Ensure mid is always interpreted as string (#1641)

Author: lukasIO

.changeset/olive-mayflies-accept.md

@@ -0,0 +1,5 @@
+---
+"livekit-client": patch
+---
+
+Ensure mid is always interpreted as string

package.json

@@ -83,7 +83,7 @@
     "@size-limit/webpack": "^11.2.0",
     "@trivago/prettier-plugin-sort-imports": "^5.0.0",
     "@types/events": "^3.0.3",
-    "@types/sdp-transform": "2.4.10",
+    "@types/sdp-transform": "2.15.0",
     "@types/ua-parser-js": "0.7.39",
     "@typescript-eslint/eslint-plugin": "7.18.0",
     "@typescript-eslint/parser": "7.18.0",

pnpm-lock.yaml

@@ -165,10 +165,11 @@ export default class PCTransport extends EventEmitter {
     } else if (sd.type === 'answer') {
       const sdpParsed = parse(sd.sdp ?? '');
       sdpParsed.media.forEach((media) => {
+        const mid = getMidString(media.mid!);
         if (media.type === 'audio') {
           // mung sdp for opus bitrate settings
           this.trackBitrates.some((trackbr): boolean => {
-            if (!trackbr.transceiver || media.mid != trackbr.transceiver.mid) {
+            if (!trackbr.transceiver || mid != trackbr.transceiver.mid) {
               return false;
             }
 
@@ -593,6 +594,9 @@ function ensureAudioNackAndStereo(
   stereoMids: string[],
   nackMids: string[],
 ) {
+  // sdp-transform types don't include number however the parser outputs mids as numbers in some cases
+  const mid = getMidString(media.mid!);
+
   // found opus codec to add nack fb
   let opusPayload = 0;
   media.rtp.some((rtp): boolean => {
@@ -610,7 +614,7 @@ function ensureAudioNackAndStereo(
     }
 
     if (
-      nackMids.includes(media.mid!) &&
+      nackMids.includes(mid) &&
       !media.rtcpFb.some((fb) => fb.payload === opusPayload && fb.type === 'nack')
     ) {
       media.rtcpFb.push({
@@ -619,7 +623,7 @@ function ensureAudioNackAndStereo(
       });
     }
 
-    if (stereoMids.includes(media.mid!)) {
+    if (stereoMids.includes(mid)) {
       media.fmtp.some((fmtp): boolean => {
         if (fmtp.payload === opusPayload) {
           if (!fmtp.config.includes('stereo=1')) {
@@ -642,6 +646,7 @@ function extractStereoAndNackAudioFromOffer(offer: RTCSessionDescriptionInit): {
   const sdpParsed = parse(offer.sdp ?? '');
   let opusPayload = 0;
   sdpParsed.media.forEach((media) => {
+    const mid = getMidString(media.mid!);
     if (media.type === 'audio') {
       media.rtp.some((rtp): boolean => {
         if (rtp.codec === 'opus') {
@@ -652,13 +657,13 @@ function extractStereoAndNackAudioFromOffer(offer: RTCSessionDescriptionInit): {
       });
 
       if (media.rtcpFb?.some((fb) => fb.payload === opusPayload && fb.type === 'nack')) {
-        nackMids.push(media.mid!);
+        nackMids.push(mid);
       }
 
       media.fmtp.some((fmtp): boolean => {
         if (fmtp.payload === opusPayload) {
           if (fmtp.config.includes('sprop-stereo=1')) {
-            stereoMids.push(media.mid!);
+            stereoMids.push(mid);
           }
           return true;
         }
@@ -682,3 +687,7 @@ function ensureIPAddrMatchVersion(media: MediaDescription) {
     }
   }
 }
+
+function getMidString(mid: string | number) {
+  return typeof mid === 'number' ? mid.toFixed(0) : mid;
+}