lib-jitsi-meet/modules/RTC/JitsiTrack.js

var logger = require("jitsi-meet-logger").getLogger(__filename);
var RTCBrowserType = require("./RTCBrowserType");
var RTCEvents = require("../../service/RTC/RTCEvents");
var JitsiTrackEvents = require("../../JitsiTrackEvents");
var EventEmitter = require("events");
var RTC = require("./RTCUtils");

/**
 * This implements 'onended' callback normally fired by WebRTC after the stream
 * is stopped. There is no such behaviour yet in FF, so we have to add it.
 * @param jitsiTrack our track object holding the original WebRTC stream object
 * to which 'onended' handling will be added.
 */
function implementOnEndedHandling(jitsiTrack) {
    var stream = jitsiTrack.getOriginalStream();

    if(!stream)
        return;

    var originalStop = stream.stop;
    stream.stop = function () {
        originalStop.apply(stream);
        if (jitsiTrack.isActive()) {
            stream.onended();
        }
    };
}

/**
 * Adds onended/oninactive handler to a MediaStream.
 * @param mediaStream a MediaStream to attach onended/oninactive handler
 * @param handler the handler
 */
function addMediaStreamInactiveHandler(mediaStream, handler) {
    // Temasys will use onended
    if(typeof mediaStream.active !== "undefined")
        mediaStream.oninactive = handler;
    else
        mediaStream.onended = handler;
}

/**
 * Represents a single media track (either audio or video).
 * @constructor
 * @param rtc the rtc instance
 * @param stream the stream
 * @param streamInactiveHandler the function that will handle
 *        onended/oninactive events of the stream.
 * @param jitsiTrackType optionally a type can be specified.
 *        This is the case where we are creating a dummy track with no stream
 *        Currently this happens when a remote side is starting with video muted
 */
function JitsiTrack(rtc, stream, streamInactiveHandler, jitsiTrackType)
{
    /**
     * Array with the HTML elements that are displaying the streams.
     * @type {Array}
     */
    this.containers = [];
    this.rtc = rtc;
    this.stream = stream;
    this.eventEmitter = new EventEmitter();
    this.audioLevel = -1;
    this.type = jitsiTrackType || ((this.stream.getVideoTracks().length > 0)?
        JitsiTrack.VIDEO : JitsiTrack.AUDIO);
    if(this.type == JitsiTrack.AUDIO) {
        this._getTracks = function () {
            return this.stream? this.stream.getAudioTracks() : [];
        }.bind(this);
    } else {
        this._getTracks = function () {
            return this.stream? this.stream.getVideoTracks() : [];
        }.bind(this);
    }

    if(stream) {
        if (RTCBrowserType.isFirefox()) {
            implementOnEndedHandling(this);
        }
        addMediaStreamInactiveHandler(stream, streamInactiveHandler);
    }
}

/**
 * JitsiTrack video type.
 * @type {string}
 */
JitsiTrack.VIDEO = "video";

/**
 * JitsiTrack audio type.
 * @type {string}
 */
JitsiTrack.AUDIO = "audio";

/**
 * Returns the type (audio or video) of this track.
 */
JitsiTrack.prototype.getType = function() {
    return this.type;
};

/**
 * Check if this is audiotrack.
 */
JitsiTrack.prototype.isAudioTrack = function () {
    return this.getType() === JitsiTrack.AUDIO;
};

/**
 * Check if this is videotrack.
 */
JitsiTrack.prototype.isVideoTrack = function () {
    return this.getType() === JitsiTrack.VIDEO;
};

/**
 * Returns the RTCMediaStream from the browser (?).
 */
JitsiTrack.prototype.getOriginalStream = function() {
    return this.stream;
}

/**
 * Return meaningful usage label for this track depending on it's media and
 * eventual video type.
 * @returns {string}
 */
JitsiTrack.prototype.getUsageLabel = function () {
    if (this.type == JitsiTrack.AUDIO) {
        return "mic";
    } else {
        return this.videoType ? this.videoType : "default";
    }
};

/**
 * Eventually will trigger RTCEvents.TRACK_ATTACHED event.
 * @param container the video/audio container to which this stream is attached
 *        and for which event will be fired.
 * @private
 */
JitsiTrack.prototype._maybeFireTrackAttached = function (container) {
    if (this.rtc && container) {
        this.rtc.eventEmitter.emit(RTCEvents.TRACK_ATTACHED, this, container);
    }
};

