internal/servers/webrtc/read_index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<style>
html, body {
	margin: 0;
	padding: 0;
	height: 100%;
	font-family: 'Arial', sans-serif;
}
#video {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
	background: rgb(30, 30, 30);
}
#message {
	position: absolute;
	left: 0;
	top: 0;
	width: 100%;
	height: 100%;
	display: flex;
	align-items: center;
	text-align: center;
	justify-content: center;
	font-size: 16px;
	font-weight: bold;
	color: white;
	pointer-events: none;
	padding: 20px;
	box-sizing: border-box;
	text-shadow: 0 0 5px black;
}
</style>
</head>
<body>

<video id="video"></video>
<div id="message"></div>

<script>

const retryPause = 2000;

const video = document.getElementById('video');
const message = document.getElementById('message');

let nonAdvertisedCodecs = [];
let pc = null;
let restartTimeout = null;
let sessionUrl = '';
let offerData = '';
let queuedCandidates = [];
let defaultControls = false;

const setMessage = (str) => {
	if (str !== '') {
		video.controls = false;
	} else {
		video.controls = defaultControls;
	}
	message.innerText = str;
};

const unquoteCredential = (v) => (
	JSON.parse(`"${v}"`)
);

const linkToIceServers = (links) => (
	(links !== null) ? links.split(', ').map((link) => {
		const m = link.match(/^<(.+?)>; rel="ice-server"(; username="(.*?)"; credential="(.*?)"; credential-type="password")?/i);
		const ret = {
			urls: [m[1]],
		};

		if (m[3] !== undefined) {
			ret.username = unquoteCredential(m[3]);
			ret.credential = unquoteCredential(m[4]);
			ret.credentialType = 'password';
		}

		return ret;
	}) : []
);

const parseOffer = (sdp) => {
	const ret = {
		iceUfrag: '',
		icePwd: '',
		medias: [],
	};

	for (const line of sdp.split('\r\n')) {
		if (line.startsWith('m=')) {
			ret.medias.push(line.slice('m='.length));
		} else if (ret.iceUfrag === '' && line.startsWith('a=ice-ufrag:')) {
			ret.iceUfrag = line.slice('a=ice-ufrag:'.length);
		} else if (ret.icePwd === '' && line.startsWith('a=ice-pwd:')) {
			ret.icePwd = line.slice('a=ice-pwd:'.length);
		}
	}

	return ret;
};

const enableStereoPcmau = (section) => {
	let lines = section.split('\r\n');

	lines[0] += ' 118';
	lines.splice(lines.length - 1, 0, 'a=rtpmap:118 PCMU/8000/2');
	lines.splice(lines.length - 1, 0, 'a=rtcp-fb:118 transport-cc');

	lines[0] += ' 119';
	lines.splice(lines.length - 1, 0, 'a=rtpmap:119 PCMA/8000/2');
	lines.splice(lines.length - 1, 0, 'a=rtcp-fb:119 transport-cc');

	return lines.join('\r\n');
};

const enableMultichannelOpus = (section) => {
	let lines = section.split('\r\n');

	lines[0] += " 112";
	lines.splice(lines.length - 1, 0, "a=rtpmap:112 multiopus/48000/3");
	lines.splice(lines.length - 1, 0, "a=fmtp:112 channel_mapping=0,2,1;num_streams=2;coupled_streams=1");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:112 transport-cc");

	lines[0] += " 113";
	lines.splice(lines.length - 1, 0, "a=rtpmap:113 multiopus/48000/4");
	lines.splice(lines.length - 1, 0, "a=fmtp:113 channel_mapping=0,1,2,3;num_streams=2;coupled_streams=2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:113 transport-cc");

	lines[0] += " 114";
	lines.splice(lines.length - 1, 0, "a=rtpmap:114 multiopus/48000/5");
	lines.splice(lines.length - 1, 0, "a=fmtp:114 channel_mapping=0,4,1,2,3;num_streams=3;coupled_streams=2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:114 transport-cc");

