jiti-meet/modules/xmpp/SDPDiffer.js

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function SDPDiffer(mySDP, otherSDP) {
this.mySDP = mySDP;
this.otherSDP = otherSDP;
}
/**
* Returns map of MediaChannel that contains only media not contained in <tt>otherSdp</tt>. Mapped by channel idx.
* @param otherSdp the other SDP to check ssrc with.
*/
SDPDiffer.prototype.getNewMedia = function() {
// this could be useful in Array.prototype.
function arrayEquals(array) {
// if the other array is a falsy value, return
if (!array)
return false;
// compare lengths - can save a lot of time
if (this.length != array.length)
return false;
for (var i = 0, l=this.length; i < l; i++) {
// Check if we have nested arrays
if (this[i] instanceof Array && array[i] instanceof Array) {
// recurse into the nested arrays
if (!this[i].equals(array[i]))
return false;
}
else if (this[i] != array[i]) {
// Warning - two different object instances will never be equal: {x:20} != {x:20}
return false;
}
}
return true;
}
var myMedias = this.mySDP.getMediaSsrcMap();
var othersMedias = this.otherSDP.getMediaSsrcMap();
var newMedia = {};
Object.keys(othersMedias).forEach(function(othersMediaIdx) {
var myMedia = myMedias[othersMediaIdx];
var othersMedia = othersMedias[othersMediaIdx];
if(!myMedia && othersMedia) {
// Add whole channel
newMedia[othersMediaIdx] = othersMedia;
return;
}
// Look for new ssrcs accross the channel
Object.keys(othersMedia.ssrcs).forEach(function(ssrc) {
if(Object.keys(myMedia.ssrcs).indexOf(ssrc) === -1) {
// Allocate channel if we've found ssrc that doesn't exist in our channel
if(!newMedia[othersMediaIdx]){
newMedia[othersMediaIdx] = {
mediaindex: othersMedia.mediaindex,
mid: othersMedia.mid,
ssrcs: {},
ssrcGroups: []
};
}
newMedia[othersMediaIdx].ssrcs[ssrc] = othersMedia.ssrcs[ssrc];
}
});
// Look for new ssrc groups across the channels
othersMedia.ssrcGroups.forEach(function(otherSsrcGroup){
// try to match the other ssrc-group with an ssrc-group of ours
var matched = false;
for (var i = 0; i < myMedia.ssrcGroups.length; i++) {
var mySsrcGroup = myMedia.ssrcGroups[i];
if (otherSsrcGroup.semantics == mySsrcGroup.semantics
&& arrayEquals.apply(otherSsrcGroup.ssrcs, [mySsrcGroup.ssrcs])) {
matched = true;
break;
}
}
if (!matched) {
// Allocate channel if we've found an ssrc-group that doesn't
// exist in our channel
if(!newMedia[othersMediaIdx]){
newMedia[othersMediaIdx] = {
mediaindex: othersMedia.mediaindex,
mid: othersMedia.mid,
ssrcs: {},
ssrcGroups: []
};
}
newMedia[othersMediaIdx].ssrcGroups.push(otherSsrcGroup);
}
});
});
return newMedia;
};
/**
* Sends SSRC update IQ.
* @param sdpMediaSsrcs SSRCs map obtained from SDP.getNewMedia. Cntains SSRCs to add/remove.
* @param sid session identifier that will be put into the IQ.
* @param initiator initiator identifier.
* @param toJid destination Jid
* @param isAdd indicates if this is remove or add operation.
*/
SDPDiffer.prototype.toJingle = function(modify) {
var sdpMediaSsrcs = this.getNewMedia();
var self = this;
// FIXME: only announce video ssrcs since we mix audio and dont need
// the audio ssrcs therefore
var modified = false;
Object.keys(sdpMediaSsrcs).forEach(function(mediaindex){
modified = true;
var media = sdpMediaSsrcs[mediaindex];
modify.c('content', {name: media.mid});
modify.c('description', {xmlns:'urn:xmpp:jingle:apps:rtp:1', media: media.mid});
// FIXME: not completly sure this operates on blocks and / or handles different ssrcs correctly
// generate sources from lines
Object.keys(media.ssrcs).forEach(function(ssrcNum) {
var mediaSsrc = media.ssrcs[ssrcNum];
modify.c('source', { xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
modify.attrs({ssrc: mediaSsrc.ssrc});
// iterate over ssrc lines
mediaSsrc.lines.forEach(function (line) {
var idx = line.indexOf(' ');
var kv = line.substr(idx + 1);
modify.c('parameter');
if (kv.indexOf(':') == -1) {
modify.attrs({ name: kv });
} else {
modify.attrs({ name: kv.split(':', 2)[0] });
modify.attrs({ value: kv.split(':', 2)[1] });
}
modify.up(); // end of parameter
});
modify.up(); // end of source
});
// generate source groups from lines
media.ssrcGroups.forEach(function(ssrcGroup) {
if (ssrcGroup.ssrcs.length != 0) {
modify.c('ssrc-group', {
semantics: ssrcGroup.semantics,
xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0'
});
ssrcGroup.ssrcs.forEach(function (ssrc) {
modify.c('source', { ssrc: ssrc })
.up(); // end of source
});
modify.up(); // end of ssrc-group
}
});
modify.up(); // end of description
modify.up(); // end of content
});
return modified;
};
module.exports = SDPDiffer;