Initial Commit

packages/media/audio/audio-analysis-loudness/tests/helpers/build-doc.ts

@@ -0,0 +1,65 @@
+import { AudioDocument } from "@suaveplan/audio-core";
+
+const PAGE_SIZE = 1024;
+
+/**
+ * Build an `AudioDocument` from pre-computed channel data. Splits each
+ * channel into pages of `PAGE_SIZE` samples.
+ */
+export function buildDoc(
+    channels: Float32Array[],
+    sampleRate: number
+): AudioDocument {
+    const sourceLength = channels[0]?.length ?? 0;
+    const pages: { channelData: Float32Array[]; startSample: number }[] = [];
+    for (let start = 0; start < sourceLength; start += PAGE_SIZE) {
+        const len = Math.min(PAGE_SIZE, sourceLength - start);
+        const pageData: Float32Array[] = channels.map((ch) =>
+            ch.subarray(start, start + len)
+        );
+        pages.push({ channelData: pageData, startSample: start });
+    }
+    return new AudioDocument({
+        sampleRate,
+        channels: channels.length,
+        sourceLength,
+        pages,
+    });
+}
+
+/**
+ * Generate a sine-wave channel buffer at the given amplitude, frequency, and
+ * duration. Amplitude is linear (1.0 = 0 dBFS).
+ */
+export function sine(
+    amplitude: number,
+    frequencyHz: number,
+    sampleRate: number,
+    durationSeconds: number
+): Float32Array {
+    const n = Math.round(durationSeconds * sampleRate);
+    const out = new Float32Array(n);
+    const w = (2 * Math.PI * frequencyHz) / sampleRate;
+    for (let i = 0; i < n; i++) out[i] = amplitude * Math.sin(w * i);
+    return out;
+}
+
+/** Constant-DC channel. */
+export function constant(value: number, n: number): Float32Array {
+    const out = new Float32Array(n);
+    out.fill(value);
+    return out;
+}
+
+/** Concatenate channel segments. */
+export function concat(...segments: Float32Array[]): Float32Array {
+    let total = 0;
+    for (const s of segments) total += s.length;
+    const out = new Float32Array(total);
+    let p = 0;
+    for (const s of segments) {
+        out.set(s, p);
+        p += s.length;
+    }
+    return out;
+}