'use strict';
/**
* @callback OnError
* @param {string} err - error.
*/
/**
* @callback OnTrack
* @param {RTCTrackEvent} evt - track event.
*/
/**
* @typedef Conf
* @type {object}
* @property {string} url - absolute URL of the WHEP endpoint.
* @property {string} user - username.
* @property {string} pass - password.
* @property {string} token - token.
* @property {OnError} onError - called when there's an error.
* @property {OnTrack} onTrack - called when there's a track available.
*/
/** WebRTC/WHEP reader. */
class MediaMTXWebRTCReader {
/**
* Create a MediaMTXWebRTCReader.
* @param {Conf} conf - configuration.
*/
constructor(conf) {
this.retryPause = 2000;
this.conf = conf;
this.state = 'getting_codecs';
this.restartTimeout = null;
this.pc = null;
this.offerData = null;
this.sessionUrl = null;
this.queuedCandidates = [];
this.#getNonAdvertisedCodecs();
}
/**
* Close the reader and all its resources.
*/
close() {
this.state = 'closed';
if (this.pc !== null) {
this.pc.close();
}
if (this.restartTimeout !== null) {
clearTimeout(this.restartTimeout);
}
}
static #supportsNonAdvertisedCodec(codec, fmtp) {
return new Promise((resolve) => {
const pc = new RTCPeerConnection({ iceServers: [] });
const mediaType = 'audio';
let payloadType = '';
pc.addTransceiver(mediaType, { direction: 'recvonly' });
pc.createOffer()
.then((offer) => {
if (offer.sdp === undefined) {
throw new Error('SDP not present');
}
if (offer.sdp.includes(` ${codec}`)) { // codec is advertised, there's no need to add it manually
throw new Error('already present');
}
const sections = offer.sdp.split(`m=${mediaType}`);
const payloadTypes = sections.slice(1)
.map((s) => s.split('\r\n')[0].split(' ').slice(3))
.reduce((prev, cur) => [...prev, ...cur], []);
payloadType = this.#reservePayloadType(payloadTypes);
const lines = sections[1].split('\r\n');
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} ${codec}`);
if (fmtp !== undefined) {
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} ${fmtp}`);
}
sections[1] = lines.join('\r\n');
offer.sdp = sections.join(`m=${mediaType}`);
return pc.setLocalDescription(offer);
})
.then(() => (
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=${mediaType} 9 UDP/TLS/RTP/SAVPF ${payloadType}\r\n`
+ 'c=IN IP4 0.0.0.0\r\n'
+ 'a=ice-pwd:7c3bf4770007e7432ee4ea4d697db675\r\n'
+ 'a=ice-ufrag:29e036dc\r\n'
+ 'a=sendonly\r\n'
+ 'a=rtcp-mux\r\n'
+ `a=rtpmap:${payloadType} ${codec}\r\n`
+ ((fmtp !== undefined) ? `a=fmtp:${payloadType} ${fmtp}\r\n` : ''),
}))
))
.then(() => {
resolve(true);
})
.catch(() => {
resolve(false);
})
.finally(() => {
pc.close();
});
});
}
static #unquoteCredential(v) {
return JSON.parse(`"${v}"`);
}
static #linkToIceServers(links) {
return (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 = this.#unquoteCredential(m[3]);
ret.credential = this.#unquoteCredential(m[4]);
ret.credentialType = 'password';
}
return ret;
}) : [];
}
static #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;
}
static #reservePayloadType(payloadTypes) {
// everything is valid between 30 and 127, except for interval between 64 and 95
// https://chromium.googlesource.com/external/webrtc/+/refs/heads/master/call/payload_type.h#29
for (let i = 30; i <= 127; i++) {
if ((i <= 63 || i >= 96) && !payloadTypes.includes(i.toString())) {
const pl = i.toString();
payloadTypes.push(pl);
return pl;
}
}
throw Error('unable to find a free payload type');
}
static #enableStereoPcmau(payloadTypes, section) {
const lines = section.split('\r\n');
let payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} PCMU/8000/2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} PCMA/8000/2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
return lines.join('\r\n');
}
