jitsi_app_c0/modules/simulcast/SimulcastReceiver.js

var SimulcastLogger = require("./SimulcastLogger");
var SimulcastUtils = require("./SimulcastUtils");
var MediaStreamType = require("../../service/RTC/MediaStreamTypes");

function SimulcastReceiver() {
    this.simulcastUtils = new SimulcastUtils();
    this.logger = new SimulcastLogger('SimulcastReceiver', 1);
}

SimulcastReceiver.prototype._remoteVideoSourceCache = '';
SimulcastReceiver.prototype._remoteMaps = {
    msid2Quality: {},
    ssrc2Msid: {},
    msid2ssrc: {},
    receivingVideoStreams: {}
};

SimulcastReceiver.prototype._cacheRemoteVideoSources = function (lines) {
    this._remoteVideoSourceCache = this.simulcastUtils._getVideoSources(lines);
};

SimulcastReceiver.prototype._restoreRemoteVideoSources = function (lines) {
    this.simulcastUtils._replaceVideoSources(lines, this._remoteVideoSourceCache);
};

SimulcastReceiver.prototype._ensureGoogConference = function (lines) {
    var sb;

    this.logger.info('Ensuring x-google-conference flag...')

    if (this.simulcastUtils._indexOfArray('a=x-google-flag:conference', lines) === this.simulcastUtils._emptyCompoundIndex) {
        // TODO(gp) do that for the audio as well as suggested by fippo.
        // Add the google conference flag
        sb = this.simulcastUtils._getVideoSources(lines);
        sb = ['a=x-google-flag:conference'].concat(sb);
        this.simulcastUtils._replaceVideoSources(lines, sb);
    }
};

SimulcastReceiver.prototype._restoreSimulcastGroups = function (sb) {
    this._restoreRemoteVideoSources(sb);
};

/**
 * Restores the simulcast groups of the remote description. In
 * transformRemoteDescription we remove those in order for the set remote
 * description to succeed. The focus needs the signal the groups to new
 * participants.
 *
 * @param desc
 * @returns {*}
 */
SimulcastReceiver.prototype.reverseTransformRemoteDescription = function (desc) {
    var sb;

    if (!this.simulcastUtils.isValidDescription(desc)) {
        return desc;
    }

    if (config.enableSimulcast) {
        sb = desc.sdp.split('\r\n');

        this._restoreSimulcastGroups(sb);

        desc = new RTCSessionDescription({
            type: desc.type,
            sdp: sb.join('\r\n')
        });
    }

    return desc;
};

SimulcastUtils.prototype._ensureOrder = function (lines) {
    var videoSources, sb;

    videoSources = this.parseMedia(lines, ['video'])[0];
    sb = this._compileVideoSources(videoSources);

    this._replaceVideoSources(lines, sb);
};

SimulcastReceiver.prototype._updateRemoteMaps = function (lines) {
    var remoteVideoSources = this.simulcastUtils.parseMedia(lines, ['video'])[0],
        videoSource, quality;

    // (re) initialize the remote maps.
    this._remoteMaps.msid2Quality = {};
    this._remoteMaps.ssrc2Msid = {};
    this._remoteMaps.msid2ssrc = {};

    var self = this;
    if (remoteVideoSources.groups && remoteVideoSources.groups.length !== 0) {
        remoteVideoSources.groups.forEach(function (group) {
            if (group.semantics === 'SIM' && group.ssrcs && group.ssrcs.length !== 0) {
                quality = 0;
                group.ssrcs.forEach(function (ssrc) {
                    videoSource = remoteVideoSources.sources[ssrc];
                    self._remoteMaps.msid2Quality[videoSource.msid] = quality++;
                    self._remoteMaps.ssrc2Msid[videoSource.ssrc] = videoSource.msid;
                    self._remoteMaps.msid2ssrc[videoSource.msid] = videoSource.ssrc;
                });
            }
        });
    }
};

SimulcastReceiver.prototype._setReceivingVideoStream = function (resource, ssrc) {
    this._remoteMaps.receivingVideoStreams[resource] = ssrc;
};

