使用WebRTC实现语音通话，视频通话

摘要: 语音通话，视频通话，WebRTC

WebRTC介绍

WebRTC，名称源自网页实时通信（Web Real-Time Communication）的缩写，是一个支持网页浏览器进行实时语音对话或视频对话的技术，谷歌2011年5月进行开源。

WebRTC提供了视频会议的核心技术，包括音视频的采集、编解码、网络传输、显示等功能，并且还支持跨平台：windows，linux，mac，android。

1.通过CocoaPods依赖WebRTC

pod 'libjingle_peerconnection'

2.搭建RTC服务器用于信灵交互，可以使用github上开源代码https://github.com/LingyuCoder/SkyRTC

3.引入WebRTC的头文件

#import "RTCICEServer.h"
#import "RTCICECandidate.h"
#import "RTCICEServer.h"
#import "RTCMediaConstraints.h"
#import "RTCMediaStream.h"
#import "RTCPair.h"
#import "RTCPeerConnection.h"
#import "RTCPeerConnectionDelegate.h"
#import "RTCPeerConnectionFactory.h"
#import "RTCSessionDescription.h"
#import "RTCVideoRenderer.h"
#import "RTCVideoCapturer.h"
#import "RTCVideoTrack.h"
#import "RTCAudioTrack.h"
#import "RTCSessionDescriptionDelegate.h"
#import "RTCEAGLVideoView.h"
#import <AVFoundation/AVFoundation.h>

4.引入必要的依赖库

AudioToolbox.framework
VideoToolbox.framework
QuartzCore.framework
OpenGLES.framework
CoreGraphics.framework
CoreVideo.framework
CoreMedia.framework
CoreAudio.framework
AVFoundation.framework
GLKit.framework
CFNetwork.framework
Security.framework
libsqlite3.tbd
libicucore.tbd
libc.tbd
libstdc++.6.0.9.tbd

5.开始实现语音，视频通话

1.初始化

@property (nonatomic, strong) RTCICEServer *iceServer;
@property (nonatomic, strong) RTCPeerConnectionFactory *pcFactory;
@property (nonatomic, strong) RTCPeerConnection *peerConnection;
@property (nonatomic, strong) RTCVideoTrack *localVideoTrack;
@property (nonatomic, strong) RTCVideoTrack *remoteVideoTrack;
@property (nonatomic, strong) RTCMediaConstraints *sdpConstraints;

@property (nonatomic, strong) RTCAudioTrack *localAudioTrack;
@property (nonatomic, strong) RTCAudioTrack *remoteAudioTrack;

NSString *videoEnable = self.audioOrVideoType == CXIMMediaCallTypeAudio ? @"false" : @"true";
self.sdpConstraints = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:
@[
[[RTCPair alloc] initWithKey:@"OfferToReceiveAudio" value:@"true"],
[[RTCPair alloc] initWithKey:@"OfferToReceiveVideo" value:videoEnable]
]
optionalConstraints: nil];

self.iceServer = [[RTCICEServer alloc] initWithURI:[NSURL URLWithString:kICEServer_URL] username:kICEServer_UserName password:kICEServer_Password];
[RTCPeerConnectionFactory initializeSSL];
self.pcFactory = [[RTCPeerConnectionFactory alloc] init];
RTCMediaConstraints *constraints = [[RTCMediaConstraints alloc] init];

//发起方第二个任务第一步，发起方创建RTCPeerConnection对象时设置了onicecandidate handler,hander被调用当candidates找到了的时候
_peerConnection = [self.pcFactory peerConnectionWithICEServers:@[self.iceServer] constraints:constraints delegate:self];

//添加Stream
RTCMediaStream *localStream = [self.pcFactory mediaStreamWithLabel:@"ARDAMS"];
RTCAudioTrack *audioTrack = [self.pcFactory audioTrackWithID:@"ARDAMSa0"];
self.localAudioTrack = audioTrack;
[localStream addAudioTrack:audioTrack];

if(self.audioOrVideoType == CXIMMediaCallTypeVideo){
AVCaptureDevice *device;
for (AVCaptureDevice *captureDevice in [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] ) {
if (captureDevice.position == AVCaptu
3ff8
reDevicePositionFront) {
device = captureDevice;
break;
}
}
if (device) {
RTCVideoSource *videoSource;
RTCVideoCapturer *capturer = [RTCVideoCapturer capturerWithDeviceName:device.localizedName];
videoSource = [self.pcFactory videoSourceWithCapturer:capturer constraints:constraints];
RTCVideoTrack *videoTrack = [self.pcFactory videoTrackWithID:@"ARDAMSv0" source:videoSource];
self.localVideoTrack = videoTrack;
[localStream addVideoTrack:videoTrack];
}
}

[_peerConnection addStream:localStream];

self.rtcIsClosed = NO;

