From 165fd50861deefc5b7df9de71e4567151e894295 Mon Sep 17 00:00:00 2001
From: Philipp Hancke <phancke@microsoft.com>
Date: Wed, 29 Nov 2023 10:11:22 +0100
Subject: [PATCH] e2ee: move setCodecPreferences out of videopipe

---
 .../endtoend-encryption/js/main.js            | 29 +++++++++++++++++
 .../endtoend-encryption/js/videopipe.js       | 31 +------------------
 2 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/src/content/insertable-streams/endtoend-encryption/js/main.js b/src/content/insertable-streams/endtoend-encryption/js/main.js
index 304ced712f..b4b20c9f2d 100644
--- a/src/content/insertable-streams/endtoend-encryption/js/main.js
+++ b/src/content/insertable-streams/endtoend-encryption/js/main.js
@@ -39,6 +39,14 @@ let localStream;
 // eslint-disable-next-line no-unused-vars
 let remoteStream;
 
+// Preferring a certain codec is an expert option without GUI.
+// Use opus by default.
+// eslint-disable-next-line prefer-const
+let preferredAudioCodecMimeType = 'audio/opus';
+// Use VP8 by default to limit depacketization issues.
+// eslint-disable-next-line prefer-const
+let preferredVideoCodecMimeType = 'video/VP8';
+
 let hasEnoughAPIs = !!window.RTCRtpScriptTransform;
 
 if (!hasEnoughAPIs) {
@@ -141,6 +149,25 @@ function setupReceiverTransform(receiver) {
   }, [readable, writable]);
 }
 
+function maybeSetCodecPreferences(trackEvent) {
+  if (!'setCodecPreferences' in window.RTCRtpTransceiver.prototype) return;
+  if (trackEvent.track.kind === 'audio' && preferredAudioCodecMimeType ) {
+    const {codecs} = RTCRtpReceiver.getCapabilities('audio');
+    const selectedCodecIndex = codecs.findIndex(c => c.mimeType === preferredAudioCodecMimeType);
+    const selectedCodec = codecs[selectedCodecIndex];
+    codecs.splice(selectedCodecIndex, 1);
+    codecs.unshift(selectedCodec);
+    trackEvent.transceiver.setCodecPreferences(codecs);
+  } else if (trackEvent.track.kind === 'video' && preferredVideoCodecMimeType) {
+    const {codecs} = RTCRtpReceiver.getCapabilities('video');
+    const selectedCodecIndex = codecs.findIndex(c => c.mimeType === preferredVideoCodecMimeType);
+    const selectedCodec = codecs[selectedCodecIndex];
+    codecs.splice(selectedCodecIndex, 1);
+    codecs.unshift(selectedCodec);
+    trackEvent.transceiver.setCodecPreferences(codecs);
+  }
+}
+
 function call() {
   callButton.disabled = true;
   hangupButton.disabled = false;
@@ -151,6 +178,7 @@ function call() {
   // to both places.
   startToMiddle = new VideoPipe(localStream, true, false, e => {
     // Do not setup the receiver transform.
+    maybeSetCodecPreferences(e);
     videoMonitor.srcObject = e.streams[0];
   });
   startToMiddle.pc1.getSenders().forEach(setupSenderTransform);
@@ -158,6 +186,7 @@ function call() {
 
   startToEnd = new VideoPipe(localStream, true, true, e => {
     setupReceiverTransform(e.receiver);
+    maybeSetCodecPreferences(e);
     gotRemoteStream(e.streams[0]);
   });
   startToEnd.pc1.getSenders().forEach(setupSenderTransform);
diff --git a/src/content/insertable-streams/endtoend-encryption/js/videopipe.js b/src/content/insertable-streams/endtoend-encryption/js/videopipe.js
index 30e768da75..353fcd0ee7 100644
--- a/src/content/insertable-streams/endtoend-encryption/js/videopipe.js
+++ b/src/content/insertable-streams/endtoend-encryption/js/videopipe.js
@@ -21,14 +21,6 @@
 //
 'use strict';
 
-// Preferring a certain codec is an expert option without GUI.
-// Use opus by default.
-// eslint-disable-next-line prefer-const
-let preferredAudioCodecMimeType = 'audio/opus';
-// Use VP8 by default to limit depacketization issues.
-// eslint-disable-next-line prefer-const
-let preferredVideoCodecMimeType = 'video/VP8';
-
 function VideoPipe(stream, forceSend, forceReceive, handler) {
   this.pc1 = new RTCPeerConnection({
     encodedInsertableStreams: forceSend,
@@ -36,28 +28,7 @@ function VideoPipe(stream, forceSend, forceReceive, handler) {
   this.pc2 = new RTCPeerConnection({
     encodedInsertableStreams: forceReceive,
   });
-  if ('setCodecPreferences' in window.RTCRtpTransceiver.prototype) {
-    this.pc2.ontrack = (e) => {
-      if (e.track.kind === 'audio' && preferredAudioCodecMimeType ) {
-        const {codecs} = RTCRtpReceiver.getCapabilities('audio');
-        const selectedCodecIndex = codecs.findIndex(c => c.mimeType === preferredAudioCodecMimeType);
-        const selectedCodec = codecs[selectedCodecIndex];
-        codecs.splice(selectedCodecIndex, 1);
-        codecs.unshift(selectedCodec);
-        e.transceiver.setCodecPreferences(codecs);
-      } else if (e.track.kind === 'video' && preferredVideoCodecMimeType) {
-        const {codecs} = RTCRtpReceiver.getCapabilities('video');
-        const selectedCodecIndex = codecs.findIndex(c => c.mimeType === preferredVideoCodecMimeType);
-        const selectedCodec = codecs[selectedCodecIndex];
-        codecs.splice(selectedCodecIndex, 1);
-        codecs.unshift(selectedCodec);
-        e.transceiver.setCodecPreferences(codecs);
-      }
-      handler(e);
-    };
-  } else {
-    this.pc2.ontrack = handler;
-  }
+  this.pc2.ontrack = handler;
   stream.getTracks().forEach((track) => this.pc1.addTrack(track, stream));
 }