Clean release snapshot

2026-08-13 04:09:26 +00:00 · 2026-06-16 18:47:13 +02:00
commit 6c110398b4
574 changed files with 162566 additions and 0 deletions
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+'use strict';
+
+/**
+ * Minimal PCM WAV parser for Node.js test environments.
+ * Supports: mono/stereo, 16-bit and 24-bit signed PCM (audio format 1).
+ * Mixes all channels down to mono and returns a normalized Float32Array in [-1, 1].
+ */
+function parseWav(nodeBuffer) {
+    // Node.js Buffer.buffer is a pooled ArrayBuffer; slice to get an exact view.
+    const ab = nodeBuffer.buffer.slice(
+        nodeBuffer.byteOffset,
+        nodeBuffer.byteOffset + nodeBuffer.byteLength
+    );
+    const view = new DataView(ab);
+    const bytes = new Uint8Array(ab);
+
+    function fourCC(offset) {
+        return String.fromCharCode(bytes[offset], bytes[offset + 1], bytes[offset + 2], bytes[offset + 3]);
+    }
+
+    if (fourCC(0) !== 'RIFF' || fourCC(8) !== 'WAVE') {
+        throw new Error('Not a valid WAV file');
+    }
+
+    let audioFormat = 0, numChannels = 0, sampleRate = 0, bitsPerSample = 0;
+    let dataStart = -1, dataSize = 0;
+
+    let offset = 12;
+    while (offset + 8 <= ab.byteLength) {
+        const id = fourCC(offset);
+        const size = view.getUint32(offset + 4, true);
+        if (id === 'fmt ') {
+            audioFormat   = view.getUint16(offset + 8,  true);
+            numChannels   = view.getUint16(offset + 10, true);
+            sampleRate    = view.getUint32(offset + 12, true);
+            bitsPerSample = view.getUint16(offset + 22, true);
+        } else if (id === 'data') {
+            dataStart = offset + 8;
+            dataSize  = size;
+            break;
+        }
+        offset += 8 + size + (size & 1); // chunks are word-aligned
+    }
+
+    if (dataStart === -1) throw new Error('No data chunk found in WAV file');
+    if (audioFormat !== 1) throw new Error(`Only PCM WAV supported (audio format ${audioFormat})`);
+    if (bitsPerSample !== 16 && bitsPerSample !== 24) {
+        throw new Error(`Only 16-bit and 24-bit PCM supported (got ${bitsPerSample}-bit)`);
+    }
+
+    const bytesPerSample = bitsPerSample >> 3;
+    const bytesPerFrame = numChannels * bytesPerSample;
+    const nFrames = Math.floor(dataSize / bytesPerFrame);
+    if (dataStart + nFrames * bytesPerFrame > ab.byteLength) {
+        throw new Error('WAV data chunk extends beyond end of file');
+    }
+    const samples = new Float32Array(nFrames);
+
+    for (let i = 0; i < nFrames; i++) {
+        let sum = 0;
+        for (let ch = 0; ch < numChannels; ch++) {
+            const byteOffset = dataStart + i * bytesPerFrame + ch * bytesPerSample;
+            if (bitsPerSample === 16) {
+                sum += view.getInt16(byteOffset, true);
+            } else {
+                // 24-bit: read 3 bytes little-endian, sign-extend from bit 23.
+                const lo = bytes[byteOffset];
+                const mi = bytes[byteOffset + 1];
+                const hi = bytes[byteOffset + 2];
+                const raw = (lo | (mi << 8) | (hi << 16));
+                sum += raw & 0x800000 ? raw - 0x1000000 : raw;
+            }
+        }
+        const scale = bitsPerSample === 16 ? 32768.0 : 8388608.0;
+        samples[i] = (sum / numChannels) / scale;
+    }
+    return { samples, sampleRate };
+}
+
+module.exports = { parseWav };