关于前端:WEBRTC-视频直播记录

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  • 需要:解决 RTMP/HLS/FLV 视频直播流提早
  • 背景:因为视频直播是 VR 视频直播,直播流是属于 8K 4K, 而 VR 直播流比平时的立体直播要大特地多,所以在网络散发(CDN)中会有存在提早,及 H5 播放中因为网络问题存在的流缓存导致提早增大,特地是 hls 及 flv 播放模式,网络问题越大导致的流提早越高
  • 优化指标:提早在 1s-2s(除去相机自身提早)
  • 优化计划:WEBRTC + SRS 服务
  • 链接:
    SRS:https://github.com/ossrs/srs (身为前端的我并看不懂)
    WEBRTC:https://juejin.cn/post/684490… 简略介绍
    SRSWebRTCDemo:http://ossrs.net/srs.release/… SRSwebrtc 演示

JS 资源
https://ossrs.net/players/js/…
https://ossrs.net/players/js/…
https://ossrs.net/players/js/…


  • 实时:次要说 WEBRTC 办法,
  •   <template>
            <div>
                <video id="rtc_media_player" autoplay></video>
                <!-- <video id="rtc_media_player" x-webkit-airplay='allow' webkit-playsinline playsinline controls
                x5-video-player-type='h5' x5-video-player-fullscreen x5-video-orientation='portrait' crossOrigin='Anonymous'
                allowsInlineMediaPlayback='true' autoplay></video> -->
            </div>
        </template>
    

提供一个 Video 的标签,正文外面有他的一些属性,srs 播放须要一个 video 的 ID rtc_media_player

    $(function () {
        // Async-await-promise based SRS RTC Player.
        function SrsRtcPlayerAsync() {var self = {};
            self.play = async function (url) {var conf = self.__internal.prepareUrl(url);
                self.pc.addTransceiver("audio", { direction: "recvonly"});
                self.pc.addTransceiver("video", { direction: "recvonly"});

                var offer = await self.pc.createOffer();
                await self.pc.setLocalDescription(offer);
                var session = await new Promise(function (resolve, reject) {
                    // @see https://github.com/rtcdn/rtcdn-draft
                    var data = {api: conf.apiUrl, streamurl: conf.streamUrl, clientip: null, sdp: offer.sdp};
                    console.log("Generated offer:", data);

                    $.ajax({type: "POST", url: conf.apiUrl, data: JSON.stringify(data),
                        contentType: 'application/json', dataType: 'json'
                    }).done(function (data) {console.log("Got answer:", data);
                        if (data.code) {reject(data); return;
                        }

                        resolve(data);
                    }).fail(function (reason) {reject(reason);
                    });
                });
                console.log(session)
                await self.pc.setRemoteDescription(new RTCSessionDescription({ type: 'answer', sdp: session.sdp})
                );
                return session;
            };

            // Close the publisher.
            self.close = function () {self.pc.close();
            };

            // The callback when got remote stream.
            self.onaddstream = function (event) { };

            // Internal APIs.
            self.__internal = {
                defaultPath: '/rtc/v1/play/',
                prepareUrl: function (webrtcUrl) {var urlObject = self.__internal.parse(webrtcUrl);

                    // If user specifies the schema, use it as API schema.
                    var schema = urlObject.user_query.schema;
                    schema = schema ? schema + ':' : window.location.protocol;

                    var port = urlObject.port || 1985;
                    if (schema === 'https:') {port = urlObject.port || 443;}

