Compare sdp to determine if transcoding is being used. (#1444)

* compare sdp for transcoding

* refactor sdp check for leading codec

* fix reference to epOther

* minor changes

* minor

* fix #1447

* fix security issue

* use convenience getter appIsUsingWebsockets in CallSession

---------

Co-authored-by: Dave Horton <daveh@beachdognet.com>

lib/session/call-session.js

@@ -951,10 +951,12 @@ class CallSession extends Emitter {
   }
 
   stopTtsStream() {
+    if (this.appIsUsingWebsockets) {
       this.requestor?.request('tts:streaming-event', '/streaming-event', {event_type: 'stream_closed'})
         .catch((err) => this.logger.info({err}, 'CallSession:clearTtsStream - Error sending user_interruption'));
       this.ttsStreamingBuffer?.stop();
     }
+  }
 
   async enableBotMode(gather, autoEnable) {
     try {
@@ -979,7 +981,7 @@ class CallSession extends Emitter {
       task.sticky = autoEnable;
       // listen to the bargein-done from background manager
       this.backgroundTaskManager.on('bargeIn-done', () => {
-        if (this.requestor instanceof WsRequestor) {
+        if (this.appIsUsingWebsockets) {
           try {
             this.kill(true);
           } catch (err) {}
@@ -1337,7 +1339,7 @@ class CallSession extends Emitter {
       }
 
       if (0 === this.tasks.length &&
-        this.requestor instanceof WsRequestor &&
+        this.appIsUsingWebsockets &&
         !this.requestor.closedGracefully &&
         !this.callGone &&
         !this.isConfirmCallSession
@@ -3023,14 +3025,14 @@ Duration=${duration} `
    */
 
   _notifyTaskError(obj) {
-    if (this.requestor instanceof WsRequestor) {
+    if (this.appIsUsingWebsockets) {
       this.requestor.request('jambonz:error', '/error', obj)
         .catch((err) => this.logger.debug({err}, 'CallSession:_notifyTaskError - Error sending'));
     }
   }
 
   _notifyTaskStatus(task, evt) {
-    if (this.notifyEvents && this.requestor instanceof WsRequestor) {
+    if (this.notifyEvents && this.appIsUsingWebsockets) {
       const obj = {...evt, id: task.id, name: task.name};
       this.requestor.request('verb:status', '/status', obj)
         .catch((err) => this.logger.debug({err}, 'CallSession:_notifyTaskStatus - Error sending'));
@@ -3082,7 +3084,7 @@ Duration=${duration} `
   }
 
   _clearTasks(backgroundGather, evt) {
-    if (this.requestor instanceof WsRequestor && !backgroundGather.cleared) {
+    if (this.appIsUsingWebsockets && !backgroundGather.cleared) {
       this.logger.debug({evt}, 'CallSession:_clearTasks on event from background gather');
       try {
         backgroundGather.cleared = true;

lib/tasks/dial.js

@@ -21,7 +21,7 @@ const {parseUri} = require('drachtio-srf');
 const {ANCHOR_MEDIA_ALWAYS,
   JAMBONZ_DIAL_PAI_HEADER,
   JAMBONES_DIAL_SBC_FOR_REGISTERED_USER} = require('../config');
-const { isOnhold, isOpusFirst } = require('../utils/sdp-utils');
+const { isOnhold, isOpusFirst, getLeadingCodec } = require('../utils/sdp-utils');
 const { normalizeJambones } = require('@jambonz/verb-specifications');
 const { selectHostPort } = require('../utils/network');
 const { sleepFor } = require('../utils/helpers');
@@ -158,6 +158,7 @@ class TaskDial extends Task {
 
   get canReleaseMedia() {
     const keepAnchor = this.data.anchorMedia ||
+      this.weAreTranscoding ||
       this.cs.isBackGroundListen ||
       this.cs.onHoldMusic ||
       ANCHOR_MEDIA_ALWAYS ||
@@ -929,7 +930,13 @@ class TaskDial extends Task {
         this.logger.info({err}, 'Dial:_selectSingleDial - Error boosting audio signal');
       }
     }
-
+    /* basic determination to see if call is being transcoded */
+    const codecA = getLeadingCodec(this.epOther.local.sdp);
+    const codecB = getLeadingCodec(this.ep.remote.sdp);
+    this.weAreTranscoding = (codecA !== codecB);
+    if (this.weAreTranscoding) {
+      this.logger.info(`Dial:_selectSingleDial - transcoding from ${codecA} (A leg) to ${codecB} (B leg)`);
+    }
     /* if we can release the media back to the SBC, do so now */
     if (this.canReleaseMedia || this.shouldExitMediaPathEntirely) {
       setTimeout(this._releaseMedia.bind(this, cs, sd, this.shouldExitMediaPathEntirely), 200);

lib/utils/sdp-utils.js

@@ -55,11 +55,28 @@ const extractSdpMedia = (sdp) => {
   }
 };
 
+const getLeadingCodec = (sdp) => {
+  if (!sdp) {
+    return null;
+  }
+
+  const parsed = sdpTransform.parse(sdp);
+  const audio = parsed.media?.find((m) => m.type === 'audio');
+
+  if (!audio) {
+    return null;
+  }
+
+  return audio.rtp?.[0]?.codec || null;
+};
+
+
 module.exports = {
   isOnhold,
   mergeSdpMedia,
   extractSdpMedia,
   isOpusFirst,
   makeOpusFirst,
-  removeVideoSdp
+  removeVideoSdp,
+  getLeadingCodec
 };

package-lock.json

@@ -6183,9 +6183,10 @@
       "license": "MIT"
     },
     "node_modules/js-yaml": {
-      "version": "3.14.1",
+      "version": "3.14.2",
+      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.2.tgz",
+      "integrity": "sha512-PMSmkqxr106Xa156c2M265Z+FTrPl+oxd/rgOQy2tijQeK5TxQ43psO1ZCwhVOSdnn+RzkzlRz/eY4BgJBYVpg==",
       "dev": true,
-      "license": "MIT",
       "dependencies": {
         "argparse": "^1.0.7",
         "esprima": "^4.0.0"