Table of Contents

Пример демонстрирует проигрывание одного или нескольких потоков в нескольких качествах в одном WebRTC соединении. Единицей публикации считается комната, то есть зрители, подключившись к этой комнате, получают все опубликованные в ней потоки.

На скриншотах нижеThe example shows how to play a number of streams in one WebRTC connection with simulcast. A room is considered to be a publishing unit, that is, viewers who connect to this room receive all the streams published in it.

On the screenshots below:

Server url - Websocket URL of WCS

...

server
Room name -

...

room name
Player -

...

Image Removed

Обратите внимание, что аудио потоки проигрываются в отдельных элементах

Исходный код примера

...

viewer nickname
180p send, 360p send , 720p send -

...

quality switch buttons

Image Added

Note that audio tracks are playing in a separate audio tags.

Example source code

The source code consists of the following modules:

player.html - HTML

...

page
player.css -

...

HTML

...

page styles
player.js -

...

main application logic
config.json -

...

Анализ исходного кода

Для работы с исходным кодом примера возьмем версию файла player.js, доступную здесь

1. Локальные переменные

...

client configuration file, contains room description

Analyzing the code

To analyze the example source code, take the file player.js version available here

1. Local variables

Local variables declaration to work with constants, SFU SDK, to display video and to work with client configuration

code

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const constants = SFU.constants;
const sfu = SFU;
let mainConfig;
let remoteDisplay;
let playState;
const PLAY = "play";
const STOP = "stop";
const PRELOADER_URL="../commons/media/silence.mp3"

2.

...

Default configuration

Default room configuration to use if there is no config.json file found

code

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const defaultConfig = {
    room: {
        url: "ws://127.0.0.1:8080",
        name: "ROOM1",
        pin: "1234",
        nickName: "User1"
    }
};

3.

...

Object to store current playback state

The object should keep Websocket session data, WebRTC connection data and room data, and shoukd form HTML tags ids to access them from code.

code

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const CurrentState = function(prefix) {
    let state = {
        prefix: prefix,
        pc: null,
        session: null,
        room: null,
        roomEnded: false,
        set: function(pc, session, room) {
            state.pc = pc;
            state.session = session;
            state.room = room;
            state.roomEnded = false;
        },
        clear: function() {
            state.room = null;
            state.session = null;
            state.pc = null;
            state.roomEnded = false;
        },
        setRoomEnded: function() {
            state.roomEnded = true;
        },
        buttonId: function() {
            return state.prefix + "Btn";
        },
        buttonText: function() {
            return (state.prefix.charAt(0).toUpperCase() + state.prefix.slice(1));
        },
        inputId: function() {
            return state.prefix + "Name";
        },
        statusId: function() {
            return state.prefix + "Status";
        },
        formId: function() {
            return state.prefix + "Form";
        },
        errInfoId: function() {
            return state.prefix + "ErrorInfo";
        },
        is: function(value) {
            return (prefix === value);
        },
        isActive: function() {
            return (state.room && !state.roomEnded && state.pc);
        },
        isConnected: function() {
            return (state.session && state.session.state() === constants.SFU_STATE.CONNECTED);
        },
        isRoomEnded: function() {
            return state.roomEnded;
        }
    };
    return state;
}

4.

...

Initialization

init() codeФункция

The init()

...

function is called on page load and:

initializes state objects
reads config.json file or default configuration
initializes input fields

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const init = function() {
    let configName = getUrlParam("config") || "./config.json";
    ...
    playState = CurrentState(PLAY);
    $.getJSON(configName, function(cfg){
        mainConfig = cfg;
        onDisconnected(playState);
    }).fail(function(e){
        //use default config
        console.error("Error reading configuration file " + configName + ": " + e.status + " " + e.statusText)
        console.log("Default config will be used");
        mainConfig = defaultConfig;
        onDisconnected(playState);
    });
    $("#url").val(setURL());
    $("#roomName").val("ROOM1-"+createUUID(4));
    $("#playName").val("Player1-"+createUUID(4));
}

5.

...

Establishing server connection

connect(), SFU.createRoom() codeФункция

The connect()

...

function is called by Publish or Play click:

creates PeerConnection object
cleans the previous session state displayed
sets up room configuration and creates Websocket session
subscribes to Websocket session events

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const connect = async function(state) {
    //create peer connection
    const pc = new RTCPeerConnection();
    //get config object for room creation
    const roomConfig = getRoomConfig(mainConfig);
    roomConfig.url = $("#url").val();
    roomConfig.roomName = $("#roomName").val();
    roomConfig.nickname = $("#" + state.inputId()).val();
    // clean state display items
    setStatus(state.statusId(), "");
    setStatus(state.errInfoId(), "");
    // connect to server and create a room if not
    try {
        const session = await sfu.createRoom(roomConfig);
        // Set up session ending events
        session.on(constants.SFU_EVENT.DISCONNECTED, function() {
            onStopClick(state);
            onDisconnected(state);
            setStatus(state.statusId(), "DISCONNECTED", "green");
        }).on(constants.SFU_EVENT.FAILED, function(e) {
            onStopClick(state);
            onDisconnected(state);
            setStatus(state.statusId(), "FAILED", "red");
            if (e.status && e.statusText) {
                setStatus(state.errInfoId(), e.status + " " + e.statusText, "red");
            } else if (e.type && e.info) {
                setStatus(state.errInfoId(), e.type + ": " + e.info, "red");
            }
        });
        // Connected successfully
        onConnected(state, pc, session);
        setStatus(state.statusId(), "ESTABLISHED", "green");
    } catch(e) {
        onDisconnected(state);
        setStatus(state.statusId(), "FAILED", "red");
        setStatus(state.errInfoId(), e, "red");
    }
}

6.