                    // @see https://github.com/rtcdn/rtcdn-draft
                    var api = urlObject.user_query.play || self.__internal.defaultPath;
                    if (api.lastIndexOf('/') !== api.length - 1) {api += '/';}

                    apiUrl = schema + '//' + urlObject.server + ':' + port + api;
                    for (var key in urlObject.user_query) {if (key !== 'api' && key !== 'play') {apiUrl += '&' + key + '=' + urlObject.user_query[key];
                        }
                    }
                    // Replace /rtc/v1/play/&k=v to /rtc/v1/play/?k=v
                    var apiUrl = apiUrl.replace(api + '&', api + '?');

                    var streamUrl = urlObject.url;

                    return {apiUrl: apiUrl, streamUrl: streamUrl, schema: schema, urlObject: urlObject, port: port};
                },
                parse: function (url) {
                    // @see: http://stackoverflow.com/questions/10469575/how-to-use-location-object-to-parse-url-without-redirecting-the-page-in-javascri
                    var a = document.createElement("a");
                    a.href = url.replace("rtmp://", "http://")
                        .replace("webrtc://", "http://")
                        .replace("rtc://", "http://");

                    var vhost = a.hostname;
                    var app = a.pathname.substr(1, a.pathname.lastIndexOf("/") - 1);
                    var stream = a.pathname.substr(a.pathname.lastIndexOf("/") + 1);

                    // parse the vhost in the params of app, that srs supports.
                    app = app.replace("...vhost...", "?vhost=");
                    if (app.indexOf("?") >= 0) {var params = app.substr(app.indexOf("?"));
                        app = app.substr(0, app.indexOf("?"));

                        if (params.indexOf("vhost=") > 0) {vhost = params.substr(params.indexOf("vhost=") + "vhost=".length);
                            if (vhost.indexOf("&") > 0) {vhost = vhost.substr(0, vhost.indexOf("&"));
                            }
                        }
                    }

                    // when vhost equals to server, and server is ip,
                    // the vhost is __defaultVhost__
                    if (a.hostname === vhost) {var re = /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/;
                        if (re.test(a.hostname)) {vhost = "__defaultVhost__";}
                    }

                    // parse the schema
                    var schema = "rtmp";
                    if (url.indexOf("://") > 0) {schema = url.substr(0, url.indexOf("://"));
                    }

                    var port = a.port;
                    if (!port) {if (schema === 'http') {port = 80;} else if (schema === 'https') {port = 443;} else if (schema === 'rtmp') {port = 1935;}
                    }

                    var ret = {
                        url: url,
                        schema: schema,
                        server: a.hostname, port: port,
                        vhost: vhost, app: app, stream: stream
                    };
                    self.__internal.fill_query(a.search, ret);

                    // For webrtc API, we use 443 if page is https, or schema specified it.
                    if (!ret.port) {if (schema === 'webrtc' || schema === 'rtc') {if (ret.user_query.schema === 'https') {ret.port = 443;} else if (window.location.href.indexOf('https://') === 0) {ret.port = 443;} else {
                                // For WebRTC, SRS use 1985 as default API port.
                                ret.port = 1985;
                            }
                        }
                    }

                    return ret;
                },
                fill_query: function (query_string, obj) {
                    // pure user query object.
                    obj.user_query = {};

                    if (query_string.length === 0) {return;}

                    // split again for angularjs.
                    if (query_string.indexOf("?") >= 0) {query_string = query_string.split("?")[1];
                    }

                    var queries = query_string.split("&");
                    for (var i = 0; i < queries.length; i++) {var elem = queries[i];

                        var query = elem.split("=");
                        obj[query[0]] = query[1];
                        obj.user_query[query[0]] = query[1];
                    }

                    // alias domain for vhost.
                    if (obj.domain) {obj.vhost = obj.domain;}
                }
            };

            self.pc = new RTCPeerConnection(null);
            self.pc.onaddstream = function (event) {if (self.onaddstream) {self.onaddstream(event);
                }
            };

            return self;
        }
        var sdk = null; // Global handler to do cleanup when replaying.
        var startPlay = function () {$('#rtc_media_player').show();

            // Close PC when user replay.
            if (sdk) {sdk.close();
            }

            sdk = new SrsRtcPlayerAsync();
            sdk.onaddstream = function (event) {console.log('Start play, event:', event);
                console.log(event.stream)
                $('#rtc_media_player').prop('srcObject', event.stream);
            };
            // For example:
            //      webrtc://r.ossrs.net/live/livestream
            var url = $("#txt_url").val();
            sdk.play(url).then(function (session) {$('#sessionid').html(session.sessionid);
                $('#simulator-drop').attr('href', session.simulator + '?drop=1&username=' + session.sessionid);
            }).catch(function (reason) {sdk.close();
                $('#rtc_media_player').hide();
                console.error(reason);
            });
        };

