✨ feat: Add streaming support (#125)

This adds:
- [x] Keyboard and mouse handling on the frontend
- [x] Video and audio streaming from the backend to the frontend
- [x] Input server that works with Websockets

Update - 17/11
- [ ] Master docker container to run this
- [ ] Steam runtime
- [ ] Entrypoint.sh

---------

Co-authored-by: Kristian Ollikainen <14197772+DatCaptainHorse@users.noreply.github.com>
Co-authored-by: Kristian Ollikainen <DatCaptainHorse@users.noreply.github.com>

packages/moq/karp/frame.ts

@@ -0,0 +1,64 @@
+import type { Group, GroupReader } from "../transfork/model"
+import { setVint62 } from "../transfork/stream"
+
+export type FrameType = "key" | "delta"
+
+export class Frame {
+	type: FrameType
+	timestamp: number
+	data: Uint8Array
+
+	constructor(type: FrameType, timestamp: number, data: Uint8Array) {
+		this.type = type
+		this.timestamp = timestamp
+		this.data = data
+	}
+
+	static async decode(group: GroupReader): Promise<Frame | undefined> {
+		const kind = group.index === 0 ? "key" : "delta"
+		const payload = await group.readFrame()
+		if (!payload) {
+			return undefined
+		}
+
+		const [timestamp, data] = decode_timestamp(payload)
+		return new Frame(kind, timestamp, data)
+	}
+
+	encode(group: Group) {
+		if ((group.length === 0) !== (this.type === "key")) {
+			throw new Error(`invalid ${this.type} position`)
+		}
+
+		let frame = new Uint8Array(8 + this.data.byteLength)
+		const size = setVint62(frame, BigInt(this.timestamp)).byteLength
+		frame.set(this.data, size)
+		frame = new Uint8Array(frame.buffer, 0, this.data.byteLength + size)
+
+		group.writeFrame(frame)
+	}
+}
+
+// QUIC VarInt
+function decode_timestamp(buf: Uint8Array): [number, Uint8Array] {
+	const size = 1 << ((buf[0] & 0xc0) >> 6)
+
+	const view = new DataView(buf.buffer, buf.byteOffset, size)
+	const remain = new Uint8Array(buf.buffer, buf.byteOffset + size, buf.byteLength - size)
+	let v: number
+
+	if (size === 1) {
+		v = buf[0] & 0x3f
+	} else if (size === 2) {
+		v = view.getInt16(0) & 0x3fff
+	} else if (size === 4) {
+		v = view.getUint32(0) & 0x3fffffff
+	} else if (size === 8) {
+		// NOTE: Precision loss above 2^52
+		v = Number(view.getBigUint64(0) & 0x3fffffffffffffffn)
+	} else {
+		throw new Error("impossible")
+	}
+
+	return [v, remain]
+}