opendaw-test/webaudio-splice-test.html at main · naomiaro/opendaw-test · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Web Audio Splice Test</title>
  <style>
    body { font-family: system-ui; background: #1a1a2e; color: #eee; padding: 40px; max-width: 800px; margin: 0 auto; }
    .drop-zone { border: 2px dashed #555; border-radius: 12px; padding: 48px; text-align: center; cursor: pointer; transition: all 0.2s; }
    .drop-zone.over { border-color: #4ade80; background: rgba(74, 222, 128, 0.1); }
    button { background: #333; color: #eee; border: 1px solid #555; padding: 8px 16px; border-radius: 6px; cursor: pointer; margin: 4px; }
    button:hover { background: #444; }
    button:disabled { opacity: 0.4; cursor: default; }
    canvas { width: 100%; height: 120px; background: #111; border-radius: 8px; cursor: crosshair; display: block; margin: 16px 0; }
    .info { color: #888; font-size: 14px; margin: 8px 0; }
    .controls { margin: 16px 0; }
    h1 { color: #4ade80; }
    #log { background: #111; padding: 12px; border-radius: 8px; font-family: monospace; font-size: 12px; max-height: 200px; overflow-y: auto; white-space: pre-wrap; }
  </style>
</head>
<body>
  <h1>Web Audio Splice Test</h1>
  <p class="info">Debug tool: tests if splitting an audio buffer into two consecutive AudioBufferSourceNodes produces a click at the splice point. No SDK involved — pure Web Audio API.</p>

  <div class="drop-zone" id="dropZone">
    <p style="font-size: 20px">Drop an audio file here</p>
    <p class="info">or click to browse</p>
    <input type="file" accept="audio/*" id="fileInput" style="display:none">
  </div>

  <div id="ui" style="display:none">
    <canvas id="waveform"></canvas>
    <p class="info">Click = position playhead. Shift+Click = add split (red line). Play to hear across splice points.</p>
    <div class="controls">
      <label style="font-size: 14px; color: #aaa;">Fade samples: <input type="number" id="fadeSamples" value="128" min="0" max="8192" step="64" style="width:70px; background:#222; color:#eee; border:1px solid #555; padding:4px 8px; border-radius:4px;"></label>
      <span class="info" id="fadeMs"></span>
      <label style="font-size: 14px; color: #aaa; margin-left: 12px;"><input type="checkbox" id="overlapMode" checked> Overlap crossfade</label>
      <button id="play">Play</button>
      <button id="stop">Stop</button>
    </div>
    <p class="info" id="splitInfo">Split point: none</p>
    <div id="log"></div>
  </div>

  <script>
    let audioCtx = null;
    let audioBuffer = null;
    let splits = []; // array of sample indices where splits occur
    let playheadSample = 0;
    let currentSources = [];
    let isPlaying = false;
    let playStartTime = 0;
    let playStartSample = 0;
    let animFrameId = null;

    const log = (msg) => {
      const el = document.getElementById('log');
      el.textContent += msg + '\n';
      el.scrollTop = el.scrollHeight;
    };

    const dropZone = document.getElementById('dropZone');
    const fileInput = document.getElementById('fileInput');

    dropZone.addEventListener('click', () => fileInput.click());
    dropZone.addEventListener('dragover', (e) => { e.preventDefault(); dropZone.classList.add('over'); });
    dropZone.addEventListener('dragleave', () => dropZone.classList.remove('over'));
    dropZone.addEventListener('drop', (e) => {
      e.preventDefault();
      dropZone.classList.remove('over');
      const file = e.dataTransfer.files[0];
      if (file) loadFile(file);
    });
    fileInput.addEventListener('change', (e) => {
      if (e.target.files[0]) loadFile(e.target.files[0]);
    });

    async function loadFile(file) {
      if (!audioCtx) audioCtx = new AudioContext();
      log(`Decoding ${file.name} (${(file.size / 1024 / 1024).toFixed(1)} MB)...`);
      try {
        const arrayBuffer = await file.arrayBuffer();
        audioBuffer = await audioCtx.decodeAudioData(arrayBuffer);
      } catch (e) {
        log(`Error: Could not decode "${file.name}". ${e.message || e}`);
        return;
      }
      log(`Decoded: ${audioBuffer.duration.toFixed(2)}s, ${audioBuffer.sampleRate}Hz, ${audioBuffer.numberOfChannels}ch, ${audioBuffer.length} samples`);

      splits = [];
      playheadSample = 0;
      dropZone.style.display = 'none';
      document.getElementById('ui').style.display = 'block';
      updateSplitInfo();
      updateFadeMs();
      // Wait a frame for layout to resolve before drawing
      requestAnimationFrame(() => drawWaveform());
    }

    window.addEventListener('resize', () => {
      if (audioBuffer) drawWaveform();
    });

