AVCaptureMultipeerVideoDataOutput
Advertises one stream of video over a multipeer connection.
Use SGSMultipeerVideoMixer for an example of how to view.
Details
Multipeer connection stuff is abstracted inside an AVCaptureVideoDataOutput subclass so setup is easy using the normal AV pipeline:
// Create the AVCaptureSession
self.captureSession = [[AVCaptureSession alloc] init];
// Setup the preview view
AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
captureVideoPreviewLayer.frame = CGRectMake(0,0, 320, 320);
[self.previewView.layer addSublayer:captureVideoPreviewLayer];
// Create video device input
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *videoDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:nil];
[self.captureSession addInput:videoDeviceInput];
// Create output
AVCaptureMultipeerVideoDataOutput *multipeerVideoOutput = [[AVCaptureMultipeerVideoDataOutput alloc] initWithDisplayName:[[UIDevice currentDevice] name]];
[self.captureSession addOutput:multipeerVideoOutput];
[self.captureSession startRunning];Thats it! Look in the AVCaptureMultipeerVideoDataOutput class for more details on the format & size of the image sent. The NSData that gets sent over the wire is described below.
Peer Setup
The peer needs to be looking for service type 'multipeer-video'. If you use the built in browser viewcontroller (like SGSMultipeerVideoMixer uses) it will look something like this:
- (void) showAssistant {
MCBrowserViewController* browserVC = [[MCBrowserViewController alloc] initWithServiceType:@"multipeer-video" session:_session];
browserVC.delegate = self;
[self presentViewController:browserVC animated:YES completion:nil];
}AVCaptureMultipeerVideoDataOutput sends a NSDictionary structured like this:
- (void)session:(MCSession *)session didReceiveData:(NSData *)data fromPeer:(MCPeerID *)peerID {
NSDictionary* dict = (NSDictionary*) [NSKeyedUnarchiver unarchiveObjectWithData:data];
// the actual image data (as JPG)
UIImage* image = [UIImage imageWithData:dict[@"image"] scale:2.0];
// the current FPS
NSNumber* framesPerSecond = dict[@"framesPerSecond"];
// the timestamp of this frame
NSNumber* timestamp = dict[@"timestamp"];
}Advertiser Setup
Uses cocoapods, so just add to your Podfile
pod "AVCaptureMultipeerVideoDataOutput"
See the Sample project for an example implementation. To run the sample:
pod install
Then open 'MultipeerVideoOutputSample.xcworkspace'
To Do
- Expose more of the output format variables
- Implement the no-UI multipeer connectivity classes
Contact
PJ Gray
License
AVCaptureMultipeerVideoDataOutput is available under the MIT license. See the LICENSE file for more info.