static #enableMultichannelOpus(payloadTypes, section) {
const lines = section.split('\r\n');
let payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/3`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,2,1;num_streams=2;coupled_streams=1`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/4`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,1,2,3;num_streams=2;coupled_streams=2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/5`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,4,1,2,3;num_streams=3;coupled_streams=2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/6`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,4,1,2,3,5;num_streams=4;coupled_streams=2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/7`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,4,1,2,3,5,6;num_streams=4;coupled_streams=4`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} multiopus/48000/8`);
lines.splice(lines.length - 1, 0, `a=fmtp:${payloadType} channel_mapping=0,6,1,4,5,2,3,7;num_streams=5;coupled_streams=4`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
return lines.join('\r\n');
}
static #enableL16(payloadTypes, section) {
const lines = section.split('\r\n');
let payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} L16/8000/2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} L16/16000/2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
payloadType = this.#reservePayloadType(payloadTypes);
lines[0] += ` ${payloadType}`;
lines.splice(lines.length - 1, 0, `a=rtpmap:${payloadType} L16/48000/2`);
lines.splice(lines.length - 1, 0, `a=rtcp-fb:${payloadType} transport-cc`);
return lines.join('\r\n');
}
static #enableStereoOpus(section) {
let opusPayloadFormat = '';
const lines = section.split('\r\n');
for (let i = 0; i < lines.length; i++) {
if (lines[i].startsWith('a=rtpmap:') && lines[i].toLowerCase().includes('opus/')) {
opusPayloadFormat = lines[i].slice('a=rtpmap:'.length).split(' ')[0];
break;
}
}
if (opusPayloadFormat === '') {
return section;
}
for (let i = 0; i < lines.length; i++) {
if (lines[i].startsWith(`a=fmtp:${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');
}
static #editOffer(sdp, nonAdvertisedCodecs) {
const sections = sdp.split('m=');
const payloadTypes = sections.slice(1)
.map((s) => s.split('\r\n')[0].split(' ').slice(3))
.reduce((prev, cur) => [...prev, ...cur], []);
for (let i = 1; i < sections.length; i++) {
if (sections[i].startsWith('audio')) {
sections[i] = this.#enableStereoOpus(sections[i]);
if (nonAdvertisedCodecs.includes('pcma/8000/2')) {
sections[i] = this.#enableStereoPcmau(payloadTypes, sections[i]);
}
if (nonAdvertisedCodecs.includes('multiopus/48000/6')) {
sections[i] = this.#enableMultichannelOpus(payloadTypes, sections[i]);
}
if (nonAdvertisedCodecs.includes('L16/48000/2')) {
sections[i] = this.#enableL16(payloadTypes, sections[i]);
}
break;
}
}
return sections.join('m=');
}
static #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=${candidate.candidate}\r\n`;
}
}
mid++;
}
return frag;
}
#handleError(err) {
if (this.state === 'running') {
if (this.pc !== null) {
this.pc.close();
this.pc = null;
}
this.offerData = null;
if (this.sessionUrl !== null) {
fetch(this.sessionUrl, {
method: 'DELETE',
});
this.sessionUrl = null;
}
this.queuedCandidates = [];
this.state = 'restarting';
this.restartTimeout = window.setTimeout(() => {
this.restartTimeout = null;
this.state = 'running';
this.#start();
}, this.retryPause);
if (this.conf.onError !== undefined) {
this.conf.onError(`${err}, retrying in some seconds`);
}
} else if (this.state === 'getting_codecs') {
this.state = 'failed';
if (this.conf.onError !== undefined) {
this.conf.onError(err);
}
}
}
