VideoCodecFix.js

var prioritizeVideoCodecs;
var prioritizeAudioCodecs;

//On peer Connection
this.pc.on('offer', function (offer) {
   offer = prioritizeVideoCodecs(offer);
   offer = prioritizeAudioCodecs(offer);
   if (self.parent.config.nick) offer.nick = self.parent.config.nick;
   self.send('offer', offer);
});

prioritizeVideoCodecs = function(payload) {
   var priority =  ["VP9","VP8","H.264","H.264"];  // ordered priority list, first = highest priority
   var ids = [];
   Object.keys(priority).forEach(function (key) {
       var id = findCodecId(payload, priority[key]);
       if (id) {
           ids.push(id);
       }
   });
   if (ids.length > 0 && payload && payload.sdp) {
       var sdp = payload.sdp;
       var m = sdp.match(/m=video\s(\d+)\s[A-Z\/]+\s([0-9\ ]+)/);
       if (m !== null && m.length === 3) {
           var candidates = m[2].split(" ");
           var prioritized = ids;
           Object.keys(candidates).forEach(function (key) {
               if (ids.indexOf(candidates[key]) === -1) {
                   //prioritized.push(121);
                   prioritized.push(candidates[key]);
               }
           });
           var mPrioritized = m[0].replace(m[2], prioritized.join(" "));
         //  logger.info("Setting video codec priority. \"%s\"", mPrioritized);
           payload.sdp = sdp.replace(m[0], mPrioritized);


       }
   }
   return payload;
};

prioritizeAudioCodecs = function(payload) {
  // logger.info(payload);
   // ,"telephone-event" "opus"
   var priority = ["iLBC","PCMU","opus","telephone-event"];
   var ids = [];
   Object.keys(priority).forEach(function (key) {
       var id = findCodecId(payload, priority[key]);
       if (id) {
           ids.push(id);
       }
   });
   if (ids.length > 0 && payload && payload.sdp) {
       var sdp = payload.sdp;
       var m = sdp.match(/m=audio\s(\d+)\s[A-Z\/]+\s([0-9\ ]+)/);
       if (m !== null && m.length === 3) {
           var candidates = m[2].split(" ");
           var prioritized = ids;
           Object.keys(candidates).forEach(function (key) {
               if (ids.indexOf(candidates[key]) === -1) {
                   //prioritized.push(121);
                   prioritized.push(candidates[key]);
               }
           });
           var mPrioritized = m[0].replace(m[2], prioritized.join(" "));
       //    logger.info("audio codec Details: . \"%s\"", mPrioritized);
           //When Need To Modifiy Priority
           payload.sdp = sdp.replace(m[0], mPrioritized);
       }
   }
 /*  var maxAvgBitRate = config.maxAverageBitRate || 0;
   if (maxAvgBitRate > 0) {
       var id = findCodecId(details, "opus");
       if (id && details.payload && details.payload.sdp) {
           details.payload.sdp = alterFmtpConfig(details.payload.sdp, id, {"maxaveragebitrate": maxAvgBitRate});
       }
   }*/
   return payload;
};

function findCodecId(details, codec) {
   if (details.payload && details.payload.sdp) {
       var pattern = "a=rtpmap\\:(\\d+)\\s" + codec + "\\/\\d+";
       var re = new RegExp(pattern);
       var m = details.payload.sdp.match(re);
       if (m !== null && m.length > 0) {
           return m[1];
       }
   }
   return null;
}