div>
              <div class="bipolar-fill" style="width:25%;"></div>
            </div>
            <span style="font-size:11px;color:#d97706;font-weight:600;">+1 Semitone Up (12,288)</span>
          </div>
          <button class="audio-btn" onclick="playBendTone(329.63, 349.23)">
            <span>▶ Play Bend</span>
            <span style="font-size:11px;opacity:0.8;">(E3 → F3)</span>
          </button>
        `
      }
    ];

    function setEx(idx) {
      document.querySelectorAll('.tab').forEach((t, i) => {
        t.classList.toggle('active', i === idx);
      });

      const data = examples[idx];
      document.getElementById('rawBytes').innerHTML = data.bytes.map(b => `
        <div class="byte-tag ${b.cls}">
          <span>${b.val}</span>
          <span class="byte-lbl">${b.lbl}</span>
        </div>
      `).join('');

      document.getElementById('decodeGrid').innerHTML = data.cards.map(c => `
        <div class="decode-card ${c.type}">
          <div class="card-title">${c.title}</div>
          <div class="card-val">${c.val}</div>
          <div class="card-sub">${c.sub}</div>
        </div>
      `).join('');

      document.getElementById('visualPanel').innerHTML = data.renderVis();
    }

    function playTone(freq, dur = 0.4) {
      try {
        const ctx = new (window.AudioContext || window.webkitAudioContext)();
        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(freq, ctx.currentTime);
        gain.gain.setValueAtTime(0.3, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    function playBendTone(f1, f2) {
      try {
        const ctx = new (window.AudioContext || window.webkitAudioContext)();
        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(f1, ctx.currentTime);
        osc.frequency.linearRampToValueAtTime(f2, ctx.currentTime + 0.35);
        gain.gain.setValueAtTime(0.2, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.6);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.6);
      } catch (e) {}
    }

    setEx(0);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>MIDI Byte Classification</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      background: transparent;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
    }

    .main-wrap {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 16px;
    }

    /* Byte Register */
    .register-container {
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
    }

    .register-header {
      width: 100%;
      display: flex;
      justify-content: space-between;
      font-size: 13px;
      font-weight: 700;
      color: #64748b;
      padding: 0 4px;
    }

    .msb-label {
      color: #0284c7;
    }

    .lsb-label {
      color: #64748b;
    }

    .byte-grid {
      display: grid;
      grid-template-columns: 1.25fr repeat(7, 1fr);
      width: 100%;
      gap: 4px;
      background: #f1f5f9;
      padding: 6px;
      border-radius: 12px;
      border: 1px solid #e2e8f0;
    }

    .bit-box {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 8px 2px;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      transition: all 0.25s ease;
      cursor: default;
      user-select: none;
    }

    .bit-box.msb {
      cursor: pointer;
      background: #e0f2fe;
      border: 2px solid #22b7ff;
      box-shadow: 0 2px 6px rgba(34, 183, 255, 0.2);
    }

    .bit-box.msb.is-zero {
      background: #fff7ed;
      border-color: #ff9f43;
      box-shadow: 0 2px 6px rgba(255, 159, 67, 0.2);
    }

    .bit-name {
      font-size: 11px;
      font-weight: 600;
      color: #94a3b8;
      margin-bottom: 2px;
    }

    .bit-box.msb .bit-name {
      color: #0284c7;
      font-weight: 800;
    }

    .bit-box.msb.is-zero .bit-name {
      color: #d97706;
    }

    .bit-val {
      font-size: 18px;
      font-weight: 800;
      font-family: ui-monospace, "Cascadia Code", monospace;
      color: #1e2945;
    }

    .bit-box.msb .bit-val {
      color: #0369a1;
      font-size: 20px;
    }

    .bit-box.msb.is-zero .bit-val {
      color: #b45309;
    }

    /* Branch Indicators */
    .branch-tree {
      width: 100%;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
    }

    .card-branch {
      position: relative;
      display: flex;
      flex-direction: column;
      border-radius: 12px;
      padding: 14px;
      border: 2px solid transparent;
      background: #f8f9fa;
      transition: all 0.25s ease;
      cursor: pointer;
    }

    /* Status Byte Card (Blue) */
    .card-status {
      background: #f0f9ff;
      border-color: #bae6fd;
    }

    .card-status.active {
      border-color: #22b7ff;
      background: #ffffff;
      box-shadow: 0 4px 14px rgba(34, 183, 255, 0.18);
    }

    /* Data Byte Card (Orange) */
    .card-data {
      background: #fffaf5;
      border-color: #fed7aa;
    }

    .card-data.active {
      border-color: #ff9f43;
      background: #ffffff;
      box-shadow: 0 4px 14px rgba(255, 159, 67, 0.18);
    }