/**
 * Attaches the MediaStream of this track to an HTML container.
 * Adds the container to the list of containers that are displaying the track.
 * Note that Temasys plugin will replace original audio/video element with
 * 'object' when stream is being attached to the container for the first time.
 *
 * * NOTE * if given container element is not visible when the stream is being
 * attached it will be shown back given that Temasys plugin is currently in use.
 *
 * @param container the HTML container which can be 'video' or 'audio' element.
 *        It can also be 'object' element if Temasys plugin is in use and this
 *        method has been called previously on video or audio HTML element.
 *
 * @returns potentially new instance of container if it was replaced by the
 *          library. That's the case when Temasys plugin is in use.
 */
JitsiTrack.prototype.attach = function (container) {
    if(this.stream) {
        // The container must be visible in order to play or attach the stream
        // when Temasys plugin is in use
        var containerSel = $(container);
        if (RTCBrowserType.isTemasysPluginUsed() &&
            !containerSel.is(':visible')) {
            containerSel.show();
        }
        container
            = require("./RTCUtils").attachMediaStream(container, this.stream);
    }
    this.containers.push(container);

    this._maybeFireTrackAttached(container);

    return container;
};

/**
 * Removes the track from the passed HTML container.
 * @param container the HTML container. If <tt>null</tt> all containers are removed.
 *        A container can be 'video', 'audio' or 'object' HTML element instance
 *        to which this JitsiTrack is currently attached to.
 */
JitsiTrack.prototype.detach = function (container) {
    for(var i = 0; i < this.containers.length; i++)
    {
        if(!container)
        {
            require("./RTCUtils").setVideoSrc(this.containers[i], null);
        }
        if(!container || $(this.containers[i]).is($(container)))
        {
            this.containers.splice(i,1);
        }
    }

    if(container) {
        require("./RTCUtils").setVideoSrc(container, null);
    }
}

/**
 * Dispose sending the media track. And removes it from the HTML.
 * NOTE: Works for local tracks only.
 */
JitsiTrack.prototype.dispose = function () {
}

/**
 * Returns true if this is a video track and the source of the video is a
 * screen capture as opposed to a camera.
 */
JitsiTrack.prototype.isScreenSharing = function(){

}

/**
 * Returns id of the track.
 * @returns {string} id of the track or null if this is fake track.
 */
JitsiTrack.prototype._getId = function () {
    var tracks = this.stream.getTracks();
    if(!tracks || tracks.length === 0)
        return null;
    return tracks[0].id;
};

/**
 * Returns id of the track.
 * @returns {string} id of the track or null if this is fake track.
 */
JitsiTrack.prototype.getId = function () {
    if(this.stream)
        return RTC.getStreamID(this.stream);
    else
        return null;
};

/**
 * Checks whether the MediaStream is avtive/not ended.
 * When there is no check for active we don't have information and so
 * will return that stream is active (in case of FF).
 * @returns {boolean} whether MediaStream is active.
 */
JitsiTrack.prototype.isActive = function () {
    if((typeof this.stream.active !== "undefined"))
        return this.stream.active;
    else
        return true;
};

/**
 * Attaches a handler for events(For example - "audio level changed".).
 * All possible event are defined in JitsiTrackEvents.
 * @param eventId the event ID.
 * @param handler handler for the event.
 */
JitsiTrack.prototype.on = function (eventId, handler) {
    if(this.eventEmitter)
        this.eventEmitter.on(eventId, handler);
}

/**
 * Removes event listener
 * @param eventId the event ID.
 * @param [handler] optional, the specific handler to unbind
 */
JitsiTrack.prototype.off = function (eventId, handler) {
    if(this.eventEmitter)
        this.eventEmitter.removeListener(eventId, handler);
}

// Common aliases for event emitter
JitsiTrack.prototype.addEventListener = JitsiTrack.prototype.on;
JitsiTrack.prototype.removeEventListener = JitsiTrack.prototype.off;


/**
 * Sets the audio level for the stream
 * @param audioLevel the new audio level
 */
JitsiTrack.prototype.setAudioLevel = function (audioLevel) {
    if(this.audioLevel !== audioLevel) {
        this.eventEmitter.emit(JitsiTrackEvents.TRACK_AUDIO_LEVEL_CHANGED,
            audioLevel);
        this.audioLevel = audioLevel;
    }
 }

/**
 * Returns the msid of the stream attached to the JitsiTrack object or null if
 * no stream is attached.
 */
JitsiTrack.prototype.getMSID = function () {
    var tracks, track;
    return (!this.stream || !this.stream.id || !(tracks = this._getTracks()) ||
        !tracks.length || !(track = tracks[0]) || !track.id)?
            null : this.stream.id + " " + track.id;
}

module.exports = JitsiTrack;