Video Calling

ConnectyCube Video Calling P2P API is built on top of WebRTC protocol and based on top of WebRTC Mesh architecture.

Max people per P2P call is 4.

To get a difference between P2P calling and Conference calling please read our ConnectyCube Calling API comparison blog page.

Get started with SDK

Follow the Getting Started guide on how to connect ConnectyCube SDK and start building your first app.

Code samples

There are ready-to-go FREE code samples to help you better understand how to integrate video calling capabilities in your apps:

  • VideoChat code sample, Swift request


Installation with CocoaPods

CocoaPods is a dependency manager for Objective-C and Swift, which automates and simplifies the process of using 3rd-party frameworks or libraries like ConnectyCubeCalls in your projects. You can follow their getting started guide if you don’t have CocoaPods installed.

Copy and paste the following lines into your podfile:

pod 'ConnectyCube'
pod 'ConnectyCubeCalls'

Now you can install the dependencies in your project:

$ pod install

From now on, be sure to always open the generated Xcode workspace (.xcworkspace) instead of the project file when building your project.

Importing framework

At this point, everything is ready for you to start using ConnectyCube and ConnectyCubeCalls frameworks. Just import the frameworks wherever you need to use them:

#import <ConnectyCube/ConnectyCube.h>
#import <ConnectyCubeCalls/ConnectyCubeCalls.h>
import ConnectyCube
import ConnectyCubeCalls

Run script phase for archiving

Add a "Run Script Phase" to build phases of your project. Paste the following snippet into the script:

bash "${BUILT_PRODUCTS_DIR}/${FRAMEWORKS_FOLDER_PATH}/ConnectyCubeCalls.framework/strip-framework.sh"

This fixes the known Apple bug, that does not allow to publish archives to the App store with dynamic frameworks that contain simulator platforms. Script is designed to work only for archiving.

Swift namespacing

ConnectyCubeCalls framework supports simple swift names, which means that instead of, for example, CYBCallSession you can just type CallSession. Sometimes it might get you an error: __someclass__ is ambiguous for type lookup in this context, which means that there is another class with the same swift name, and they are conflicting (swift does not understand what class do you want in the current context to be):

Swift ambiguous name

In this case you must specify a namespace of that specific class with ., which has the same name as framework and will be:



ConnectyCube Chat API is used as a signaling transport for Video Calling API, so in order to start using Video Calling API you need to connect to Chat.


Before any interaction with ConnectyCubeCalls you need to initialize it once using the method below:

[CYBCallClient initializeRTC];


Logging is a powerful tool to see the exact flow of the ConnectyCubeCalls framework and analyze its decisions. By enabling logs you will be able to debug most issues, or perhaps help us analyze your problems.

Basic logs are enabled by default. To enable verbose logs use the method below:

[CYBCallConfig setLogLevel:CYBCallLogLevelVerboseWithWebRTC];

Here are all possible log levels to use:

  • CYBCallLogLevelNothing: turns off all logging
  • CYBCallLogLevelVerbose: basic logs from our framework (enabled by default)
  • CYBCallLogLevelVerboseWithWebRTC: verbose logs from our framework including all internal webrtc logging (might be helpful to debug some complicated problems with calls)

To get more info about active call you can also enable stats reporting.

Background mode

You can use our SDK in the background mode as well, however this requires you to add a specific app permissions. Under the app build settings, open the Capabilities tab. In this tab, turn on Background Modes and set the Audio, AirPlay and Picture in Picture checkbox to set the audio background mode.

Background modes

If everything is correctly configured, iOS provides an indicator that your app is running in the background with an active audio session. This is seen as a red background of the status bar, as well as an additional bar indicating the name of the app holding the active audio session — in this case, your app.

Client delegate

In order to operate and receive calls you need to setup client delegate. Your class must conform to CYBCallClientDelegate protocol. Use the method below to subscribe:

[[CYBCallClient instance] addDelegate:self];

Initiate a call

In order to perform a call, use CYBCallClient and CYBCallSession methods below:

// 2123, 2123, 3122 - opponent's
NSArray *opponentsIDs = @[@3245, @2123, @3122];
CYBCallSession *newSession = [[CYBCallClient instance] createNewSessionWithOpponents:opponentsIDs withConferenceType:CYBCallConferenceTypeVideo];
// userInfo - the custom user information dictionary for the call. May be nil.
NSDictionary *userInfo = @{ @"key" : @"value" }; // optional
[newSession startCall:userInfo];
// 2123, 2123, 3122 - opponent's
let opponentsIDs = [3245, 2123, 3122]
let newSession = CallClient.instance().createNewSession(withOpponents: ids! as [NSNumber], with: .video)
// userInfo - the custom user information dictionary for the call. May be nil.
let userInfo = ["key":"value"] // optional

After this your opponents will receive one call request per 5 second for a duration of 45 seconds (you can configure these settings with CYBCallConfig):

- (void)didReceiveNewSession:(CYBCallSession *)session userInfo:(NSDictionary *)userInfo {
    if (self.session) {
        // we already have a video/audio call session, so we reject another one
        // userInfo - the custom user information dictionary for the call from caller. May be nil.
        NSDictionary *userInfo = @{ @"key" : @"value" }; // optional
        [session rejectCall:userInfo];
    // saving session instance here
    self.session = session;
func didReceiveNewSession(_ session: CallSession, userInfo: [String : String]? = nil) {
   if self.session != nil {
       // we already have a video/audio call session, so we reject another one
       // userInfo - the custom user information dictionary for the call from caller. May be nil.
       let userInfo = ["key":"value"] // optional
   // saving session instance here
   self.session = session

self.session refers to the current session. Each particular audio - video call has a unique sessionID. This allows you to have more than one independent audio-video conferences. If you want to increase the call timeout, e.g. set to 60 seconds:

[CYBCallConfig setAnswerTimeInterval:60];

Default value is 45 seconds.