	lines[0] += " 115";
	lines.splice(lines.length - 1, 0, "a=rtpmap:115 multiopus/48000/6");
	lines.splice(lines.length - 1, 0, "a=fmtp:115 channel_mapping=0,4,1,2,3,5;num_streams=4;coupled_streams=2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:115 transport-cc");

	lines[0] += " 116";
	lines.splice(lines.length - 1, 0, "a=rtpmap:116 multiopus/48000/7");
	lines.splice(lines.length - 1, 0, "a=fmtp:116 channel_mapping=0,4,1,2,3,5,6;num_streams=4;coupled_streams=4");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:116 transport-cc");

	lines[0] += " 117";
	lines.splice(lines.length - 1, 0, "a=rtpmap:117 multiopus/48000/8");
	lines.splice(lines.length - 1, 0, "a=fmtp:117 channel_mapping=0,6,1,4,5,2,3,7;num_streams=5;coupled_streams=4");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:117 transport-cc");

	return lines.join('\r\n');
};

const enableL16 = (section) => {
	let lines = section.split('\r\n');

	lines[0] += " 120";
	lines.splice(lines.length - 1, 0, "a=rtpmap:120 L16/8000/2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:120 transport-cc");

	lines[0] += " 121";
	lines.splice(lines.length - 1, 0, "a=rtpmap:121 L16/16000/2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:121 transport-cc");

	lines[0] += " 122";
	lines.splice(lines.length - 1, 0, "a=rtpmap:122 L16/48000/2");
	lines.splice(lines.length - 1, 0, "a=rtcp-fb:122 transport-cc");

	return lines.join('\r\n');
};

const enableStereoOpus = (section) => {
	let opusPayloadFormat = '';
	let lines = section.split('\r\n');

	for (let i = 0; i < lines.length; i++) {
		if (lines[i].startsWith('a=rtpmap:') && lines[i].toLowerCase().includes('opus/')) {
			opusPayloadFormat = lines[i].slice('a=rtpmap:'.length).split(' ')[0];
			break;
		}
	}

	if (opusPayloadFormat === '') {
		return section;
	}

	for (let i = 0; i < lines.length; i++) {
		if (lines[i].startsWith('a=fmtp:' + opusPayloadFormat + ' ')) {
			if (!lines[i].includes('stereo')) {
				lines[i] += ';stereo=1';
			}
			if (!lines[i].includes('sprop-stereo')) {
				lines[i] += ';sprop-stereo=1';
			}
		}
	}

	return lines.join('\r\n');
};

const editOffer = (sdp) => {
	const sections = sdp.split('m=');

	for (let i = 0; i < sections.length; i++) {
		if (sections[i].startsWith('audio')) {
			sections[i] = enableStereoOpus(sections[i]);

			if (nonAdvertisedCodecs.includes('pcma/8000/2')) {
				sections[i] = enableStereoPcmau(sections[i]);
			}

			if (nonAdvertisedCodecs.includes('multiopus/48000/6')) {
				sections[i] = enableMultichannelOpus(sections[i]);
			}

			if (nonAdvertisedCodecs.includes('L16/48000/2')) {
				sections[i] = enableL16(sections[i]);
			}

			break;
		}
	}

	return sections.join('m=');
};

const generateSdpFragment = (od, candidates) => {
	const candidatesByMedia = {};
	for (const candidate of candidates) {
		const mid = candidate.sdpMLineIndex;
		if (candidatesByMedia[mid] === undefined) {
			candidatesByMedia[mid] = [];
		}
		candidatesByMedia[mid].push(candidate);
	}

	let frag = 'a=ice-ufrag:' + od.iceUfrag + '\r\n'
		+ 'a=ice-pwd:' + od.icePwd + '\r\n';

	let mid = 0;

	for (const media of od.medias) {
		if (candidatesByMedia[mid] !== undefined) {
			frag += 'm=' + media + '\r\n'
				+ 'a=mid:' + mid + '\r\n';

