webRTC 本地流创建，摄像头切换

一、本地流创建，属性声明：

//音视频标识
#define KT_STREAM   @"CCSTREAM"

#define KT_VIDEO_0  @"CCVideo_0"
#define KT_AUDIO_0  @"CCAUDIO_0"

@interface ConferenceStreamViewController () 
//数据源
@property(nonatomic,strong)RTCVideoSource *source;
//capture
@property(nonatomic,strong)RTCCameraVideoCapturer *capturer;
//Peer 工厂
@property(nonatomic,strong)RTCPeerConnectionFactory *factory;
//本地流
@property(nonatomic,strong)RTCMediaStream *rtcLocalStream;
//标记前后摄像头
@property(nonatomic,assign)BOOL _usingFrontCamera;

@end

二、创建本地流并推流

-(void)doPublishMedia
{
  if (_rtcLocalStream == nil)
  {
    //如果为空，则创建点对点工厂
    if (!_factory)
    {
      _factory = [RTCPeerConnectionFactory sharedInstance];
    }
    NSArray<AVCaptureDevice *> *captureDevices = [RTCCameraVideoCapturer captureDevices];
    AVCaptureDevicePosition position = _usingFrontCamera ? AVCaptureDevicePositionFront : AVCaptureDevicePositionBack;

    AVCaptureDevice * device = captureDevices[0];
    for (AVCaptureDevice *obj in captureDevices) 
  {
      if (obj.position == position) 
      {
        device = obj;
        break;
      }
   }
    //检测摄像头权限
    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied)
    {
      NSLog(@"相机访问受限");
    }
    else
    {
      if (device)
      {
        //创建本地流
        _rtcLocalStream = [_factory mediaStreamWithStreamId:KT_STREAM];
        //获取数据源
        _source = [_factory videoSource];
        
        //音频
        RTCAudioTrack * audioTrack = [_factory audioTrackWithTrackId:KT_AUDIO_0];
        //视频
        RTCVideoTrack *videoTrack = [_factory videoTrackWithSource:_source trackId:KT_VIDEO_0];
        //将audioTrack、videoTrack添加到流
        [_rtcLocalStream addAudioTrack:audioTrack];
        [_rtcLocalStream addVideoTrack:videoTrack];
        //拿到capture对象
        RTCCameraVideoCapturer * capture = [[RTCCameraVideoCapturer alloc] initWithDelegate:_source];
        AVCaptureDeviceFormat * format = [[RTCCameraVideoCapturer supportedFormatsForDevice:device] lastObject];
        CGFloat fps = [[format videoSupportedFrameRateRanges] firstObject].maxFrameRate;
        
        _capturer = capture;
        [capture startCaptureWithDevice:device format:format fps:fps completionHandler:^(NSError * error) {
          NSLog(@"startCaptureWithDevice---：%@",error);
        
          dispatch_async(dispatch_get_main_queue(), ^{
            //展示预览  
            [((StreamView *)self.view).localVideoView setCaptureSession:[_capturer captureSession] ];
          });
        }];
      }
      else
      {
        NSLog(@"该设备不能打开摄像头");
      }
    }
    //设置音视频编码格式
    ICSStreamSourceInfo *sInfo = [[ICSStreamSourceInfo alloc]init];
    sInfo.audio = ICSAudioCodecOpus;
    sInfo.video = ICSVideoCodecH264;
    //创建ICSLocalStream 流
    _localStream = [[ICSLocalStream alloc]initWithMediaStream:_rtcLocalStream source:sInfo];
#pragma mark
    
    ICSPublishOptions* options=[[ICSPublishOptions alloc] init];
    ICSAudioCodecParameters* opusParameters=[[ICSAudioCodecParameters alloc] init];
    opusParameters.name=ICSAudioCodecOpus;
    ICSAudioEncodingParameters *audioParameters=[[ICSAudioEncodingParameters alloc] init];
    audioParameters.codec=opusParameters;
    //设置音频码率
    audioParameters.maxBitrate = 50;
    
    options.audio=[NSArray arrayWithObjects:audioParameters, nil];
    ICSVideoCodecParameters *h264Parameters=[[ICSVideoCodecParameters alloc] init];
    h264Parameters.name=ICSVideoCodecH264;
    ICSVideoEncodingParameters *videoParameters=[[ICSVideoEncodingParameters alloc]init];
    videoParameters.codec=h264Parameters;
    //设置视频码率
    //这里一定要设置，不然推流一会儿就会因码率太高而卡死
    videoParameters.maxBitrate = 200;
    options.video=[NSArray arrayWithObjects:videoParameters, nil];
    
    [_conferenceClient publish:_localStream withOptions:options onSuccess:^(ICSConferencePublication* p) {
      _publication=p;
      _publication.delegate=self;
      
      dispatch_async(dispatch_get_main_queue(), ^{
        NSLog(@"publish success!");
      });
    } onFailure:^(NSError* err) {
      NSLog(@"publish failure!");
    }];
  }
}

三、切换摄像头

/**
 * 切换摄像头
 */
- (void)swichCamera
{
  _usingFrontCamera = !_usingFrontCamera;
  [self localSwitchCamera];
}

/*** 切换本地视频流*/
-(void)localSwitchCamera
{
  NSArray<AVCaptureDevice *> *captureDevices = [RTCCameraVideoCapturer captureDevices];
  AVCaptureDevicePosition position = _usingFrontCamera ? AVCaptureDevicePositionFront : AVCaptureDevicePositionBack;
  AVCaptureDevice * device = captureDevices[0];
  for (AVCaptureDevice *obj in captureDevices) 
  {
    if (obj.position == position)
    {
      device = obj;
      break;
    }
  }
  //检测摄像头权限
  AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
  if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied)
  {
    NSLog(@"相机访问受限");
  }
  else
  {
    if (device)
    {
      AVCaptureDeviceFormat * format = [[RTCCameraVideoCapturer supportedFormatsForDevice:device] lastObject];
      CGFloat fps = [[format videoSupportedFrameRateRanges] firstObject].maxFrameRate;
      [_capturer startCaptureWithDevice:device format:format fps:fps completionHandler:^(NSError * error) {
        NSLog(@"11111111");
        
        dispatch_async(dispatch_get_main_queue(), ^{
          [((StreamView *)self.view).localVideoView setCaptureSession:[_capturer captureSession] ];
        });
      }];
    }
    else
    {
      NSLog(@"该设备不能打开摄像头");
    }
  }
}