2.第一个任务第一步发起方创建offer(即SDP会话描述)

[self.peerConnection createOfferWithDelegate:self constraints:self.sdpConstraints];

3.第二步，发起方成功创建offer之后，根据offer设置本地描述

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didCreateSessionDescription:(RTCSessionDescription *)sdp
error:(NSError *)error{
if(error){
NSLog(@"%@",error);
return;
}
//根据offer设置本地描述
[peerConnection setLocalDescriptionWithDelegate:self sessionDescription:sdp];
}

4.第三步，发起方创建本地信令描述成功后，发送本地offer给接受方

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didSetSessionDescriptionWithError:(NSError *)error{
if (error) {
NSLog(@"%@",error.userInfo[@"error"]);
return;
}

if (peerConnection.signalingState == RTCSignalingHaveLocalOffer) {
NSDictionary *sdp = @{
@"type":peerConnection.localDescription.type,
@"sdp":peerConnection.localDescription.description
};
//这里处理发送本地offer给接受方
}
}

5.第四步，接收方根据接受到的发起方的offer设置本地描述

RTCSessionDescription *remoteSdp = [[RTCSessionDescription alloc] initWithType:sdp[@"type"] sdp:sdp[@"sdp"]];
[self.peerConnection setRemoteDescriptionWithDelegate:self sessionDescription:remoteSdp];

6.第五步，接收方创建本地描述成功后，创建answer

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didSetSessionDescriptionWithError:(NSError *)error{
if (error) {
NSLog(@"%@",error.userInfo[@"error"]);
return;
}
else if(peerConnection.signalingState == RTCSignalingHaveRemoteOffer){
//创建answer
[peerConnection createAnswerWithDelegate:self constraints:self.sdpConstraints];
}
}

7.第六步，接收方创建answer后设置本地描述

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didCreateSessionDescription:(RTCSessionDescription *)sdp
error:(NSError *)error{
if(error){
NSLog(@"%@",error);
return;
}
//根据answer设置本地描述
[peerConnection setLocalDescriptionWithDelegate:self sessionDescription:sdp];
}

8.第七步，接收方设置本地描述成功后

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didSetSessionDescriptionWithError:(NSError *)error{
if (error) {
NSLog(@"%@",error.userInfo[@"error"]);
return;
}

else if(peerConnection.signalingState == RTCSignalingStable){
if(self.initiateOrAcceptCallType == SDIMCallAcceptType){
NSDictionary *sdp = @{
@"type":peerConnection.localDescription.type,
@"sdp":peerConnection.localDescription.description
};
//这里处理发送本地answer给发起方
}
}
}

9.第八步，发起方收到接受方的answer，发起方根据answer设置本地描述

RTCSessionDescription *remoteSdp = [[RTCSessionDescription alloc] initWithType:sdp[@"type"] sdp:sdp[@"sdp"]];
[self.peerConnection setRemoteDescriptionWithDelegate:self sessionDescription:remoteSdp];

10.第九步，发起方设置answer本地描述成功，确定本地媒体条件完成

- (void)peerConnection:(RTCPeerConnection *)peerConnection
didSetSessionDescriptionWithError:(NSError *)error{
if (error) {
NSLog(@"%@",error.userInfo[@"error"]);
return;
}
}

11.第二个任务，第一步发现Ice candidate时发送给接收方

// New Ice candidate have been found.
- (void)peerConnection:(RTCPeerConnection *)peerConnection
gotICECandidate:(RTCICECandidate *)candidate{
NSLog(@"%s",__func__);
NSDictionary *candidateInfo = @{
@"sdpMid":candidate.sdpMid,
@"sdpMLineIndex":@(candidate.sdpMLineIndex),
@"candidate":candidate.sdp
};
//在这里处理发起方发送Ice candidate给接收方
}

12.第二步，接收方收到Ice candidate后add起来

NSDictionary *candidateInfo = body.data[@"candidate"];
NSString *sdpMid = candidateInfo[@"sdpMid"];
NSInteger sdpMLineIndex = [candidateInfo[@"sdpMLineIndex"] integerValue];
NSString *sdp = candidateInfo[@"candidate"];
RTCICECandidate *candidate = [[RTCICECandidate alloc] initWithMid:sdpMid index:sdpMLineIndex sdp:sdp];
[self.peerConnection addICECandidate:candidate];

13.第三步，发起方接收方收到连接结果

- (void)peerConnection:(RTCPeerConnection *)peerConnection
iceConnectionChanged:(RTCICEConnectionState)newState{

// 连接成功
if(newState == RTCICEConnectionConnected){

}
//连接失败
else if (newState == RTCICEConnectionFailed || newState == RTCICEConnectionDisconnected || newState == RTCICEConnectionClosed){

}
}