RTCPeerConnection.addTrack() causes app to crash when a stream is provided as input param and Unified Plan is used

[esrauenal]

Hi All,

We ran into a very strange problem that we have not been able to figure out yet. I hope you can help us. We have WebRTC based clients for iOS and Android developed with Cordova and we are working on moving from a WebRTC Plan B implementation to Unified Plan.
When we test Unified Plan mode on Android, basic calls work fine. However, when we initiate an audio call on iOS, the app crashes immediately. This is the errors we get before crash:

Fatal error in: ../../pc/peer_connection.cc, line 1400
last system error: 0
Check failed: !IsUnifiedPlan()
AddStream is not available with Unified Plan SdpSemantics. Please use AddTrack instead.2021-05-25 10:47:40.560756+0300 OmniMobile[2378:1114401] iosrtcPlugin#RTCPeerConnection_createOffer(

This error seems to be printed in Chromium: https://chromium.googlesource.com/external/webrtc/+/d7180cccc48efdec6241e3b21449046e62ebb91a/pc/peer_connection.cc#1155

As suggested here: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/addStream, we stopped using RTCPeerConnection.addStream() and migrated to RTCPeerConnection.addTrack() when moving to Unified Plan implementation. So, RTCPeerConnection.addStream() is not being called by our client.

Looking into the plugin code (https://github.com/cordova-rtc/cordova-plugin-iosrtc/blob/6.0.13/dist/cordova-plugin-iosrtc.js#L2272), we saw that RTCPeerConnection.addStream() is called by the RTCPeerConnection.addTrack() function when a stream is provided as a second input parameter. After commenting out this line, the app did not crash but speech path was missing on both sides. To overcome this, we replaced the RTCPeerConnection.addStream() code withRTCPeerConnection.addTrack() as suggested here: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/addStream#migrating_to_addtrack(). This resolved the speech path issue and prevented the app form crashing.
However, we don't know if this is an issue that only we are having and if our workaround is correct.

Also, we have considered upgrading the plugin but since the latest implementation of RTCPeerConnection.addTrack() is similar (https://github.com/cordova-rtc/cordova-plugin-iosrtc/blob/master/www/cordova-plugin-iosrtc.js#L2403) we did not expect an improvement there.

Any help or suggestions you can provide will be greatly appreciated :)

Cordova version: 7.1.0
Cordova iOS version: 5.1.1
Plugin version: 6.0.13
iOS version: 14.4.1
Xcode version: 12.3 (12C33)
WebRTC Framework version: WebRTC M85 based private build

[hthetiot]

Plugin version: 6.0.13

Try Plugin version: 6.0.21 you going to need it to receive call from Chrome 89+ anyway see #666

[hthetiot]

you cannot use 6.0.13 with WebRTC M85 you need master for that, it ready for 89.

[hthetiot]

Version 6+ only support WebRTC M69 max, to use M80+ you need master aka version 8+ #687

[esrauenal]

Many thanks! I will try with latest code on master.

[hthetiot]

Great keep me posted and feel free to confirm master by leaving a comment here #687

[hthetiot]

Did it fix your issue using master?