...

Playback start after session establishing

onConnected() codeФункция

The onConnected() function:

...

sets up Stop button click actions
subscribes to room error events
calls playback function

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const onConnected = async function(state, pc, session) {
    state.set(pc, session, session.room());
    $("#" + state.buttonId()).text("Stop").off('click').click(function () {
        onStopClick(state);
    });
    $('#url').prop('disabled', true);
    $("#roomName").prop('disabled', true);
    $("#" + state.inputId()).prop('disabled', true);
    // Add errors displaying
    state.room.on(constants.SFU_ROOM_EVENT.FAILED, function(e) {
        setStatus(state.errInfoId(), e, "red");
        state.setRoomEnded();
        onStopClick(state);
    }).on(constants.SFU_ROOM_EVENT.OPERATION_FAILED, function (e) {
        onOperationFailed(state, e);
    }).on(constants.SFU_ROOM_EVENT.ENDED, function (e) {
        setStatus(state.errInfoId(), "Room "+state.room.name()+" has ended", "red");
        state.setRoomEnded();
        onStopClick(state);
    }).on(constants.SFU_ROOM_EVENT.DROPPED, function (e) {
        setStatus(state.errInfoId(), "Dropped from the room "+state.room.name()+" due to network issues", "red");
        state.setRoomEnded();
        onStopClick(state);
    });
    await playStreams(state);
    // Enable button after starting playback #WCS-3635
    $("#" + state.buttonId()).prop('disabled', false);
}

7.

...

Streams playback

playStreams(), SFURoom.join(), initRemoteDisplay() codeФункция

The playStreams()

...

function:

initializes a base container tag to display incoming media streams
negotiates WebRTC connection

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const playStreams = async function(state) {
    //create remote display item to show remote streams
    try {
        remoteDisplay = initDefaultRemoteDisplay(state.room, document.getElementById("remoteVideo"), {quality: true});
        // Start WebRTC negotiation
        await state.room.join(state.pc, null, null, 1);
    } catch(e) {
        if (e.type === constants.SFU_ROOM_EVENT.OPERATION_FAILED) {
            onOperationFailed(state, e);
        } else {
            console.error("Failed to play streams: " + e);
            setStatus(state.errInfoId(), e.name, "red");
            onStopClick(state);
        }
    }
}

8.

...

Playback stopping

stopStreams(), remoteDisplay.stop() code

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const stopStreams = function(state) {
    if (remoteDisplay) {
        remoteDisplay.stop();
    }
}

9.

...

Play click action

onStartClick(), playFirstSound(), connect() code

Функция The onStartClick() function:

проверяет правильность заполнения полей ввода
перед стартом воспроизведения, в браузере Safari вызывает функцию playFirstSound() для автоматического проигрывания аудио
вызывает функцию connect()validates input fields
in Safari browser, calls playFirstSound() before playback to automatically play incoming audio
calls connect() function

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const onStartClick = function(state) {
    if (validateForm("connectionForm") && validateForm(state.formId())) {
        $("#" + state.buttonId()).prop('disabled', true);
        if (state.is(PLAY) && Browser().isSafariWebRTC()) {
            playFirstSound(document.getElementById("main"), PRELOADER_URL).then(function () {
                connect(state);
            });
        } else {
            connect(state);
        }
    }
}

10.

...

Stop click actions

onStopClick(), Session.disconnect() codeФункция

The onStopClick() function:

...

stops playback
disconects Websocket session

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const onStopClick = async function(state) {
    stopStreams(state);
    if (state.isConnected()) {
        $("#" + state.buttonId()).prop('disabled', true);
        await state.session.disconnect();
        onDisconnected(state);
    }
}

11.

...

Websocket session disconnection actions

onDisconnected() codeФункция

The onDisconnected() functions:

...

sets up Play click actions
enables Server url and Room name fields access, if there's no parallel session

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const onDisconnected = function(state) {
    state.clear();
    $("#" + state.buttonId()).text(state.buttonText()).off('click').click(function () {
        onStartClick(state);
    }).prop('disabled', false);
    $('#url').prop('disabled', false);
    $("#roomName").prop('disabled', false);
    $("#" + state.inputId()).prop('disabled', false);
}

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Key

Исходный код примера

Example source code

Анализ исходного кода

1. Локальные переменные

Analyzing the code

1. Local variables

2.

Default configuration

3.

Object to store current playback state

4.

Initialization

5.

Establishing server connection

6.

Playback start after session establishing

7.

Streams playback

8.

Playback stopping

9.

Play click action

10.

Stop click actions

11.

Websocket session disconnection actions

Space shortcuts

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Page History

Versions Compared

Old Version 1

New Version Current

Key

Исходный код примера

Example source code

Анализ исходного кода

1. Локальные переменные

Analyzing the code

1. Local variables

2.

Default configuration

3.

Object to store current playback state

4.

Initialization

5.

Establishing server connection

6.

Playback start after session establishing

7.

Streams playback

8.

Playback stopping

9.

Play click action

10.

Stop click actions

11.

Websocket session disconnection actions