In case opponent did not respond to your call within a specific timeout time, the callback listed below will be called:

- (void)session:(CYBCallSession *)session userDidNotRespond:(NSNumber *)userID {
func session(_ session: CallSession, userDidNotRespond userID: NSNumber) {

Accept a call

In order to accept a call, use the CYBCallSession method below:

// userInfo - the custom user information dictionary for the accept call. May be nil.
NSDictionary *userInfo = @{ @"key" : @"value" }; // optional
[self.session acceptCall:userInfo];
// userInfo - the custom user information dictionary for the accept call. May be nil.
let userInfo = ["key":"value"] // optional

After this your opponent will receive an accept signal:

- (void)session:(CYBCallSession *)session acceptedByUser:(NSNumber *)userID userInfo:(NSDictionary *)userInfo {
func session(_ session: CallSession, acceptedByUser userID: NSNumber, userInfo: [String : String]? = nil) {

Reject a call

In order to reject a call, use the CYBCallSession method below:

// userInfo - the custom user information dictionary for the reject call. May be nil.
NSDictionary *userInfo = @{ @"key" : @"value" }; // optional
[self.session rejectCall:userInfo];

// and release session instance
self.session = nil;
// userInfo - the custom user information dictionary for the reject call. May be nil.
let userInfo = ["key":"value"] // optional

// and release session instance
self.session = nil

After this your opponent will receive a reject signal:

- (void)session:(CYBCallSession *)session rejectedByUser:(NSNumber *)userID userInfo:(NSDictionary *)userInfo  {
    NSLog(@"Rejected by user %@", userID);
func session(_ session: CallSession, rejectedByUser userID: NSNumber, userInfo: [String : String]? = nil) {
    print("Rejected by user \(userID)")

End a call

In order to end a call, use the CYBCallSession method below:

// userInfo - the custom user information dictionary for the reject call. May be nil.
NSDictionary *userInfo = @{ @"key" : @"value" }; // optional
[self.session hangUp:userInfo];

// and release session instance
self.session = nil;
// userInfo - the custom user information dictionary for the reject call. May be nil.
let userInfo = ["key":"value"] // optional

// and release session instance
self.session = nil

After this your opponent will receive a hangup signal:

- (void)session:(CYBCallSession *)session hungUpByUser:(NSNumber *)userID userInfo:(NSDictionary<NSString *,NSString *> *)userInfo {
func session(_ session: CallSession, hungUpByUser userID: NSNumber, userInfo: [String : String]? = nil) {

Connection life cycle

All starts when you have received new session and accepted the call. The first thing you will get is startedConnectingToUser callback:

- (void)session:(__kindof CYBCallBaseSession *)session startedConnectingToUser:(NSNumber *)userID {
func session(_ session: CallBaseSession, startedConnectingToUser userID: NSNumber) {

After that webrtc will perform all operations that needed to connect both users internally, and you will either get connectedToUser or connectionFailedForUser (you will also receive this callback before connectionClosedForUser if connection failed during active call) if connection failed to connect for some reason:

- (void)session:(__kindof CYBCallBaseSession *)session connectedToUser:(NSNumber *)userID {

- (void)session:(__kindof CYBCallBaseSession *)session connectionFailedForUser:(NSNumber *)userID {
func session(_ session: CallBaseSession, connectedToUser userID: NSNumber) {

func session(_ session: CallBaseSession, connectionFailedForUser userID: NSNumber) {

When you or your opponent close the call, you will receive disconnectedFromUser callback first, and then connectionClosedForUser when connection is fully closed:

- (void)session:(__kindof CYBCallBaseSession *)session disconnectedFromUser:(NSNumber *)userID {

- (void)session:(__kindof CYBCallBaseSession *)session connectionClosedForUser:(NSNumber *)userID {
func session(_ session: CallBaseSession, disconnectedFromUser userID: NSNumber) {

func session(_ session: CallBaseSession, connectionClosedForUser userID: NSNumber) {

Session states

Each session has its own state. You can always access current state by simply calling the CYBCallSession property:

CYBCallSessionState sessionState = self.session.state;
let sessionState = self.session.state

You can also receive a live time callbacks on session changing its own state:

- (void)session:(CYBCallSession *)session didChangeState:(CYBCallSessionState)state {
func session(_ session: CallBaseSession, didChange state: CallSessionState) {

Here are all possible states that can occur:

  • CYBCallSessionStateNew: session was successfully created and ready for the next step
  • CYBCallSessionStatePending: session is in pending state for other actions to occur
  • CYBCallSessionStateConnecting: session is in progress of establishing connection
  • CYBCallSessionStateConnected: session was successfully established
  • CYBCallSessionStateClosed: session was closed

Connection state

Each user connection has its own state. By default you can access that state by calling this method from CYBCallSession:

NSNumber *userID = @(20450); // user with ID 20450
CYBCallConnectionState connectionState = [self.session connectionStateForUser:userID];
let userID = 20450 as NSNumber // user with ID 20450
let connectionState = self.session.connectionState(forUser: userID)

There is also a callback about connection state being changed in the live time:

- (void)session:(CYBCallSession *)session didChangeConnectionState:(CYBCallConnectionState)state forUser:(NSNumber *)userID {
func session(_ session: CallSession, didChange state: CallConnectionState, forUser userID: NSNumber) {

Here are all possible connection states that can occur:

  • CYBCallConnectionUnknown: connection state is unknown; this can occur when none of the other states are fit for the current situation
  • CYBCallConnectionNew: connection was created and ready for the next step
  • CYBCallConnectionPending: connection is in pending state for other actions to occur
  • CYBCallConnectionConnecting: one or more of the ICE transports are currently in the process of establishing a connection
  • CYBCallConnectionChecking: the ICE agent has been given one or more remote candidates and is checking pairs of local and remote candidates against one another to try to find a compatible match, but has not yet found a pair which will allow the peer connection to be made; it's possible that gathering of candidates is also still underway
  • CYBCallConnectionConnected: connection was performed successfully
  • CYBCallConnectionDisconnected: disconnected, but not closed; can still be reconnected
  • CYBCallConnectionClosed: connection was closed
  • CYBCallConnectionCount: ICE connection reached max numbers
  • CYBCallConnectionStateDisconnectTimeout: connection was disconnected by timeout
  • CYBCallConnectionStateNoAnswer: connection did not receive answer from the opponent user
  • CYBCallConnectionStateRejected: connection was rejected by the opponent user
  • CYBCallConnectionStateHangUp: connection was hanged up by the opponent user
  • CYBCallConnectionStateFailed: one or more of the ICE transports on the connection is in the failed state; this can occur on the different circumstances, e.g. bad network etc.