    function updateSplitInfo() {
      const playSeconds = playheadSample / audioBuffer.sampleRate;
      document.getElementById('splitInfo').textContent =
        `Playhead: ${playSeconds.toFixed(3)}s | ${splits.length} split${splits.length !== 1 ? 's' : ''} → ${splits.length + 1} region${splits.length > 0 ? 's' : ''}`;
    }

    function drawWaveform() {
      const canvas = document.getElementById('waveform');
      const ctx = canvas.getContext('2d');
      const dpr = window.devicePixelRatio || 1;
      canvas.width = canvas.clientWidth * dpr;
      canvas.height = canvas.clientHeight * dpr;
      ctx.scale(dpr, dpr);
      const w = canvas.clientWidth;
      const h = canvas.clientHeight;

      ctx.fillStyle = '#111';
      ctx.fillRect(0, 0, w, h);

      // Draw waveform (channel 0)
      const data = audioBuffer.getChannelData(0);
      const step = Math.ceil(data.length / w);
      ctx.fillStyle = '#4ade80';
      for (let x = 0; x < w; x++) {
        const start = x * step;
        let min = 0, max = 0;
        for (let j = start; j < start + step && j < data.length; j++) {
          if (data[j] < min) min = data[j];
          if (data[j] > max) max = data[j];
        }
        const yMin = (1 + min) * h / 2;
        const yMax = (1 + max) * h / 2;
        ctx.fillRect(x, yMax, 1, yMin - yMax);
      }

      // Draw split lines (red dashed)
      ctx.strokeStyle = 'rgba(255, 180, 80, 0.8)';
      ctx.lineWidth = 1.5;
      ctx.setLineDash([4, 4]);
      for (const s of splits) {
        const x = (s / audioBuffer.length) * w;
        ctx.beginPath();
        ctx.moveTo(x, 0);
        ctx.lineTo(x, h);
        ctx.stroke();
      }
      ctx.setLineDash([]);

      // Draw playhead (white solid)
      const phX = (playheadSample / audioBuffer.length) * w;
      ctx.strokeStyle = '#fff';
      ctx.lineWidth = 2;
      ctx.beginPath();
      ctx.moveTo(phX, 0);
      ctx.lineTo(phX, h);
      ctx.stroke();
    }

    document.getElementById('waveform').addEventListener('click', (e) => {
      if (!audioBuffer || isPlaying) return;
      const rect = e.target.getBoundingClientRect();
      const fraction = (e.clientX - rect.left) / rect.width;
      const sample = Math.round(fraction * audioBuffer.length);

      if (e.shiftKey) {
        // Shift+Click = add split
        splits.push(sample);
        splits.sort((a, b) => a - b);
        log(`Split added at sample ${sample} (${(sample / audioBuffer.sampleRate).toFixed(4)}s) — ${splits.length + 1} regions`);
      } else {
        // Click = position playhead
        playheadSample = sample;
      }

      updateSplitInfo();
      drawWaveform();
    });

    function stopAll() {
      currentSources.forEach(s => { try { s.stop(); } catch(e) { if (e.name !== 'InvalidStateError') console.warn('Error stopping source:', e); } });
      currentSources = [];
      isPlaying = false;
      if (animFrameId) { cancelAnimationFrame(animFrameId); animFrameId = null; }
    }

    function updatePlayhead() {
      if (!isPlaying) return;
      const elapsed = audioCtx.currentTime - playStartTime;
      playheadSample = Math.min(playStartSample + Math.round(elapsed * audioBuffer.sampleRate), audioBuffer.length);
      drawWaveform();
      updateSplitInfo();
      if (playheadSample >= audioBuffer.length) { stopAll(); return; }
      animFrameId = requestAnimationFrame(updatePlayhead);
    }

    document.getElementById('stop').addEventListener('click', () => {
      stopAll();
      drawWaveform();
    });

    // Update fade ms display
    function updateFadeMs() {
      const samples = parseInt(document.getElementById('fadeSamples').value) || 0;
      const sr = audioBuffer ? audioBuffer.sampleRate : 48000;
      document.getElementById('fadeMs').textContent = `(${(samples / sr * 1000).toFixed(1)}ms)`;
    }
    document.getElementById('fadeSamples').addEventListener('input', updateFadeMs);

    // Play: schedule consecutive AudioBufferSourceNodes with optional crossfade
    document.getElementById('play').addEventListener('click', async () => {
      if (!audioBuffer) return;
      stopAll();
      if (audioCtx.state === 'suspended') await audioCtx.resume();

      const fadeSamples = parseInt(document.getElementById('fadeSamples').value) || 0;
      const overlap = document.getElementById('overlapMode').checked;
      const sr = audioBuffer.sampleRate;
      const fadeDur = fadeSamples / sr;

      // Build region boundaries from splits
      const boundaries = [0, ...splits, audioBuffer.length];