    .card-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 8px;
    }

    .condition-pill {
      font-size: 12px;
      font-weight: 800;
      padding: 2px 8px;
      border-radius: 6px;
      font-family: ui-monospace, monospace;
    }

    .card-status .condition-pill {
      background: #0284c7;
      color: #ffffff;
    }

    .card-data .condition-pill {
      background: #ea580c;
      color: #ffffff;
    }

    .card-title {
      font-size: 15px;
      font-weight: 800;
      color: #1e2945;
    }

    .card-range {
      font-size: 12px;
      font-weight: 700;
      font-family: ui-monospace, monospace;
      color: #475569;
      margin-bottom: 6px;
    }

    .card-desc {
      font-size: 13px;
      line-height: 1.35;
      font-weight: 600;
      color: #334155;
    }

    /* Toggle bar */
    .controls {
      display: flex;
      gap: 8px;
      width: 100%;
      justify-content: center;
    }

    .btn-toggle {
      flex: 1;
      max-width: 180px;
      padding: 9px 12px;
      font-size: 13px;
      font-weight: 700;
      border-radius: 8px;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      transition: all 0.2s ease;
    }

    .btn-toggle.active-status {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.3);
    }

    .btn-toggle.active-data {
      background: #ea580c;
      color: #ffffff;
      border-color: #ea580c;
      box-shadow: 0 2px 6px rgba(234, 88, 12, 0.3);
    }
  </style>
</head>
<body>

  <div class="main-wrap">
    
    <div class="register-container">
      <div class="register-header">
        <span class="msb-label">◀ MSB (Bit 7) — Flag</span>
        <span class="lsb-label">Bits 6–0 (Payload) ▶</span>
      </div>

      <div class="byte-grid" id="byteGrid">
        <div class="bit-box msb" id="bit7" title="Click to toggle MSB">
          <span class="bit-name">Bit 7</span>
          <span class="bit-val" id="bit7Val">1</span>
        </div>
        <div class="bit-box"><span class="bit-name">b6</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b5</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b4</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b3</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b2</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b1</span><span class="bit-val">x</span></div>
        <div class="bit-box"><span class="bit-name">b0</span><span class="bit-val">x</span></div>
      </div>
    </div>

    
    <div class="branch-tree">
      
      <div class="card-branch card-status active" id="cardStatus">
        <div class="card-header">
          <div class="card-title">Status Byte</div>
          <div class="condition-pill">MSB = 1</div>
        </div>
        <div class="card-range">128–255 · 0x80–0xFF</div>
        <div class="card-desc">Defines Command<br>&amp; MIDI Channel</div>
      </div>

      
      <div class="card-branch card-data" id="cardData">
        <div class="card-header">
          <div class="card-title">Data Byte</div>
          <div class="condition-pill">MSB = 0</div>
        </div>
        <div class="card-range">0–127 · 0x00–0x7F</div>
        <div class="card-desc">Carries Pitch, Velocity<br>or Parameter Value</div>
      </div>
    </div>

    
    <div class="controls">
      <button class="btn-toggle active-status" id="btnStatus">Status (MSB = 1)</button>
      <button class="btn-toggle" id="btnData">Data (MSB = 0)</button>
    </div>
  </div>

  <script>
    let isStatus = true;

    const bit7 = document.getElementById('bit7');
    const bit7Val = document.getElementById('bit7Val');
    const cardStatus = document.getElementById('cardStatus');
    const cardData = document.getElementById('cardData');
    const btnStatus = document.getElementById('btnStatus');
    const btnData = document.getElementById('btnData');

    function updateState(statusMode) {
      isStatus = statusMode;
      if (isStatus) {
        bit7Val.textContent = '1';
        bit7.classList.remove('is-zero');
        cardStatus.classList.add('active');
        cardData.classList.remove('active');
        btnStatus.className = 'btn-toggle active-status';
        btnData.className = 'btn-toggle';
      } else {
        bit7Val.textContent = '0';
        bit7.classList.add('is-zero');
        cardStatus.classList.remove('active');
        cardData.classList.add('active');
        btnStatus.className = 'btn-toggle';
        btnData.className = 'btn-toggle active-data';
      }
    }

    bit7.addEventListener('click', () => updateState(!isStatus));
    cardStatus.addEventListener('click', () => updateState(true));
    cardData.addEventListener('click', () => updateState(false));
    btnStatus.addEventListener('click', () => updateState(true));
    btnData.addEventListener('click', () => updateState(false));
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
    body {
      background: transparent;
      color: #1e2945;
      padding: 8px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    /* Filter Bar */
    .filter-bar {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      justify-content: center;
    }
    .filter-btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      border-radius: 20px;
      padding: 4px 10px;
      font-size: 12px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      transition: background 0.2s, color 0.2s, border-color 0.2s;
    }
    .filter-btn:hover {
      background: #e2e8f0;
      color: #1e2945;
    }
    .filter-btn.active {
      background: #1e2945;
      color: #ffffff;
      border-color: #1e2945;
    }