Show local video

In order to show your local video track from camera you should create UIView on storyboard and then use the following code:

// your view controller interface code

@interface CallController()
@property (weak, nonatomic) IBOutlet UIView *localVideoView; // your video view to render local camera video stream
@property (strong, nonatomic) CYBCallCameraCapture *videoCapture;
@property (strong, nonatomic) CYBCallSession *session;

@implementation CallController

- (void)viewDidLoad {
    [super viewDidLoad];
    [[CYBCallClient instance] addDelegate:self];

    CYBCallVideoFormat *videoFormat = [[CYBCallVideoFormat alloc] init];
    videoFormat.frameRate = 30;
    videoFormat.pixelFormat = CYBCallPixelFormat420f;
    videoFormat.width = 640;
    videoFormat.height = 480;

    // CYBCallCameraCapture class used to capture frames using AVFoundation APIs
    self.videoCapture = [[CYBCallCameraCapture alloc] initWithVideoFormat:videoFormat position:AVCaptureDevicePositionFront]; // or AVCaptureDevicePositionBack

    // add video capture to session's local media stream
    self.session.localMediaStream.videoTrack.videoCapture = self.videoCapture;

    self.videoCapture.previewLayer.frame = self.localVideoView.bounds;
    [self.videoCapture startSession];

    [self.localVideoView.layer insertSublayer:self.videoCapture.previewLayer atIndex:0];

   // start call

// ...

// your view controller interface code

import Foundation

class CallController: UIViewController, CallClientDelegate {

    @IBOutlet weak var localVideoView : UIView! // your video view to render local camera video stream

    var videoCapture: CallCameraCapture?
    var session: CallSession?

    override func viewDidLoad() {

        let videoFormat = VideoFormat.init()
        videoFormat.frameRate = 30
        videoFormat.pixelFormat = .format420f
        videoFormat.width = 640
        videoFormat.height = 480

        // CYBCallCameraCapture class used to capture frames using AVFoundation APIs
        self.videoCapture = CallCameraCapture.init(videoFormat: videoFormat, position: .front)

        // add video capture to session's local media stream
        self.session?.localMediaStream.videoTrack.videoCapture = self.videoCapture

        self.videoCapture?.previewLayer.frame = self.localVideoView.bounds

        self.localVideoView.layer.insertSublayer(self.videoCapture!.previewLayer, atIndex: 0)

        // start call


Show remote video

In order to show video views with streams which you have received from your opponents you should create CYBCallRemoteVideoView views on storyboard and then use the following code:

- (void)session:(CYBCallSession *)session receivedRemoteVideoTrack:(CYBCallVideoTrack *)videoTrack fromUser:(NSNumber *)userID {
    // we suppose you have created UIView and set it's class to CYBCallRemoteVideoView class
    // also we suggest you to set view mode to UIViewContentModeScaleAspectFit or
    // UIViewContentModeScaleAspectFill
    [self.opponentVideoView setVideoTrack:videoTrack];
func session(_ session: CallBaseSession, receivedRemoteVideoTrack videoTrack: CallVideoTrack, fromUser userID: NSNumber) {
   // we suppose you have created UIView and set it's class to RemoteVideoView class
   // also we suggest you to set view mode to UIViewContentModeScaleAspectFit or
   // UIViewContentModeScaleAspectFill

You can always get remote video tracks for a specific user ID in the call using these CYBCallSession methods (assuming that they are existent):

CYBCallVideoTrack *remoteVideoTrack = [self.session remoteVideoTrackWithUserID:@(24450)]; // video track for user 24450
let remoteVideoTrack = self.session?.remoteVideoTrack(withUserID: 24450) // video track for user 24450

Mute audio

You can disable/enable audio during a call:

self.session.localMediaStream.audioTrack.enabled ^= 1;
self.session?.localMediaStream.audioTrack.enabled = !self.session?.localMediaStream.audioTrack.enabled

Mute remote audio

You can always get remote audio tracks for a specific user ID in the call using these CYBCallSession methods (assuming that they are existent):

CYBCallAudioTrack *remoteAudioTrack = [self.session remoteAudioTrackWithUserID:@(24450)]; // audio track for user 24450
let remoteAudioTrack = self.session?.remoteAudioTrack(withUserID: 24450) // audio track for user 24450

You can also mute remote media tracks on your side, by changing value of enabled property for a specific remote media track:

remoteAudioTrack.enabled = NO;
remoteAudioTrack.enabled = false

CYBCallAudioTrack class (that represents remote audio track for a specific user) supports audio data sink through CYBCallAudioTrackSinkInterface protocol. In order to access audio data in real time, simply subscribe to sink interface using methods:

 *  Add sink.
 *  @param sink class instance that conforms to CYBCallAudioTrackSinkInterface protocol
 *  @see CYBCallAudioTrackSinkInterface
- (void)addSink:(id<CYBCallAudioTrackSinkInterface>)sink;

 *  Remove sink.
 *  @param sink class instance that conforms to CYBCallAudioTrackSinkInterface protocol
 *  @see CYBCallAudioTrackSinkInterface
- (void)removeSink:(id<CYBCallAudioTrackSinkInterface>)sink;

Now handle protocol method to access audio data:

- (void)audioTrack:(CYBCallAudioTrack *)audioTrack didSinkAudioBufferList:(const AudioBufferList *)audioBufferList audioStreamDescription:(const AudioStreamBasicDescription)audioStreamDescription numberOfFrames:(size_t)numberOfFrames time:(CMTime)time {
func audioTrack(_ audioTrack: CallAudioTrack, didSinkAudioBufferList audioBufferList: UnsafePointer<AudioBufferList>, audioStreamDescription: AudioStreamBasicDescription, numberOfFrames: Int, time: CMTime) {


This interface provides AudioBufferList with audio data, AudioStreamBasicDescription description of audio data, a number of frames in current packet, and current media time that conforms to each packet.

Mute video

You can disable/enable video during a call:

self.session.localMediaStream.videoTrack.enabled ^= 1;
self.session?.localMediaStream.videoTrack.enabled = !self.session?.localMediaStream.videoTrack.enabled


Due to webrtc restrictions black frames will be placed into stream content if video is disabled.

