From be942fd66a8f1f9510bca66a3049fce2cb0392b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=A0imon=20Brandner?= <simon.bra.ag@gmail.com>
Date: Wed, 15 Sep 2021 16:38:59 +0200
Subject: [PATCH] Remove RTX codec hack as the issue is no longer present on
 Chromium 90
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Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>
---
 src/webrtc/call.ts | 44 --------------------------------------------
 1 file changed, 44 deletions(-)

diff --git a/src/webrtc/call.ts b/src/webrtc/call.ts
index 79df07b43..5767b96c5 100644
--- a/src/webrtc/call.ts
+++ b/src/webrtc/call.ts
@@ -1068,7 +1068,6 @@ export class MatrixCall extends EventEmitter {
 
         let myAnswer;
         try {
-            this.getRidOfRTXCodecs();
             myAnswer = await this.peerConn.createAnswer();
         } catch (err) {
             logger.debug("Failed to create answer: ", err);
@@ -1285,7 +1284,6 @@ export class MatrixCall extends EventEmitter {
             await this.peerConn.setRemoteDescription(description);
 
             if (description.type === 'offer') {
-                this.getRidOfRTXCodecs();
                 const localDescription = await this.peerConn.createAnswer();
                 await this.peerConn.setLocalDescription(localDescription);
 
@@ -1499,47 +1497,6 @@ export class MatrixCall extends EventEmitter {
         stream.addEventListener("removetrack", () => this.deleteFeedByStream(stream));
     };
 
-    /**
-     * This method removes all video/rtx codecs from screensharing video
-     * transceivers. This is necessary since they can cause problems. Without
-     * this the following steps should produce an error:
-     *   Chromium calls Firefox
-     *   Firefox answers
-     *   Firefox starts screen-sharing
-     *   Chromium starts screen-sharing
-     *   Call crashes for Chromium with:
-     *       [96685:23:0518/162603.933321:ERROR:webrtc_video_engine.cc(3296)] RTX codec (PT=97) mapped to PT=96 which is not in the codec list.
-     *       [96685:23:0518/162603.933377:ERROR:webrtc_video_engine.cc(1171)] GetChangedRecvParameters called without any video codecs.
-     *       [96685:23:0518/162603.933430:ERROR:sdp_offer_answer.cc(4302)] Failed to set local video description recv parameters for m-section with mid='2'. (INVALID_PARAMETER)
-     */
-    private getRidOfRTXCodecs(): void {
-        // RTCRtpReceiver.getCapabilities and RTCRtpSender.getCapabilities don't seem to be supported on FF
-        if (!RTCRtpReceiver.getCapabilities || !RTCRtpSender.getCapabilities) return;
-
-        const recvCodecs = RTCRtpReceiver.getCapabilities("video").codecs;
-        const sendCodecs = RTCRtpSender.getCapabilities("video").codecs;
-        const codecs = [...sendCodecs, ...recvCodecs];
-
-        for (const codec of codecs) {
-            if (codec.mimeType === "video/rtx") {
-                const rtxCodecIndex = codecs.indexOf(codec);
-                codecs.splice(rtxCodecIndex, 1);
-            }
-        }
-
-        for (const trans of this.peerConn.getTransceivers()) {
-            if (
-                this.screensharingSenders.includes(trans.sender) &&
-                    (
-                        trans.sender.track?.kind === "video" ||
-                        trans.receiver.track?.kind === "video"
-                    )
-            ) {
-                trans.setCodecPreferences(codecs);
-            }
-        }
-    }
-
     private onNegotiationNeeded = async (): Promise<void> => {
         logger.info("Negotiation is needed!");
 
@@ -1550,7 +1507,6 @@ export class MatrixCall extends EventEmitter {
 
         this.makingOffer = true;
         try {
-            this.getRidOfRTXCodecs();
             const myOffer = await this.peerConn.createOffer();
             await this.gotLocalOffer(myOffer);
         } catch (e) {