    /* Grid of 4 standards */
    .grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 8px;
    }
    @media (max-width: 440px) {
      .grid {
        grid-template-columns: 1fr;
      }
    }

    /* Card styling */
    .plugin-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 6px;
      transition: opacity 0.25s, box-shadow 0.2s, border-color 0.2s;
    }
    .plugin-card.dimmed {
      opacity: 0.28;
      filter: grayscale(0.6);
    }
    .plugin-card.highlight {
      border-color: #22b7ff;
      box-shadow: 0 0 0 2px rgba(34, 183, 255, 0.35);
    }

    .card-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .card-title {
      font-size: 15px;
      font-weight: 700;
      letter-spacing: -0.2px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .creator-tag {
      font-size: 10px;
      font-weight: 600;
      text-transform: uppercase;
      background: #f1f5f9;
      color: #64748b;
      padding: 2px 6px;
      border-radius: 4px;
    }

    /* Tags & Badges */
    .section-label {
      font-size: 10px;
      font-weight: 700;
      text-transform: uppercase;
      color: #94a3b8;
      margin-bottom: 2px;
    }
    .badge-row {
      display: flex;
      flex-wrap: wrap;
      gap: 4px;
    }
    .tag {
      font-size: 11px;
      font-weight: 600;
      padding: 2px 6px;
      border-radius: 5px;
      display: inline-flex;
      align-items: center;
      gap: 3px;
      line-height: 1.2;
    }
    .tag.yes {
      background: #ecfdf5;
      color: #059669;
      border: 1px solid #a7f3d0;
    }
    .tag.no {
      background: #fef2f2;
      color: #dc2626;
      border: 1px solid #fecaca;
    }
    .tag.feat {
      background: #eff6ff;
      color: #2563eb;
      border: 1px solid #bfdbfe;
      font-size: 10.5px;
    }

    /* Live compatibility indicator */
    .status-banner {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 6px 10px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      font-size: 12px;
      font-weight: 600;
    }
    .status-text {
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .status-dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: #22b7ff;
    }
  </style>
</head>
<body>

  
  <div class="filter-bar">
    <button class="filter-btn active" onclick="setFilter('all', this)">All Formats</button>
    <button class="filter-btn" onclick="setFilter('mac', this)">macOS</button>
    <button class="filter-btn" onclick="setFilter('win', this)">Windows</button>
    <button class="filter-btn" onclick="setFilter('protools', this)">Pro Tools</button>
    <button class="filter-btn" onclick="setFilter('logic', this)">Logic Pro</button>
    <button class="filter-btn" onclick="setFilter('cross', this)">Multi-DAW</button>
  </div>

  
  <div class="grid">

    
    <div class="plugin-card" id="card-vst3" data-mac="yes" data-win="yes" data-protools="no" data-logic="no" data-cross="yes">
      <div class="card-header">
        <div class="card-title">VST3 <span style="font-size:12px;color:#64748b">v3.7</span></div>
        <div class="creator-tag">Steinberg</div>
      </div>
      <div>
        <div class="section-label">OS Support</div>
        <div class="badge-row">
          <span class="tag yes">✓ Windows</span>
          <span class="tag yes">✓ macOS</span>
          <span class="tag yes">✓ Linux</span>
        </div>
      </div>
      <div>
        <div class="section-label">Compatible DAWs</div>
        <div class="badge-row">
          <span class="tag yes">✓ Ableton</span>
          <span class="tag yes">✓ Cubase</span>
          <span class="tag yes">✓ Studio One</span>
          <span class="tag yes">✓ FL Studio</span>
          <span class="tag no">✕ Pro Tools</span>
        </div>
      </div>
      <div>
        <div class="section-label">Key Architecture</div>
        <div class="badge-row">
          <span class="tag feat">⚡ Dynamic CPU Sleep</span>
        </div>
      </div>
    </div>

    
    <div class="plugin-card" id="card-au" data-mac="yes" data-win="no" data-protools="no" data-logic="yes" data-cross="no">
      <div class="card-header">
        <div class="card-title">AU <span style="font-size:12px;color:#64748b">v2 / v3</span></div>
        <div class="creator-tag">Apple</div>
      </div>
      <div>
        <div class="section-label">OS Support</div>
        <div class="badge-row">
          <span class="tag yes">✓ macOS</span>
          <span class="tag yes">✓ iOS</span>
          <span class="tag no">✕ Windows</span>
        </div>
      </div>
      <div>
        <div class="section-label">Compatible DAWs</div>
        <div class="badge-row">
          <span class="tag yes">✓ Logic Pro</span>
          <span class="tag yes">✓ GarageBand</span>
          <span class="tag yes">✓ Ableton (Mac)</span>
          <span class="tag no">✕ Pro Tools</span>
        </div>
      </div>
      <div>
        <div class="section-label">Key Architecture</div>
        <div class="badge-row">
          <span class="tag feat">⚙️ CoreAudio OS Kernel</span>
        </div>
      </div>
    </div>