Switch camera

You can switch the video capture position during a call (default: front camera):

// to change some time after, for example, at the moment of call
AVCaptureDevicePosition position = self.videoCapture.position;
AVCaptureDevicePosition newPosition = position == AVCaptureDevicePositionBack ? AVCaptureDevicePositionFront : AVCaptureDevicePositionBack;

// check whether videoCapture has or has not camera position
// for example, some iPods do not have front camera
if ([self.videoCapture hasCameraForPosition:newPosition]) {
    self.videoCapture.position = newPosition;
// to change some time after, for example, at the moment of call
let position = self.videoCapture?.position
let newPosition = position == AVCaptureDevice.Position.Front ? AVCaptureDevice.Position.Back : AVCaptureDevice.Position.Front

// check whether videoCapture has or has not camera position
// for example, some iPods do not have front camera
if self.videoCapture?.hasCameraForPosition(newPosition) {
    self.videoCapture?.position = newPosition

Audio session management

ConnectyCubeCalls has its own audio session management which you need to use. It's located in CYBCallAudioSession class. This class represented as singleton and you can always access shared session by calling instance method:

CYBCallAudioSession *audioSession = [CYBCallAudioSession instance];
let audioSession = CallAudioSession.instance()

See CYBCallAudioSession class header for more information.

Initialization and deinitialization

You must initialize audio session before every call:

[[CYBCallAudioSession instance] initializeWithConfigurationBlock:^(CYBCallAudioSessionConfiguration *configuration) {
    // adding blutetooth support
    configuration.categoryOptions |= AVAudioSessionCategoryOptionAllowBluetooth;
    configuration.categoryOptions |= AVAudioSessionCategoryOptionAllowBluetoothA2DP;

    // adding airplay support
    configuration.categoryOptions |= AVAudioSessionCategoryOptionAllowAirPlay;
    configuration.mode = AVAudioSessionModeVideoChat; // setting mode to video chat to enable airplay audio and speaker only for video call
CallAudioSession.instance().initialize { (configuration: CallAudioSessionConfiguration) -> () in

    var options = configuration.categoryOptions
    if #available(iOS 10.0, *) {
        // adding blutetooth support
        options = options.union(AVAudioSessionCategoryOptions.allowBluetoothA2DP)
        // adding airplay support
        options = options.union(AVAudioSessionCategoryOptions.allowAirPlay)
    } else {
        // adding blutetooth support
        options = options.union(AVAudioSessionCategoryOptions.allowBluetooth)

    configuration.categoryOptions = options
    configuration.mode = AVAudioSessionModeVideoChat // setting mode to video chat to enable airplay audio and speaker only for video call

And deinitialize it after the call ends:

[[CYBCallAudioSession instance] deinitialize];

Audio output

You can output audio either from receiver (unless you set mode AVAudioSessionModeVideoChat) or speaker:

CYBCallAudioSession *audioSession = [CYBCallAudioSession instance];
// setting audio through receiver
audioSession.currentAudioDevice = CYBCallAudioDeviceReceiver;
// setting audio through speaker
audioSession.currentAudioDevice = CYBCallAudioDeviceSpeaker;
let audioSession = CallAudioSession.instance()
// setting audio through receiver
audioSession.currentAudioDevice = .receiver
// setting audio through speaker
audioSession.currentAudioDevice = .speaker

Screen sharing

Screen sharing allows you to share information from your application to all of your opponents. It gives you an ability to promote your product, share a screen with formulas to students, distribute podcasts, share video/audio/photo moments of your life in real-time all over the world.


Due to Apple iOS restrictions screen sharing feature works only within an app you are using it in.

To implement this feature in your application we give you the ability to create custom video capture.

Video capture is a base class you should inherit from in order to send frames to your opponents.

There are two ways to implement this feature in your application.

iOS 11 and newer

With iOS 11 Apple has introduced a new way to capture your in-app screen using ReplayKit's RPScreenRecorder class. This is the most optimal way to share screen and requires minimum resources as this is handled by iOS itself. However, the minimum requirenment is iOS 11.

if ([UIDevice currentDevice].systemVersion.integerValue >= 11) {
    self.screenCapture = [[CYBCallVideoCapture alloc] init];

    [RPScreenRecorder.sharedRecorder startCaptureWithHandler:^(CMSampleBufferRef  _Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error) {
        switch (bufferType) {
            case RPSampleBufferTypeVideo: {
                CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
                CYBCallVideoFrame *frame = [[CYBCallVideoFrame alloc] initWithPixelBuffer:pixelBuffer videoRotation:CYBCallVideoRotation_0];
                [self.screenCapture adaptOutputFormatToWidth:(NSUInteger)[UIScreen mainScreen].bounds.size.width height:(NSUInteger)[UIScreen mainScreen].bounds.size.height fps:30];
                [self.screenCapture sendVideoFrame:frame];
    } completionHandler:^(NSError * _Nullable error) {
        NSLog(@"error: %@", error);

    self.session.localMediaStream.videoTrack.videoCapture = self.screenCapture;
if #available(iOS 11.0, *) {
    self.screenCapture = CallVideoCapture()

    RPScreenRecorder.shared().startCapture(handler: { (sampleBuffer, type, error) in

        switch type {
        case .video :
            let source = CMSampleBufferGetImageBuffer(sampleBuffer)
            let frame = CallVideoFrame(pixelBuffer: source, videoRotation: ._0)
            self.screenCapture.adaptOutputFormat(toWidth: UInt(UIScreen.main.bounds.width), height: UInt(UIScreen.main.bounds.height), fps: 30)


    }) { (error) in
        if (error != nil) {

self.session?.localMediaStream.videoTrack.videoCapture = self.screenCapture

self.screenCapture should be a property of CYBCallVideoCapture class type.


30 fps is a maximum webrtc can go, even though RPScreenRecorder supports 60, you must set it to 30 or lower.

iOS 10 and older

This one is a little bit tricky and you won't be able to achieve resource-free 30 fps screen sharing with this. The most frames per second we recommend using this method is 5, as this is very resource heave operation.

