Add Matroska muxer

src/misc.ts

@@ -13,3 +13,39 @@ export const last = <T>(arr: T[]) => {
 export const isU32 = (value: number) => {
 	return value >= 0 && value < 2**32;
 };
+
+export const readBits = (bytes: Uint8Array, start: number, end: number) => {
+	let result = 0;
+
+	for (let i = start; i < end; i++) {
+		let byteIndex = Math.floor(i / 8);
+		let byte = bytes[byteIndex]!;
+		let bitIndex = 0b111 - (i & 0b111);
+		let bit = (byte & (1 << bitIndex)) >> bitIndex;
+
+		result <<= 1;
+		result |= bit;
+	}
+
+	return result;
+};
+
+export const writeBits = (bytes: Uint8Array, start: number, end: number, value: number) => {
+	for (let i = start; i < end; i++) {
+		let byteIndex = Math.floor(i / 8);
+		let byte = bytes[byteIndex]!;
+		let bitIndex = 0b111 - (i & 0b111);
+
+		byte &= ~(1 << bitIndex);
+		byte |= ((value & (1 << (end - i - 1))) >> (end - i - 1)) << bitIndex;
+		bytes[byteIndex] = byte;
+	}
+};
+
+export const toUint8Array = (source: AllowSharedBufferSource): Uint8Array => {
+	if (source instanceof ArrayBuffer) {
+		return new Uint8Array(source);
+	} else {
+		return new Uint8Array(source.buffer, source.byteOffset, source.byteLength);
+	}
+};