        $('#rtc_media_player').hide();
        var query = parse_query_string();

        srs_init_rtc("#txt_url", query);
        $("#txt_url").val('webrtc://47.115.33.66/live/livestream')
        $("#btn_play").click(function () {$('#rtc_media_player').prop('muted', false);
            startPlay();
            setTimeout(() => {// vrVideoinit()
            }, 1000);
        });

        if (query.autostart === 'true') {$('#rtc_media_player').prop('muted', true);
            console.warn('For autostart, we should mute it, see https://www.jianshu.com/p/c3c6944eed5a' +
                'or https://developers.google.com/web/updates/2017/09/autoplay-policy-changes#audiovideo_elements');

            startPlay();}
    });
    function vrVideoinit() {
        var scene, renderer;
        var container;
        //renderer = new THREE.WebGLRenderer();
        AVR.debug = true;
        if (!AVR.Broswer.isIE() && AVR.Broswer.webglAvailable()) {renderer = new THREE.WebGLRenderer();
        } else {renderer = new THREE.CanvasRenderer();
        }
        renderer.setPixelRatio(window.devicePixelRatio);
        container = document.getElementById('example');
        container.appendChild(renderer.domElement);
        scene = new THREE.Scene();
        // fov 选项可调整初始视频远近
        var vr = new VR(scene, renderer, container, { "fov": 90});
        //vr.playText="<img src='img/play90.png'width='40'height='40'/>";
        vr.vrbox.radius = 600;
        if (AVR.isCrossScreen()) {
            // 调整 vr 视窗偏移量
            vr.effect.separation = 1.2;
        }
        vr.loadProgressManager.onLoad = function () {
            // 视频静音
            vr.video.muted = true;
        }
        //AVR.useGyroscope=false;
        vr.init(function () {});
        var videoDom = document.getElementById('rtc_media_player')
        vr.play(videoDom, vr.resType.webrtcVideo);
        vr.video.addEventListener('canplay', function () {vr.video.play()
        })
        vr.video.crossOrigin = "Anonymous";
        vr.video.onended = function () {console.log('完结?')
            $("#example").hide()
            $(".shade").show()
            $("#iframeDoms").show()}
    }
    

SrsRtcPlayerAsync 外面是 SRS 提供内置 RTC 办法,及 RTC 解析,划重点

            self.play = async function (url) {var conf = self.__internal.prepareUrl(url);
                self.pc.addTransceiver("audio", { direction: "recvonly"});
                self.pc.addTransceiver("video", { direction: "recvonly"});

                var offer = await self.pc.createOffer();
                await self.pc.setLocalDescription(offer);
                var session = await new Promise(function (resolve, reject) {
                    // @see https://github.com/rtcdn/rtcdn-draft
                    var data = {api: conf.apiUrl, streamurl: conf.streamUrl, clientip: null, sdp: offer.sdp};
                    console.log("Generated offer:", data);
                    $.ajax({type: "POST", url: conf.apiUrl, data: JSON.stringify(data),
                        contentType: 'application/json', dataType: 'json'
                    }).done(function (data) {console.log("Got answer:", data);
                        if (data.code) {reject(data); return;
                        }

                        resolve(data);
                    }).fail(function (reason) {reject(reason);
                    });
                });
                console.log(session)
                await self.pc.setRemoteDescription(new RTCSessionDescription({ type: 'answer', sdp: session.sdp})
                );
                return session;
            };


留神 play 办法中的 apiUrl,这个地址是须要后盾提供反对的地址,也就是 SRS 服务中提供的 WEBRTC 地址,会返回一些内置办法的参数

                $('#rtc_media_player').prop('srcObject', event.stream);

这个简略 给 video 注入 media 的 Object,vrVideoinit 办法是 VR 全景播放的办法,可疏忽,局部代码提供

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