CYBCallVideoCapture class allows sending frames to your opponents. By inheriting this class you are able to provide custom logic to create frames, modify them and then send to your opponents. Below you can find an example of how to implement a custom video capture and send frames to your opponents (this class is designed to share 5 screenshots per second):

 *  By default sending frames in screen sharing is using BiPlanarFullRange pixel format type.
 *  You can also send them using ARGB by setting this constant to NO.
static const BOOL kCYBCallUseBiPlanarFormatTypeForShare = YES;

@interface CYBCallScreenCapture()

@property (weak, nonatomic) UIView * view;
@property (strong, nonatomic) CADisplayLink *displayLink;


@implementation CYBCallScreenCapture

- (instancetype)initWithView:(UIView *)view {

    self = [super init];
    if (self) {

        _view = view;

    return self;

#pragma mark - Enter BG / FG notifications

- (void)willEnterForeground:(NSNotification *)note {

    self.displayLink.paused = NO;

- (void)didEnterBackground:(NSNotification *)note {

    self.displayLink.paused = YES;

#pragma mark -

- (UIImage *)screenshot {

    UIGraphicsBeginImageContextWithOptions(_view.frame.size, YES, 1);
    [_view drawViewHierarchyInRect:_view.bounds afterScreenUpdates:NO];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    return image;

- (CIContext *)CYBCall_sharedGPUContext {
    static CIContext *sharedContext;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        NSDictionary *options = @{
                                  kCIContextPriorityRequestLow: @YES
        sharedContext = [CIContext contextWithOptions:options];
    return sharedContext;

- (void)sendPixelBuffer:(CADisplayLink *)sender {

    dispatch_async(self.videoQueue, ^{

        @autoreleasepool {

            UIImage *image = [self screenshot];

            int renderWidth = image.size.width;
            int renderHeight = image.size.height;

            CVPixelBufferRef buffer = NULL;

            OSType pixelFormatType;
            CFDictionaryRef pixelBufferAttributes = NULL;
            if (kCYBCallUseBiPlanarFormatTypeForShare) {

                pixelFormatType = kCVPixelFormatType_420YpCbCr8BiPlanarFullRange;
                pixelBufferAttributes = (__bridge CFDictionaryRef) @
                    (__bridge NSString *)kCVPixelBufferIOSurfacePropertiesKey: @{},
            else {

                pixelFormatType = kCVPixelFormatType_32ARGB;
                pixelBufferAttributes = (__bridge CFDictionaryRef) @
                    (NSString *)kCVPixelBufferCGImageCompatibilityKey : @NO,
                    (NSString *)kCVPixelBufferCGBitmapContextCompatibilityKey : @NO


            CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault,

            if (status == kCVReturnSuccess && buffer != NULL) {

                CVPixelBufferLockBaseAddress(buffer, 0);

                if (kCYBCallUseBiPlanarFormatTypeForShare) {

                    CIImage *rImage = [[CIImage alloc] initWithImage:image];
                    [self.CYBCall_sharedGPUContext render:rImage toCVPixelBuffer:buffer];
                else {

                    void *pxdata = CVPixelBufferGetBaseAddress(buffer);

                    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();

                    uint32_t bitmapInfo = kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst;

                    CGContextRef context =
                    CGBitmapContextCreate(pxdata, renderWidth, renderHeight, 8, renderWidth * 4, rgbColorSpace, bitmapInfo);
                    CGContextDrawImage(context, CGRectMake(0, 0, renderWidth, renderHeight), [image CGImage]);

                CVPixelBufferUnlockBaseAddress(buffer, 0);

                CYBCallVideoFrame *videoFrame = [[CYBCallVideoFrame alloc] initWithPixelBuffer:buffer

                [super sendVideoFrame:videoFrame];


#pragma mark - <CYBCallVideoCapture>

- (void)didSetToVideoTrack:(CYBCallLocalVideoTrack *)videoTrack {
    [super didSetToVideoTrack:videoTrack];

    self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(sendPixelBuffer:)];
    [self.displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    self.displayLink.frameInterval = 12; //5 fps

    [[NSNotificationCenter defaultCenter] addObserver:self

    [[NSNotificationCenter defaultCenter] addObserver:self

- (void)didRemoveFromVideoTrack:(CYBCallLocalVideoTrack *)videoTrack {
    [super didRemoveFromVideoTrack:videoTrack];

    self.displayLink.paused = YES;
    [self.displayLink removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    self.displayLink = nil;

    [[NSNotificationCenter defaultCenter] removeObserver:self

    [[NSNotificationCenter defaultCenter] removeObserver:self

import UIKit

import ConnectyCubeCalls

class ScreenCapture: CallVideoCapture {

     *  By default sending frames in screen sharing is using BiPlanarFullRange pixel format type.
     *  You can also send them using ARGB by setting this constant to NO.
    let useBiPlanarFormatTypeForShare = true

    var view: UIView?
    var displayLink: CADisplayLink!

    private lazy var sharedGPUContext: CIContext = {
        CIContext(options: [kCIContextPriorityRequestLow : true])

    // MARK: Construction

    init(view: UIView) {
        self.view = view

    // MARK: Enter BG / FG notifications

    @objc func willEnterForeground(notification: NSNotification!) {
        self.displayLink.isPaused = false

    @objc func didEnterBackground(notification: NSNotification!) {
        self.displayLink.isPaused = true

    // MARK: Functions

    func screenshot() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.view!.frame.size, true, 1)
        self.view?.drawHierarchy(in: self.view!.bounds, afterScreenUpdates: false)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        return image!

