✨ feat: Host a relay on Hetzner (#114)

We are hosting a [MoQ](https://quic.video) relay on a remote (bare
metal) server on Hetzner

With a lot of help from @victorpahuus

packages/moq/media/mp4/index.ts

@@ -0,0 +1,37 @@
+// Rename some stuff so it's on brand.
+// We need a separate file so this file can use the rename too.
+import * as MP4 from "./rename"
+export * from "./rename"
+
+export * from "./parser"
+
+export function isAudioTrack(track: MP4.Track): track is MP4.AudioTrack {
+	// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+	return (track as MP4.AudioTrack).audio !== undefined
+}
+
+export function isVideoTrack(track: MP4.Track): track is MP4.VideoTrack {
+	// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+	return (track as MP4.VideoTrack).video !== undefined
+}
+
+// TODO contribute to mp4box
+MP4.BoxParser.dOpsBox.prototype.write = function (stream: MP4.Stream) {
+	this.size = this.ChannelMappingFamily === 0 ? 11 : 13 + this.ChannelMapping!.length
+	this.writeHeader(stream)
+
+	stream.writeUint8(this.Version)
+	stream.writeUint8(this.OutputChannelCount)
+	stream.writeUint16(this.PreSkip)
+	stream.writeUint32(this.InputSampleRate)
+	stream.writeInt16(this.OutputGain)
+	stream.writeUint8(this.ChannelMappingFamily)
+
+	if (this.ChannelMappingFamily !== 0) {
+		stream.writeUint8(this.StreamCount!)
+		stream.writeUint8(this.CoupledCount!)
+		for (const mapping of this.ChannelMapping!) {
+			stream.writeUint8(mapping)
+		}
+	}
+}

packages/moq/media/mp4/parser.ts

@@ -0,0 +1,71 @@
+import * as MP4 from "./index"
+
+export interface Frame {
+	track: MP4.Track // The track this frame belongs to
+	sample: MP4.Sample // The actual sample contain the frame data
+}
+
+// Decode a MP4 container into individual samples.
+export class Parser {
+	info!: MP4.Info
+
+	#mp4 = MP4.New()
+	#offset = 0
+
+	#samples: Array<Frame> = []
+
+	constructor(init: Uint8Array) {
+		this.#mp4.onError = (err) => {
+			console.error("MP4 error", err)
+		}
+
+		this.#mp4.onReady = (info: MP4.Info) => {
+			this.info = info
+
+			// Extract all of the tracks, because we don't know if it's audio or video.
+			for (const track of info.tracks) {
+				this.#mp4.setExtractionOptions(track.id, track, { nbSamples: 1 })
+			}
+		}
+
+		this.#mp4.onSamples = (_track_id: number, track: MP4.Track, samples: MP4.Sample[]) => {
+			for (const sample of samples) {
+				this.#samples.push({ track, sample })
+			}
+		}
+
+		this.#mp4.start()
+
+		// For some reason we need to modify the underlying ArrayBuffer with offset
+		const copy = new Uint8Array(init)
+		const buffer = copy.buffer as MP4.ArrayBuffer
+		buffer.fileStart = this.#offset
+
+		this.#mp4.appendBuffer(buffer)
+		this.#offset += buffer.byteLength
+		this.#mp4.flush()
+
+		if (!this.info) {
+			throw new Error("could not parse MP4 info")
+		}
+	}
+
+	decode(chunk: Uint8Array): Array<Frame> {
+		const copy = new Uint8Array(chunk)
+
+		// For some reason we need to modify the underlying ArrayBuffer with offset
+		const buffer = copy.buffer as MP4.ArrayBuffer
+		buffer.fileStart = this.#offset
+
+		// Parse the data
+		this.#mp4.appendBuffer(buffer)
+		this.#mp4.flush()
+
+		this.#offset += buffer.byteLength
+
+		const samples = [...this.#samples]
+		this.#samples.length = 0
+
+		return samples
+	}
+}

packages/moq/media/mp4/rename.ts

@@ -0,0 +1,13 @@
+// Rename some stuff so it's on brand.
+export { createFile as New, DataStream as Stream, ISOFile, BoxParser, Log } from "mp4box"
+
+export type {
+	MP4ArrayBuffer as ArrayBuffer,
+	MP4Info as Info,
+	MP4Track as Track,
+	MP4AudioTrack as AudioTrack,
+	MP4VideoTrack as VideoTrack,
+	Sample,
+	TrackOptions,
+	SampleOptions,
+} from "mp4box"