Implement RTCPeerConnection.addTransceiver

[hthetiot]

Versions affected

• Cordova version (e.g 7.1.0): N/A
• Cordova iOS version (e.g 5.1.0): N/A
• Plugin version (e.g 6.0.12): 6.0.14
• iOS version (e.g 10.2): N/A
• Xcode version (e.g 11.1 - 11A1027): N/A
• WebRTC-adapter version (e.g. 7.4.0): N/A
• WebRTC Framework version (e.g. JSSip 3.1.2): N/A

Description

Currently iosRTC DOES NOT support addTransceiver.

Expected results

Be able to use addTransceiver.

Actual results

addTransceiver is not a fonction.

References:

• https://chromium.googlesource.com/chromium/src.git/+/5ccc9382e7bd5c7dac9349fc1aae6fdc66a6ff4c%5E%21/#F7
• https://www.chromestatus.com/feature/5700232381726720

[hthetiot]

Related: https://github.com/react-native-webrtc/react-native-webrtc/pull/773/files

[hthetiot]

Related: w3c/webrtc-pc#2024

[hthetiot]

Related

cordova-plugin-iosrtc/lib/WebRTC.framework/Headers/RTCPeerConnection.h

Line 118 in cdfe684

- (void)peerConnection:(RTCPeerConnection *)peerConnection

See didStartReceivingOnTransceiver:(RTCRtpTransceiver and use of RTCRtpTransceiver that need to be implemented in PluginRTCConnection

[dgreif]

@hthetiot thanks for all the reference material. I'm planning to start diving into this today.

[hthetiot]

'peerConnection(:didStartReceivingOnTransceiver:)' has been renamed to 'peerConnection(:didStartReceivingOn:)'
Replace 'didStartReceivingOnTransceiver' with 'didStartReceivingOn'

'peerConnection(:didAddReceiver:streams:)' has been renamed to 'peerConnection(:didAdd:streams:)'
Replace 'didAddReceiver' with 'didAdd'

[hthetiot]

func peerConnection(_ peerConnection: RTCPeerConnection, didStartReceivingOn rtpTransceiver: RTCRtpTransceiver) {
        
        NSLog("PluginRTCPeerConnection | didStartReceivingOn rtpTransceiver")
 }

[hthetiot]

Other RTCPeerConnection property and methods that you can use are:

/** Gets all RTCRtpTransceivers associated with this peer connection.
 *  Note: reading this property returns different instances of
 *  RTCRtpTransceiver. Use isEqual: instead of == to compare RTCRtpTransceiver
 *  instances.
 *  This is only available with RTCSdpSemanticsUnifiedPlan specified.
 */
@property(nonatomic, readonly) NSArray<RTCRtpTransceiver *> *transceivers;

/** Adds a transceiver with a sender set to transmit the given track. The kind
 *  of the transceiver (and sender/receiver) will be derived from the kind of
 *  the track.
 */
- (RTCRtpTransceiver *)addTransceiverWithTrack:(RTCMediaStreamTrack *)track;
- (RTCRtpTransceiver *)addTransceiverWithTrack:(RTCMediaStreamTrack *)track
                                          init:(RTCRtpTransceiverInit *)init;

/** Adds a transceiver with the given kind. Can either be RTCRtpMediaTypeAudio
 *  or RTCRtpMediaTypeVideo.
 */
- (RTCRtpTransceiver *)addTransceiverOfType:(RTCRtpMediaType)mediaType;
- (RTCRtpTransceiver *)addTransceiverOfType:(RTCRtpMediaType)mediaType
                                       init:(RTCRtpTransceiverInit *)init;

[dgreif]

Thanks for the additional info @hthetiot. I started diving into the code for this yesterday, wrapping my head around all the changes needed. Should make some good progress today.

[dgreif]

@hthetiot sorry for the delay, I took a day off and then had to rework this a couple times to get it as close to spec as possible. I'm very close, but hit an issue when compiling that I can't find a fix for. I'm guessing it's related to the webrtc header files (maybe related to missing RTC_EXPORT on RTCRtpTransceiverInit), but I don't use swift enough to know what might be causing this:

This shows up if I try to cast to the RTCRtpTransceiverInit interface, which I need to do when casting my command arguments in iosrtcPlugin.swift and in addTransceiver in PluginRTCPeerConnection.swift. Any idea what might be causing that interface to not be accessible when compiling?

[hthetiot]

@hthetiot sorry for the delay, I took a day off and then had to rework this a couple times to get it as close to spec as possible.

No need to apologise, take all the time you need.

Regarding RTCRtpTransceiverInit not sure I can help without running the PR myself feel free to push a PR with Work in progress.

Another point I want to raise is you may check that task/8.0.0 branch since it contains a more recent version of WebRTC.

[dgreif]

The 8.0.0 header file for transceivers does include the RTC_OBJC_EXPORT annotation for RTCRtpTransceiverInit, so hopefully that means it's properly set up for use.

If you want to try debugging it a little in v6, you can add this line to any of the bridge methods in iosrtcPlugin.swift:

let fakeInit = command.argument(at: 5) as! RTCRtpTransceiverInit

Even if you don't use fakeInit, the cast is enough to get the compiler to look for the class and fail the build. Let me know if you find anything this weekend. Otherwise, I'll definitely try rebasing on the 8.0.0 branch Monday