    @objc func sendPixelBuffer(sender: CADisplayLink) {

        self.videoQueue.async {


                let image = self.screenshot()

                let renderWidth = image.size.width
                let renderHeight = image.size.height

                var buffer: CVPixelBuffer? = nil

                var pixelFormatType: OSType?
                var pixelBufferAttributes: CFDictionary? = nil

                if self.useBiPlanarFormatTypeForShare {
                    pixelFormatType = kCVPixelFormatType_420YpCbCr8BiPlanarFullRange
                    pixelBufferAttributes = [
                        String(kCVPixelBufferIOSurfacePropertiesKey) : [:]
                        ] as CFDictionary
                else {
                    pixelFormatType = kCVPixelFormatType_32ARGB
                    pixelBufferAttributes = [
                        String(kCVPixelBufferCGImageCompatibilityKey) : false,
                        String(kCVPixelBufferCGBitmapContextCompatibilityKey) : false
                        ] as CFDictionary

                let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(renderWidth), Int(renderHeight), pixelFormatType!, pixelBufferAttributes, &buffer)

                if status == kCVReturnSuccess && buffer != nil {

                    CVPixelBufferLockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))

                    if self.useBiPlanarFormatTypeForShare {

                        let rImage = CIImage(image: image)
                        self.sharedGPUContext.render(rImage!, to: buffer!)
                    else {

                        let pxdata = CVPixelBufferGetBaseAddress(buffer!)
                        let rgbColorSpace = CGColorSpaceCreateDeviceRGB()

                        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedFirst.rawValue)

                        let context = CGContext(data: pxdata, width: Int(renderWidth), height: Int(renderHeight), bitsPerComponent: 8, bytesPerRow: Int(renderWidth * 4), space: rgbColorSpace, bitmapInfo: bitmapInfo.rawValue)

                        context?.draw(image.cgImage!, in: CGRect(x: 0.0, y: 0.0, width: renderWidth, height: renderHeight))

                    CVPixelBufferUnlockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))

                    let videoFrame = CallVideoFrame(pixelBuffer: buffer, videoRotation: VideoRotation._0)


    // MARK: VideoCapture

    override func didSet(to videoTrack: CallLocalVideoTrack!) {
        super.didSet(to: videoTrack)

        self.displayLink = CADisplayLink(target: self, selector: #selector(sendPixelBuffer(sender:)))
        self.displayLink.add(to: RunLoop.main, forMode: RunLoopMode.commonModes)
        self.displayLink.frameInterval = 12 //5 fps

        NotificationCenter.default.addObserver(self, selector: #selector(willEnterForeground(notification:)), name: NSNotification.Name.UIApplicationWillEnterForeground, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(didEnterBackground(notification:)), name: NSNotification.Name.UIApplicationDidEnterBackground, object: nil)

    override func didRemove(from videoTrack: CallLocalVideoTrack!) {
        super.didRemove(from: videoTrack)

        self.displayLink.isPaused = true
        self.displayLink.remove(from: RunLoop.main, forMode: RunLoopMode.commonModes)
        self.displayLink = nil

        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIApplicationWillEnterForeground, object: nil)
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIApplicationDidEnterBackground, object: nil)

WebRTC stats reporting

Stats reporting is an insanely powerful tool which can help to debug a call if there are any problems with it (e.g. lags, missing audio/video etc.). To enable stats report you should first set stats reporting frequency using CYBCallConfig method below:

[CYBCallConfig setStatsReportTimeInterval:5]; // receive stats report every 5 seconds
CallConfig.setStatsReportTimeInterval(5) // receive stats report every 5 seconds

Now you will be able to receive a client delegate callback and perform operations with CYBCallStatsReport instance for the current period of time:

- (void)session:(CYBCallBaseSession *)session updatedStatsReport:(CYBCallStatsReport *)report forUserID:(NSNumber *)userID {
    NSLog(@"%@", [report statsString]);
func session(_ session: CallBaseSession, updatedStatsReport report: CallStatsReport, forUserID userID: NSNumber) {

By calling statsString you will receive a generic report string, which will contain the most useful data to debug a call, example:

CN 565ms | local->local/udp | (s)248Kbps | (r)869Kbps
VS (input) 640x480@30fps | (sent) 640x480@30fps
VS (enc) 279Kbps/260Kbps | (sent) 200Kbps/292Kbps | 8ms | H264
AvgQP (past 30 encoded frames) = 36
VR (recv) 640x480@26fps | (decoded)27 | (output)27fps | 827Kbps/0bps | 4ms
AS 38Kbps | opus
AR 37Kbps | opus | 168ms | (expandrate)0.190002
Packets lost: VS 17 | VR 0 | AS 3 | AR 0


CN - connection info, VS - video sent, VR - video received, AvgQP - average quantization parameter (only valid for video; it is calculated as a fraction of the current delta sum over the current delta of encoded frames; low value corresponds with good quality; the range of the value per frame is defined by the codec being used), AS - audio sent, AR - audio received.

You can also use stats reporting to see who is currently talking in a group call. You must use audioReceivedOutputLevel for that.

Take a look to the CYBCallStatsReport header file to see all of the other stats properties that might be useful for you.

Receive a call in background (CallKit)

For mobile apps, it can be a situation when an opponent's user app is either in closed (killed) or background (inactive) state.

In this case, to be able to still receive a call request, you can use Push Notifications. The flow should be as follows:

  • a call initiator should send a push notification along with a call request;
  • when an opponent's app is killed or in background state - an opponent will receive a push notification about an incoming call, and will be able to accept/reject the call. If accepted or pressed on a push notification - an app will be opened, a user should auto login and connect to chat and then will be able to join an incoming call;

Please refer to Push Notifications API guides regarding how to integrate Push Notifications in your app.

Apple CallKit using VOIP push notifications

ConnectyCubeCalls fully supports Apple CallKit. In this block, we will guide you through the most important things you need to know when integrating CallKit into your application (besides those Apple has already provided in the link above).

Project preparations

In your Xcode project, make sure that your app supports Voice over IP services. For that open your Info.plist and make sure you have a specific line in Required background modes array:

VOIP background mode

Now you are ready to integrate CallKit methods using Apple's guide here.

Managing audio session

CallKit requires you to manage Audio session by yourself. Use CYBCallAudioSession for that task. See Audio session management.

Initializing audio session

You must initialize audio session every time before you call -[CXProvider reportNewIncomingCallWithUUID:update:completion:] method, which shows incoming call screen. Before initializing audio session, set useManualAudio property value to YES. This will not activate webrtc audio before iOS allows us to. We will be activating audio manually later. See Audio session initialization for more information.

Managing audio session activations and deinitializing it

CXProviderDelegate has 2 delegate methods that you must conform to. These are -[CXProviderDelegate provider:didActivateAudioSession:] and -[CXProviderDelegate provider:didDeactivateAudioSession:]. Using CYBCallAudioSessionActivationDelegateprotocol of CYBCallAudioSession class, you need to notify that session was activated outside of it. -[CXProviderDelegate provider:didActivateAudioSession:] is also a delegate where we need to activate our audio manually. Set audioEnabledproperty of CYBCallAudioSession class in here, to enable webrtc audio as iOS have pushed audio session priority of our app to the top.

