Implement Ogg demuxer

src/ogg/ogg-misc.ts

@@ -0,0 +1,32 @@
+import { toDataView } from '../misc';
+
+const OGG_CRC_POLYNOMIAL = 0x04c11db7;
+const OGG_CRC_TABLE = new Uint32Array(256);
+for (let n = 0; n < 256; n++) {
+	let crc = n << 24;
+
+	for (let k = 0; k < 8; k++) {
+		crc = (crc & 0x80000000)
+			? ((crc << 1) ^ OGG_CRC_POLYNOMIAL)
+			: (crc << 1);
+	}
+
+	OGG_CRC_TABLE[n] = (crc >>> 0) & 0xffffffff;
+}
+
+export const computeOggPageCrc = (bytes: Uint8Array) => {
+	const view = toDataView(bytes);
+
+	const originalChecksum = view.getUint32(22, true);
+	view.setUint32(22, 0, true); // Zero out checksum field
+
+	let crc = 0;
+	for (let i = 0; i < bytes.length; i++) {
+		const byte = bytes[i]!;
+		crc = ((crc << 8) ^ OGG_CRC_TABLE[(crc >>> 24) ^ byte]!) >>> 0;
+	}
+
+	view.setUint32(22, originalChecksum, true); // Restore checksum field
+
+	return crc;
+};