在webrtc上为iOS启用立体声

我在iOS上使用Opus编解码器进行webrtc音频流(libjingle_peerconnection).如何为音频播放启用立体声？

我在这篇博文中借用了一些想法,希望我可以让它发挥作用.我们能够为我们的Web客户端启用立体声,而不是我们的iOS客户端.

https://www.webrtcexample.com/blog/?go=all/how-to-support-stereo-in-a-webrtc-application/

我在提供和对等连接约束的约束中禁用回声消除,如下所示：

private func initializeConsTraints() -> RTCMediaConsTraints {
    let mandatoryConsTraints = [
        RTCPair(key: "OfferToReceiveAudio",value: "true"),RTCPair(key: "OfferToReceiveVideo",value: "false"),RTCPair(key: "echoCancellation",RTCPair(key: "googEchoCancellation",value: "false")
    ]
    let optionalConsTraints = [
        RTCPair(key: "internalSctPDAtaChAnnels",RTCPair(key: "DtlsSrtpKeyAgreement",value: "true")
    ]
    return RTCMediaConsTraints(mandatoryConsTraints: mandatoryConsTraints,optionalConsTraints: optionalConsTraints)
}

我正在为Opus音频编解码器启用立体声,如下所示：

func peerConnection(peerConnection: RTCPeerConnection!,didCreateSessionDescription sdp: RTCSessionDescription!,error: NSError?) {
    LOGD("created sdp")

    guard error == nil else {
        LOGE("error creaTing session description: \(error!)")
        delegate.onError(self,description: "Error creaTing sdp")
        return
    }

    dispatch_async(dispatch_get_main_queue()) {
        let replaCEThis = "fmtp:111 minptime=10; useinbandfec=1"
        let replaceWith = "fmtp:111 minptime=10; useinbandfec=1; stereo=1; sprop-stereo=1"
        let sdpDescriptionWithStereo = sdp.description.StringByreplacingoccurrencesOfString(replaCEThis,withString: replaceWith)
        let sdpWithStereo = RTCSessionDescription(type: sdp.type,sdp: sdpDescriptionWithStereo)
        peerConnection.setLocalDescriptionWithDelegate(self,sessionDescription: sdpWithStereo)

        self.delegate.onLocalSDP(self,type: sdp.type,sdp: sdpDescriptionWithStereo)
    }
}

我在sdpDescriptionWithStereo中获得了所需的结果.但我仍然无法获得立体声音效.

(而且,是的,我知道StringByreplacingoccurrencesOfString是一个彻头彻尾的黑客,但我稍后会谈到)

NotificationCenter.default.addObserver(self,SELEctor: #SELEctor(JanusCommunicationManager.didSessionRouteChangE),name: Nsnotification.Name.AVAudioSessionRouteChange,object: nil)

     @objc func didSessionRouteChange(notification:Notification) {
        let Dict = notification.userInfo
        let routeChangeReason = Dict![AVAudioSessionRouteChangeReasonKey] as! UInt
        let error:Error? = nil
        switch routeChangeReason {
        case AVAudioSessionRouteChangeReason.categoryChange.rawValue:
            try? AVAudioSession.sharedInstance().overrideOutputAudioPort(.nonE)
            break
        default:
            break
        }

    }