			for (const candidate of candidatesByMedia[mid]) {
				frag += 'a=' + candidate.candidate + '\r\n';
			}
		}
		mid++;
	}

	return frag;
};

const loadStream = () => {
	requestICEServers();
};

const supportsNonAdvertisedCodec = (codec, fmtp) => (
	new Promise((resolve, reject) => {
		const pc = new RTCPeerConnection({ iceServers: [] });
		pc.addTransceiver('audio', { direction: 'recvonly' });
		pc.createOffer()
			.then((offer) => {
				if (offer.sdp.includes(' ' + codec)) { // codec is advertised, there's no need to add it manually
					resolve(false);
					return;
				}
				const sections = offer.sdp.split('m=audio');
				const lines = sections[1].split('\r\n');
				lines[0] += ' 118';
				lines.splice(lines.length - 1, 0, 'a=rtpmap:118 ' + codec);
				if (fmtp !== undefined) {
					lines.splice(lines.length - 1, 0, 'a=fmtp:118 ' + fmtp);
				}
				sections[1] = lines.join('\r\n');
				offer.sdp = sections.join('m=audio');
				return pc.setLocalDescription(offer);
			})
			.then(() => {
				return pc.setRemoteDescription(new RTCSessionDescription({
					type: 'answer',
					sdp: 'v=0\r\n'
					+ 'o=- 6539324223450680508 0 IN IP4 0.0.0.0\r\n'
					+ 's=-\r\n'
					+ 't=0 0\r\n'
					+ 'a=fingerprint:sha-256 0D:9F:78:15:42:B5:4B:E6:E2:94:3E:5B:37:78:E1:4B:54:59:A3:36:3A:E5:05:EB:27:EE:8F:D2:2D:41:29:25\r\n'
					+ 'm=audio 9 UDP/TLS/RTP/SAVPF 118\r\n'
					+ 'c=IN IP4 0.0.0.0\r\n'
					+ 'a=ice-pwd:7c3bf4770007e7432ee4ea4d697db675\r\n'
					+ 'a=ice-ufrag:29e036dc\r\n'
					+ 'a=sendonly\r\n'
					+ 'a=rtcp-mux\r\n'
					+ 'a=rtpmap:118 ' + codec + '\r\n'
					+ ((fmtp !== undefined) ? 'a=fmtp:118 ' + fmtp + '\r\n' : ''),
				}));
			})
			.then(() => {
				resolve(true);
			})
			.catch((err) => {
				resolve(false);
			})
			.finally(() => {
				pc.close();
			});
	})
);

const getNonAdvertisedCodecs = () => {
	Promise.all([
		['pcma/8000/2'],
		['multiopus/48000/6', 'channel_mapping=0,4,1,2,3,5;num_streams=4;coupled_streams=2'],
		['L16/48000/2']
	].map((c) => supportsNonAdvertisedCodec(c[0], c[1]).then((r) => (r) ? c[0] : false)))
		.then((c) => c.filter((e) => e !== false))
		.then((codecs) => {
			nonAdvertisedCodecs = codecs;
			loadStream();
		});
};

const onError = (err) => {
	if (restartTimeout === null) {
		setMessage(err + ', retrying in some seconds');

		if (pc !== null) {
			pc.close();
			pc = null;
		}

		restartTimeout = window.setTimeout(() => {
			restartTimeout = null;
			loadStream();
		}, retryPause);

		if (sessionUrl) {
			fetch(sessionUrl, {
				method: 'DELETE',
			});
		}
		sessionUrl = '';

		queuedCandidates = [];
	}
};

const sendLocalCandidates = (candidates) => {
	fetch(sessionUrl + window.location.search, {
		method: 'PATCH',
		headers: {
			'Content-Type': 'application/trickle-ice-sdpfrag',
			'If-Match': '*',
		},
		body: generateSdpFragment(offerData, candidates),
	})
		.then((res) => {
			switch (res.status) {
			case 204:
				break;
			case 404:
				throw new Error('stream not found');
			default:
				throw new Error(`bad status code ${res.status}`);
			}
		})
		.catch((err) => {
			onError(err.toString());
		});
};