- (void)provider:(CXProvider *)__unused provider didActivateAudioSession:(AVAudioSession *)audioSession {
    NSLog(@"[CallKitManager] Activated audio session.");
    CYBCallAudioSession *callAudioSession = [CYBCallAudioSession instance];
    [callAudioSession audioSessionDidActivate:audioSession];
    // enabling audio now
    callAudioSession.audioEnabled = YES;
func provider(_ provider: CXProvider, didActivate audioSession: AVAudioSession) {
        print("[CallKitManager] Activated audio session.")
        let callAudioSession = CallAudioSession.instance()
        // enabling audio now
        callAudioSession.isAudioEnabled = true

Deinitialize audio session every time CXProvider deactivates it in -[CXProviderDelegate provider:didDeactivateAudioSession:] delegate. Deinitializing audio session earlier would lead to issues with the audio session.

- (void)provider:(CXProvider *)provider didDeactivateAudioSession:(AVAudioSession *)audioSession {
    NSLog(@"[CallKitManager] Dectivated audio session.");
    CYBCallAudioSession *callAudioSession = [CYBCallAudioSession instance];
    [callAudioSession audioSessionDidDeactivate:audioSession];
    // deinitializing audio session after iOS deactivated it for us
    if (callAudioSession.isInitialized) {
        NSLog(@"Deinitializing session in CallKit callback.");
        [callAudioSession deinitialize];
func provider(_ provider: CXProvider, didDeactivate audioSession: AVAudioSession) {
        print("[CallKitManager] Dectivated audio session.")
        let callAudioSession = CallAudioSession.instance()
        // deinitializing audio session after iOS deactivated it for us
        if (callAudioSession.isInitialized) {
            print("Deinitializing session in CallKit callback.");

If you also have deinitialization code of CYBCallAudioSession somewhere else in your app, you can check and ignore it with -[CYBCallAudioSessionActivationDelegate audioSessionIsActivatedOutside:] method. By this, you will know for sure that CallKit is in charge of your audio session. Don't forget to restore CYBCallAudioSession properties to default values in -[CXProviderDelegate provider:performEndCallAction:]:

- (void)provider:(CXProvider *)__unused provider performEndCallAction:(CXEndCallAction *)action {
    CYBCallAudioSession *audioSession = [CYBCallAudioSession instance];
    audioSession.audioEnabled = NO;
    audioSession.useManualAudio = NO;
    [action fulfillWithDateEnded:[NSDate date]];
func provider(_ provider: CXProvider, perform action: CXEndCallAction) {
        let audioSession = CallAudioSession.instance()
        audioSession.isAudioEnabled = false
        audioSession.useManualAudio = false
        action.fulfill(withDateEnded: Date())

Workaround for iOS 10 no sound bug

To avoid a no-sound bug on iOS 10 add this workaround to your CallKit manager. In -[CXProviderDelegate provider:performAnswerCallAction:] delegate callback force set category to AVAudioSessionCategoryPlayAndRecord.

For some reason on iOS 10, it is still incorrect here and takes time to set up after we initially performed audio session configuration with our CYBCallAudioSession instance. This leads to webrtc having problems with audio initialization on the incorrect category which, again, leads to no audio in the call.

- (void)provider:(CXProvider *)__unused provider performAnswerCallAction:(CXAnswerCallAction *)action {
    if ([UIDevice currentDevice].systemVersion.integerValue == 10) {
        // Workaround for webrtc on ios 10, because first incoming call does not have audio
        // due to incorrect category: AVAudioSessionCategorySoloAmbient
        // webrtc need AVAudioSessionCategoryPlayAndRecord
        NSError *err = nil;
        if (![[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:&err]) {
            NSLog(@"[CallKitManager] Error setting category for webrtc workaround.");

    [action fulfill];
@available(iOS 10.0, *)
func provider(_ provider: CXProvider, perform action: CXAnswerCallAction) {
    if (Int(UIDevice.current.systemVersion) == 10) {
        // Workaround for webrtc on ios 10, because first incoming call does not have audio
        // due to incorrect category: AVAudioSessionCategorySoloAmbient
        // webrtc need AVAudioSessionCategoryPlayAndRecord
        try! AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord)
        print("[CallKitManager] Error setting category for webrtc workaround.")


The issue does not exist on iOS 11 and higher according to our test results. So feel free to use this workaround for iOS 10 only.

Group video calls

Because of Mesh architecture we use for multipoint where every participant sends and receives its media to all other participants, current solution supports group calls with up to 4 people.

Also ConnectyCube provides an alternative solution for up to 12 people - Multiparty Video Conferencing API.


CYBCallRecorder class handles calls recording. You cannot allocate it by yourself, but it is stored in each instance of CYBCallSession by the property named recorder if the requirements conform. Otherwise, recorder property value will be nil.

Recorder requirements

  • Device must not be in a low-performance category. To check whether your device is in low performance category use UIDevice+CYBCallPerformance category property CYBCall_lowPerformance.
  • Only 1 to 1 audio and video calls are supported for now.


Once you have created new rtc session, you can start recorder by accessing recorder property in session instance. Call start method and input desired file url:

NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentPath = [searchPaths firstObject];
NSString *filePath = [NSString stringWithFormat:@"%@/file_%f.mp4", documentPath, [NSDate date].timeIntervalSince1970];
[self.session.recorder startRecordWithFileURL:[NSURL fileURLWithPath:filePath]];
let searchPaths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
let documentPath = searchPaths.first
let filePath = String(format: "%@/file_%f.mp4", documentPath!, Date().timeIntervalSince1970)
self.session?.recorder?.startRecord(withFileURL: URL(fileURLWithPath: filePath))

You can configure output file video settings and video orientation using these methods of CYBCallRecorder class:

 Set video recording format.

 @param width video width
 @param height video height
 @param bitrate video bitrate
 @param fps video fps

 @note You can only set this params while recording is not in active state (e.g. haven't started yet).

 @remark Default values are 640x480 with 636528 bitrate 30 fps

 @see https://www.dr-lex.be/info-stuff/videocalc.html for bitrate calculation
- (void)setVideoRecordingWidth:(NSUInteger)width

 Set video recording orientation.