#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) => MediaMTXWebRTCReader.#supportsNonAdvertisedCodec(c[0], c[1]).then((r) => ((r) ? c[0] : false))))
.then((c) => c.filter((e) => e !== false))
.then((codecs) => {
if (this.state !== 'getting_codecs') {
throw new Error('closed');
}
this.nonAdvertisedCodecs = codecs;
this.state = 'running';
this.#start();
})
.catch((err) => {
this.#handleError(err);
});
}
#start() {
this.#requestICEServers()
.then((iceServers) => this.#setupPeerConnection(iceServers))
.then((offer) => this.#sendOffer(offer))
.then((answer) => this.#setAnswer(answer))
.catch((err) => {
this.#handleError(err.toString());
});
}
#authHeader() {
if (this.conf.user !== undefined && this.conf.user !== '') {
const credentials = btoa(`${this.conf.user}:${this.conf.pass}`);
return {'Authorization': `Basic ${credentials}`};
}
if (this.conf.token !== undefined && this.conf.token !== '') {
return {'Authorization': `Bearer ${this.conf.token}`};
}
return {};
}
#requestICEServers() {
return fetch(this.conf.url, {
method: 'OPTIONS',
headers: {
...this.#authHeader(),
},
})
.then((res) => MediaMTXWebRTCReader.#linkToIceServers(res.headers.get('Link')));
}
#setupPeerConnection(iceServers) {
if (this.state !== 'running') {
throw new Error('closed');
}
this.pc = new RTCPeerConnection({
iceServers,
// https://webrtc.org/getting-started/unified-plan-transition-guide
sdpSemantics: 'unified-plan',
});
const direction = 'recvonly';
this.pc.addTransceiver('video', { direction });
this.pc.addTransceiver('audio', { direction });
this.pc.onicecandidate = (evt) => this.#onLocalCandidate(evt);
this.pc.onconnectionstatechange = () => this.#onConnectionState();
this.pc.ontrack = (evt) => this.#onTrack(evt);
return this.pc.createOffer()
.then((offer) => {
offer.sdp = MediaMTXWebRTCReader.#editOffer(offer.sdp, this.nonAdvertisedCodecs);
this.offerData = MediaMTXWebRTCReader.#parseOffer(offer.sdp);
return this.pc.setLocalDescription(offer)
.then(() => offer.sdp);
});
}
#sendOffer(offer) {
if (this.state !== 'running') {
throw new Error('closed');
}
return fetch(this.conf.url, {
method: 'POST',
headers: {
...this.#authHeader(),
'Content-Type': 'application/sdp',
},
body: offer,
})
.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}`);
}
this.sessionUrl = new URL(res.headers.get('location'), this.conf.url).toString();
return res.text();
});
}
#setAnswer(answer) {
if (this.state !== 'running') {
throw new Error('closed');
}
return this.pc.setRemoteDescription(new RTCSessionDescription({
type: 'answer',
sdp: answer,
}))
.then(() => {
if (this.state !== 'running') {
return;
}
if (this.queuedCandidates.length !== 0) {
this.#sendLocalCandidates(this.queuedCandidates);
this.queuedCandidates = [];
}
});
}
#onLocalCandidate(evt) {
if (this.state !== 'running') {
return;
}
if (evt.candidate !== null) {
if (this.sessionUrl === null) {
this.queuedCandidates.push(evt.candidate);
} else {
this.#sendLocalCandidates([evt.candidate]);
}
}
}
#sendLocalCandidates(candidates) {
fetch(this.sessionUrl, {
method: 'PATCH',
headers: {
'Content-Type': 'application/trickle-ice-sdpfrag',
'If-Match': '*',
},
body: MediaMTXWebRTCReader.#generateSdpFragment(this.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) => {
this.#handleError(err.toString());
});
}
#onConnectionState() {
if (this.state !== 'running') {
return;
}
// "closed" can arrive before "failed" and without
// the close() method being called at all.
// It happens when the other peer sends a termination
// message like a DTLS CloseNotify.
if (this.pc.connectionState === 'failed'
|| this.pc.connectionState === 'closed'
) {
this.#handleError('peer connection closed');
}
}
#onTrack(evt) {
if (this.conf.onTrack !== undefined) {
this.conf.onTrack(evt);
}
}
}
window.MediaMTXWebRTCReader = MediaMTXWebRTCReader;