      // Find which region the playhead is in
      let startRegion = 0;
      for (let i = 0; i < boundaries.length - 1; i++) {
        if (playheadSample < boundaries[i + 1]) { startRegion = i; break; }
      }

      const now = audioCtx.currentTime + 0.05;
      let scheduleTime = now;

      const playheadOffset = playheadSample / sr;
      const hasFade = fadeSamples > 0 && splits.length > 0;
      const mode = hasFade ? (overlap ? 'overlap crossfade' : 'non-overlap fade') : 'no fade';

      log(`Playing from ${playheadOffset.toFixed(4)}s across ${boundaries.length - 1 - startRegion} region(s) [${mode}${hasFade ? `, ${fadeSamples} samples / ${(fadeDur * 1000).toFixed(1)}ms` : ''}]`);

      for (let i = startRegion; i < boundaries.length - 1; i++) {
        const regionStartSample = boundaries[i];
        const regionEndSample = boundaries[i + 1];
        const regionStartSec = regionStartSample / sr;
        const regionEndSec = regionEndSample / sr;
        const isFirst = i === startRegion;
        const isLast = i === boundaries.length - 2;

        // For first region, start from playhead position
        const offsetSec = isFirst ? playheadOffset : regionStartSec;

        if (hasFade && overlap) {
          // OVERLAP MODE: extend each region by fadeDur, crossfade during overlap
          // Left region plays fadeDur longer, right region starts fadeDur earlier
          const extendEnd = (!isLast) ? fadeDur : 0;
          const earlyStart = (!isFirst) ? fadeDur : 0;
          const srcOffset = offsetSec - earlyStart;
          const srcDuration = (regionEndSec - offsetSec) + extendEnd + earlyStart;

          if (srcDuration <= 0) continue;

          const source = audioCtx.createBufferSource();
          source.buffer = audioBuffer;
          const gain = audioCtx.createGain();
          source.connect(gain).connect(audioCtx.destination);

          const regionScheduleTime = scheduleTime - earlyStart;

          // Fade-in at the start (except first region)
          if (!isFirst) {
            gain.gain.setValueAtTime(0, regionScheduleTime);
            gain.gain.linearRampToValueAtTime(1, regionScheduleTime + fadeDur);
          }

          // Fade-out at the end (except last region)
          if (!isLast) {
            const fadeOutStart = scheduleTime + (regionEndSec - offsetSec);
            gain.gain.setValueAtTime(1, fadeOutStart);
            gain.gain.linearRampToValueAtTime(0, fadeOutStart + fadeDur);
          }

          source.start(regionScheduleTime, srcOffset, srcDuration);
          currentSources.push(source);

          log(`  region ${i}: offset=${srcOffset.toFixed(4)}s dur=${srcDuration.toFixed(4)}s @ t+${(regionScheduleTime - now).toFixed(4)}s${!isFirst ? ' (early start)' : ''}${!isLast ? ' (extended end)' : ''}`);
          scheduleTime += (regionEndSec - offsetSec);

        } else if (hasFade && !overlap) {
          // NON-OVERLAP MODE: fade-out/fade-in at boundaries, no overlap
          const durationSec = regionEndSec - offsetSec;
          if (durationSec <= 0) continue;

          const source = audioCtx.createBufferSource();
          source.buffer = audioBuffer;
          const gain = audioCtx.createGain();
          source.connect(gain).connect(audioCtx.destination);

          if (!isLast) {
            const fadeOutStart = scheduleTime + durationSec - fadeDur;
            gain.gain.setValueAtTime(1, fadeOutStart);
            gain.gain.linearRampToValueAtTime(0, fadeOutStart + fadeDur);
          }
          if (!isFirst) {
            gain.gain.setValueAtTime(0, scheduleTime);
            gain.gain.linearRampToValueAtTime(1, scheduleTime + fadeDur);
          }

          source.start(scheduleTime, offsetSec, durationSec);
          currentSources.push(source);

          log(`  region ${i}: ${offsetSec.toFixed(4)}s — ${regionEndSec.toFixed(4)}s @ t+${(scheduleTime - now).toFixed(4)}s`);
          scheduleTime += durationSec;

        } else {
          // NO FADE: simple consecutive scheduling
          const durationSec = regionEndSec - offsetSec;
          if (durationSec <= 0) continue;

          const source = audioCtx.createBufferSource();
          source.buffer = audioBuffer;
          source.connect(audioCtx.destination);
          source.start(scheduleTime, offsetSec, durationSec);
          currentSources.push(source);

          log(`  region ${i}: ${offsetSec.toFixed(4)}s — ${regionEndSec.toFixed(4)}s @ t+${(scheduleTime - now).toFixed(4)}s`);
          scheduleTime += durationSec;
        }
      }

      isPlaying = true;
      playStartTime = now;
      playStartSample = playheadSample;
      animFrameId = requestAnimationFrame(updatePlayhead);
    });
  </script>
</body>
</html>