/**
 * Returns a stream with single video track, the one currently being
 * received by this endpoint.
 *
 * @param stream the remote simulcast stream.
 * @returns {webkitMediaStream}
 */
SimulcastReceiver.prototype.getReceivingVideoStream = function (stream) {
    var tracks, i, electedTrack, msid, quality = 0, receivingTrackId;

    var self = this;
    if (config.enableSimulcast) {

        stream.getVideoTracks().some(function (track) {
            return Object.keys(self._remoteMaps.receivingVideoStreams).some(function (resource) {
                var ssrc = self._remoteMaps.receivingVideoStreams[resource];
                var msid = self._remoteMaps.ssrc2Msid[ssrc];
                if (msid == [stream.id, track.id].join(' ')) {
                    electedTrack = track;
                    return true;
                }
            });
        });

        if (!electedTrack) {
            // we don't have an elected track, choose by initial quality.
            tracks = stream.getVideoTracks();
            for (i = 0; i < tracks.length; i++) {
                msid = [stream.id, tracks[i].id].join(' ');
                if (this._remoteMaps.msid2Quality[msid] === quality) {
                    electedTrack = tracks[i];
                    break;
                }
            }

            // TODO(gp) if the initialQuality could not be satisfied, lower
            // the requirement and try again.
        }
    }

    return (electedTrack)
        ? new webkitMediaStream([electedTrack])
        : stream;
};

SimulcastReceiver.prototype.getReceivingSSRC = function (jid) {
    var resource = Strophe.getResourceFromJid(jid);
    var ssrc = this._remoteMaps.receivingVideoStreams[resource];

    // If we haven't receiving a "changed" event yet, then we must be receiving
    // low quality (that the sender always streams).
    if(!ssrc)
    {
        var remoteStreamObject = APP.RTC.remoteStreams[jid][MediaStreamType.VIDEO_TYPE];
        var remoteStream = remoteStreamObject.getOriginalStream();
        var tracks = remoteStream.getVideoTracks();
        if (tracks) {
            for (var k = 0; k < tracks.length; k++) {
                var track = tracks[k];
                var msid = [remoteStream.id, track.id].join(' ');
                var _ssrc = this._remoteMaps.msid2ssrc[msid];
                var quality = this._remoteMaps.msid2Quality[msid];
                if (quality == 0) {
                    ssrc = _ssrc;
                }
            }
        }
    }

    return ssrc;
};

SimulcastReceiver.prototype.getReceivingVideoStreamBySSRC = function (ssrc)
{
    var sid, electedStream;
    var i, j, k;
    var jid = APP.xmpp.getJidFromSSRC(ssrc);
    if(jid && APP.RTC.remoteStreams[jid])
    {
        var remoteStreamObject = APP.RTC.remoteStreams[jid][MediaStreamType.VIDEO_TYPE];
        var remoteStream = remoteStreamObject.getOriginalStream();
        var tracks = remoteStream.getVideoTracks();
        if (tracks) {
            for (k = 0; k < tracks.length; k++) {
                var track = tracks[k];
                var msid = [remoteStream.id, track.id].join(' ');
                var tmp = this._remoteMaps.msid2ssrc[msid];
                if (tmp == ssrc) {
                    electedStream = new webkitMediaStream([track]);
                    sid = remoteStreamObject.sid;
                    // stream found, stop.
                    break;
                }
            }
        }

    }
    else
    {
        console.debug(APP.RTC.remoteStreams, jid, ssrc);
    }

    return {
        sid: sid,
        stream: electedStream
    };
};

/**
 * Gets the fully qualified msid (stream.id + track.id) associated to the
 * SSRC.
 *
 * @param ssrc
 * @returns {*}
 */
SimulcastReceiver.prototype.getRemoteVideoStreamIdBySSRC = function (ssrc) {
    return this._remoteMaps.ssrc2Msid[ssrc];
};

/**
 * Removes the ssrc-group:SIM from the remote description bacause Chrome
 * either gets confused and thinks this is an FID group or, if an FID group
 * is already present, it fails to set the remote description.
 *
 * @param desc
 * @returns {*}
 */
SimulcastReceiver.prototype.transformRemoteDescription = function (desc) {

    if (desc && desc.sdp) {
        var sb = desc.sdp.split('\r\n');

        this._updateRemoteMaps(sb);
        this._cacheRemoteVideoSources(sb);

        // NOTE(gp) this needs to be called after updateRemoteMaps because we
        // need the simulcast group in the _updateRemoteMaps() method.
        this.simulcastUtils._removeSimulcastGroup(sb);

        if (desc.sdp.indexOf('a=ssrc-group:SIM') !== -1) {
            // We don't need the goog conference flag if we're not doing
            // simulcast.
            this._ensureGoogConference(sb);
        }

        desc = new RTCSessionDescription({
            type: desc.type,
            sdp: sb.join('\r\n')
        });

        this.logger.fine(['Transformed remote description', desc.sdp].join(' '));
    }

    return desc;
};

module.exports = SimulcastReceiver;