 @param videoRotation video rotation

 @note You can only set this params while recording is not in active state (e.g. haven't started yet).
 Cannot be changed mid record.

 @remark Default is 0 degrees, e.g. landscape orientation.
- (void)setVideoRecordingRotation:(CYBCallVideoRotation)videoRotation;

Once the call is finished or whenever you want before that you need to simply call stop method:

[self.session.recorder stopRecord:^(NSURL *file) {
self.session?.recorder?.stopRecord({ (url) in


Stop method is asynchronous and will take some time to finalize record file. Once the completion block is called, recording file should be ready by expected url unless some error happens.

In order to handle any recorder errors, simply subscribe to delegate of CYBCallRecorder and handle this method:

- (void)recorder:(CYBCallRecorder *)recorder didFailWithError:(NSError *)error {
func recorder(_ recorder: CallRecorder, didFailWithError error: Error) {

Settings and configuration

You can change different settings for your calls using CYBCallConfig class. All of them are listed below:

Answer time interval

If an opponent did not answer you within dialing time interval, then userDidNotRespond: and then connectionClosedForUser: delegate methods will be called.

Default value: 45 seconds

Minimum value: 10 seconds

[CYBCallConfig setAnswerTimeInterval:45];

Dialing time interval

Indicates how often we send notifications to your opponents about your call.

Default value: 5 seconds

Minimum value: 3 seconds

[CYBCallConfig setDialingTimeInterval:5];

DTLS (Datagram Transport Layer Security)

Datagram Transport Layer Security (DTLS) is used to provide communications privacy for datagram protocols. This fosters a secure signaling channel that cannot be tampered with. In other words, no eavesdropping or message forgery can occur on a DTLS encrypted connection.

DTLS is enabled by default.

[CYBCallConfig setDTLSEnabled:YES];

Custom ICE servers

You can customize a list of ICE servers. By default ConnectyCubeCalls will use internal ICE servers which is usually enough, but you can always set your own.

Q: How does WebRTC select which TURN server to use if multiple options are given?

A: During the connectivity checking phase, WebRTC will choose the TURN relay with the lowest round-trip time. Thus, setting multiple TURN servers allows your application to scale-up in terms of bandwidth and number of users.

NSString *userName = @"turn_login";
NSString *password = @"turn_password";

NSArray *urls = @[

CYBCallICEServer *server = [CYBCallICEServer serverWithURLs:urls username:userName password:password];
[CYBCallConfig setICEServers:@[server]];
let username = "turn_login"
let password = "turn_password"

let urls = [

let server = CallICEServer.init(urls: urls, username: username, password: password)

Video codecs

You can choose video codecs from available values:

  • CYBCallVideoCodecVP8: VP8 video codec
  • CYBCallVideoCodecH264Baseline: h264 baseline video codec
  • CYBCallVideoCodecH264High: h264 high video codec

VP8 is software supported video codec on Apple devices, which means it is the most demanding among all available ones.

H264 is hardware supported video codec, which means that it is the most optimal one for use when performing video codec, using hardware acceleration you can always gurantee the best performance when encoding and decoding video frames. There are two options available:

  • baseline: the most suited one for video calls as it has low cost (default value)
  • high: mainly suited for broadcast to ensure you have the best picture possible. Takes more resources to encode/decode for the same resolution you set
[CYBCallConfig mediaStreamConfiguration].videoCodec = CYBCallVideoCodecH264Baseline;
CallConfig.mediaStreamConfiguration().videoCodec = .h264Baseline


This will set your preferred codec, as webrtc will always choose the most suitable one for both sides in call through negotiations.

Video quality

Video quality depends on hardware you use. iPhone 4s will not handle FullHD rendering, but iPhone 6+ will. It also depends on network you use and how many connections you have. For multi-calls set lower video quality. For 1 to 1 calls you can set higher quality.

You can use our CYBCallCameraCapture formatsWithPosition method in order to get all supported formats for current device:

 *  Retrieve available array of CYBCallVideoFormat instances for given camera position.
 *  @param position requested camera position
 *  @return Array of possible CYBCallVideoFormat video formats for requested position
+ (NSArray <CYBCallVideoFormat *> *)formatsWithPosition:(AVCaptureDevicePosition)position;

WebRTC has auto scaling of video resolution and quality to keep network connection active. To get best quality and performance you should use h264-baseline codec as your preferred one.

  1. If some opponent user in call does not support h264, then automatically VP8 will be used.
  2. If both caller and callee have h264 support, then h264 will be used.

Audio codecs

You can choose audio codecs from available values:

  • CYBCallAudioCodecOpus
  • CYBCallAudioCodecISAC
  • CYBCallAudioCodeciLBC

Default value: CYBCallAudioCodecOpus

[CYBCallConfig mediaStreamConfiguration].audioCodec = CYBCallAudioCodecOpus;
CallConfig.mediaStreamConfiguration().audioCodec = .codecOpus


In the latest versions of Firefox and Chrome this codec is used by default for encoding audio streams. This codec is relatively new (released in 2012). It implements lossy audio compression. Opus can be used for both low and high bitrates.

Supported bitrate: constant and variable, from 6 kbit/s to 510 kbit/s Supported sampling rates: from 8 kHz to 48 kHz.

If you develop a Calls application that is supposed to work with high-quality audio, the only choice on audio codecs is OPUS.

OPUS has the best quality, but it also requires a good internet connection.


This codec was developed specially for VoIP applications and streaming audio.

Supported bitrates: adaptive and variable. From 10 kbit/s to 52 kbit/s. Supported sampling rates: 32 kHz.

Good choice for the voice data, but not nearly as good as OPUS.


This audio codec is well-known, it was released in 2004, and became part of the WebRTC project in 2011 when Google acquired Global IP Solutions (the company that developed iLIBC).

When you have very bad channels and low bandwidth, you definitely should try iLBC — it should be strong on such cases.

Supported bitrates: fixed bitrate. 15.2 kbit/s or 13.33 kbit/s Supported sampling rate: 8 kHz.


When you have a strong reliable and good internet connection, then use OPUS.

If you use Calls on 3g networks, use iSAC. If you still have problems, try iLBC.