112 lines
3.1 KiB
JavaScript
112 lines
3.1 KiB
JavaScript
import MediaStreamUtils from '/imports/utils/media-stream-utils';
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export default class LocalPCLoopback {
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constructor(constraints) {
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this.constraints = constraints;
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this.inputStream = null;
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this.localPC = null;
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this.loopbackPC = null;
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this.loopbackStream = new MediaStream();
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}
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_initializeLocalPC() {
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this.localPC = new RTCPeerConnection();
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this.localPC.onicecandidate = (({ candidate }) => {
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if (candidate && this.loopbackPC) {
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this.loopbackPC.addIceCandidate(new RTCIceCandidate(candidate));
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}
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});
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this.inputStream.getTracks().forEach((track) => this.localPC.addTrack(track, this.inputStream));
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}
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_initializeLoopbackPC() {
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this.loopbackPC = new RTCPeerConnection();
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this.loopbackPC.onicecandidate = (({ candidate }) => {
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if (candidate && this.localPC) {
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this.localPC.addIceCandidate(new RTCIceCandidate(candidate));
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}
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});
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this.loopbackPC.ontrack = (({ streams }) => {
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streams.forEach((stream) => {
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stream.getTracks().forEach((track) => this.loopbackStream.addTrack(track));
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});
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});
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}
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_replaceInputStream(inputStream) {
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let replaced = false;
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if (this.localPC == null || inputStream == null || !inputStream?.active) {
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return Promise.resolve(this.loopbackStream);
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}
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const newTracks = {
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audio: inputStream.getAudioTracks(),
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video: inputStream.getVideoTracks(),
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};
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this.localPC.getSenders().forEach((sender, index) => {
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if (sender.track) {
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const { kind } = sender.track;
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if (this.constraints[kind]) {
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const newTrack = newTracks[kind][index];
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if (newTrack == null) return;
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sender.replaceTrack(newTrack);
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replaced = true;
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}
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}
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});
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if (replaced) this.inputStream = inputStream;
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return Promise.resolve(this.loopbackStream);
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}
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async start(inputStream) {
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if (inputStream == null || !inputStream?.active) throw (new TypeError('Invalid input stream'));
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if (this.localPC && this.loopbackPC) return this._replaceInputStream(inputStream);
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this.inputStream = inputStream;
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const nOptions = {
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offerAudio: this.constraints.audio,
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offerVideo: this.constraints.video,
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offerToReceiveAudio: false,
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offerToReceiveVideo: false,
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};
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try {
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this._initializeLocalPC();
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this._initializeLoopbackPC();
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const offer = await this.localPC.createOffer(nOptions);
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await this.localPC.setLocalDescription(offer);
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await this.loopbackPC.setRemoteDescription(offer);
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const answer = await this.loopbackPC.createAnswer();
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await this.loopbackPC.setLocalDescription(answer);
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await this.localPC.setRemoteDescription(answer);
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return this.loopbackStream;
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} catch (error) {
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// Rollback
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this.stop();
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throw error;
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}
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}
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stop() {
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if (this.localPC) {
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this.localPC.close();
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this.localPC = null;
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}
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if (this.loopbackPC) {
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this.loopbackPC.close();
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this.loopbackPC = null;
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}
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if (this.loopbackStream) {
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MediaStreamUtils.stopMediaStreamTracks(this.loopbackStream);
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this.loopbackStream = null;
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}
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}
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}
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