const onLocalCandidate = (evt) => {
	if (restartTimeout !== null) {
		return;
	}

	if (evt.candidate !== null) {
		if (sessionUrl === '') {
			queuedCandidates.push(evt.candidate);
		} else {
			sendLocalCandidates([evt.candidate])
		}
	}
};

const onRemoteAnswer = (sdp) => {
	if (restartTimeout !== null) {
		return;
	}

	pc.setRemoteDescription(new RTCSessionDescription({
		type: 'answer',
		sdp,
	}))
		.then(() => {
			if (queuedCandidates.length !== 0) {
				sendLocalCandidates(queuedCandidates);
				queuedCandidates = [];
			}
		})
		.catch((err) => {
			onError(err.toString());
		});
};

const sendOffer = (offer) => {
	fetch(new URL('whep', window.location.href) + window.location.search, {
		method: 'POST',
		headers: {
			'Content-Type': 'application/sdp',
		},
		body: offer.sdp,
	})
		.then((res) => {
			switch (res.status) {
			case 201:
				break;
			case 404:
				throw new Error('stream not found');
			case 400:
				return res.json().then((e) => { throw new Error(e.error); });
			default:
				throw new Error(`bad status code ${res.status}`);
			}

			sessionUrl = new URL(res.headers.get('location'), window.location.href).toString();

			return res.text()
				.then((sdp) => onRemoteAnswer(sdp));
		})
		.catch((err) => {
			onError(err.toString());
		});
};

const createOffer = () => {
	pc.createOffer()
		.then((offer) => {
			offer.sdp = editOffer(offer.sdp);
			offerData = parseOffer(offer.sdp);
			pc.setLocalDescription(offer)
				.then(() => {
					sendOffer(offer);
				})
				.catch((err) => {
					onError(err.toString());
				});
		})
		.catch((err) => {
			onError(err.toString());
		});
};

const onConnectionState = () => {
	if (restartTimeout !== null) {
		return;
	}

	if (pc.iceConnectionState === 'disconnected') {
		onError('peer connection closed');
	}
};

const onTrack = (evt) => {
	setMessage('');
	video.srcObject = evt.streams[0];
};

const requestICEServers = () => {
	fetch(new URL('whep', window.location.href) + window.location.search, {
		method: 'OPTIONS',
	})
		.then((res) => {
			pc = new RTCPeerConnection({
				iceServers: linkToIceServers(res.headers.get('Link')),
				// https://webrtc.org/getting-started/unified-plan-transition-guide
				sdpSemantics: 'unified-plan',
			});

			const direction = 'sendrecv';
			pc.addTransceiver('video', { direction });
			pc.addTransceiver('audio', { direction });

			pc.onicecandidate = (evt) => onLocalCandidate(evt);
			pc.oniceconnectionstatechange = () => onConnectionState();
			pc.ontrack = (evt) => onTrack(evt);

			createOffer();
		})
		.catch((err) => {
			onError(err.toString());
		});
};

 const parseBoolString = (str, defaultVal) => {
	str = (str || '');

	if (['1', 'yes', 'true'].includes(str.toLowerCase())) {
		return true;
	}
	if (['0', 'no', 'false'].includes(str.toLowerCase())) {
		return false;
	}
	return defaultVal;
};

const loadAttributesFromQuery = () => {
	const params = new URLSearchParams(window.location.search);
	video.controls = parseBoolString(params.get('controls'), true);
	video.muted = parseBoolString(params.get('muted'), true);
	video.autoplay = parseBoolString(params.get('autoplay'), true);
	video.playsInline = parseBoolString(params.get('playsinline'), true);
	defaultControls = video.controls;
};

const init = () => {
	loadAttributesFromQuery();
	getNonAdvertisedCodecs();
};

window.addEventListener('DOMContentLoaded', init);

</script>

</body>
</html>