    
    <div class="plugin-card" id="card-aax" data-mac="yes" data-win="yes" data-protools="yes" data-logic="no" data-cross="no">
      <div class="card-header">
        <div class="card-title">AAX <span style="font-size:12px;color:#64748b">Native / DSP</span></div>
        <div class="creator-tag">Avid</div>
      </div>
      <div>
        <div class="section-label">OS Support</div>
        <div class="badge-row">
          <span class="tag yes">✓ Windows</span>
          <span class="tag yes">✓ macOS</span>
          <span class="tag no">✕ Linux</span>
        </div>
      </div>
      <div>
        <div class="section-label">Compatible DAWs</div>
        <div class="badge-row">
          <span class="tag yes">✓ Pro Tools</span>
          <span class="tag no">✕ Logic Pro</span>
          <span class="tag no">✕ Ableton</span>
          <span class="tag no">✕ Cubase</span>
        </div>
      </div>
      <div>
        <div class="section-label">Key Architecture</div>
        <div class="badge-row">
          <span class="tag feat">🎛️ HDX Hardware DSP Sync</span>
        </div>
      </div>
    </div>

    
    <div class="plugin-card" id="card-clap" data-mac="yes" data-win="yes" data-protools="no" data-logic="no" data-cross="yes">
      <div class="card-header">
        <div class="card-title">CLAP <span style="font-size:12px;color:#64748b">Open Standard</span></div>
        <div class="creator-tag">Bitwig / u-he</div>
      </div>
      <div>
        <div class="section-label">OS Support</div>
        <div class="badge-row">
          <span class="tag yes">✓ Windows</span>
          <span class="tag yes">✓ macOS</span>
          <span class="tag yes">✓ Linux</span>
        </div>
      </div>
      <div>
        <div class="section-label">Compatible DAWs</div>
        <div class="badge-row">
          <span class="tag yes">✓ Bitwig</span>
          <span class="tag yes">✓ REAPER</span>
          <span class="tag yes">✓ FL Studio</span>
          <span class="tag no">✕ Pro Tools</span>
        </div>
      </div>
      <div>
        <div class="section-label">Key Architecture</div>
        <div class="badge-row">
          <span class="tag feat">🔀 Polyphonic Modulation</span>
        </div>
      </div>
    </div>

  </div>

  
  <div class="status-banner">
    <div class="status-text">
      <div class="status-dot" id="statusDot"></div>
      <span id="statusLabel">Showing All Standards</span>
    </div>
    <span id="matchCount" style="color:#64748b; font-size:11px;">4 of 4 Formats Active</span>
  </div>

  <script>
    const cards = document.querySelectorAll('.plugin-card');
    const statusLabel = document.getElementById('statusLabel');
    const matchCount = document.getElementById('matchCount');

    const descriptions = {
      all: 'Showing All Standards',
      mac: 'Apple macOS Compatible Formats',
      win: 'Microsoft Windows Compatible Formats',
      protools: 'Avid Pro Tools Compatible Formats',
      logic: 'Apple Logic Pro Compatible Formats',
      cross: 'Cross-DAW Production Standards'
    };

    function setFilter(filter, btn) {
      document.querySelectorAll('.filter-btn').forEach(b => b.classList.remove('active'));
      btn.classList.add('active');

      let activeCount = 0;

      cards.forEach(card => {
        if (filter === 'all') {
          card.classList.remove('dimmed');
          card.classList.remove('highlight');
          activeCount++;
        } else {
          const match = card.getAttribute('data-' + filter) === 'yes';
          if (match) {
            card.classList.remove('dimmed');
            card.classList.add('highlight');
            activeCount++;
          } else {
            card.classList.add('dimmed');
            card.classList.remove('highlight');
          }
        }
      });

      statusLabel.textContent = descriptions[filter] || 'Custom Filter';
      matchCount.textContent = activeCount + ' of 4 Formats Active';
    }
  </script>
</body>
</html>

Virtual Instrument Architectures: VST, AU, and AAX Standards

Setting Up a Digital Audio Workstation

Sampling Rate, Nyquist Theorem, and Aliasing

Bit Depth, Dynamic Range, and Dither

Audio File Formats: Uncompressed, Lossless, and Lossy

Track Types in DAWs: Audio, MIDI, Aux, Instrument, and Master

Transport Controls: Playheads, Scrubbing, and Markers

Grid Modes and Snapping: Relative, Absolute, and Shuffle

MUSTECH-4.1

Aligned learning resources

Related diagrams