tencent cloud

Application Scenarios

TRTC supports four room entry modes. Video call (VideoCall) and audio call (VoiceCall) are the call modes, and interactive video streaming (Live) and interactive audio streaming (VoiceChatRoom) are the live streaming modes.
The live streaming modes allow a maximum of 100,000 concurrent users in each room with smooth mic on/off. Co-anchoring latency is kept below 300 ms and watch latency below 1,000 ms. The live streaming modes are suitable for use cases such as low-latency interactive live streaming, interactive classrooms for up to 100,000 participants, video dating, online education, remote training, and mega-scale conferencing.

How It Works

TRTC services use two types of server nodes: access servers and proxy servers.

• Access server
  This type of nodes use high-quality lines and high-performance servers and are better suited to drive low-latency end-to-end calls.
• Proxy server
  This type of servers use mediocre lines and average-performance servers and are better suited to power high-concurrency stream pulling and playback.

In the live streaming modes, TRTC has introduced the concept of "role". Users are either in the role of "anchor" or "audience". Anchors are assigned to access servers, and audience to proxy servers. Each room allows up to 100,000 users in the role of audience.
For audience to speak, they must switch the role (switchRole) to “anchor”. The switching process involves users being migrated from proxy servers to access servers. TRTC’s low-latency streaming and smooth mic on/off technologies help keep this process short.

Sample Code

You can visit GitHub to obtain the sample code used in this document.

Note：

If your access to GitHub is slow, download the ZIP file here.

Directions

Step 1. Integrate the SDKs

You can integrate the TRTC SDK into your project in the following ways:

Method 1: integrating through CocoaPods

1. Install CocoaPods. For detailed directions, please see Getting Started.

2. Open the Podfile file in the root directory of your project and add the code below.

   Note：

   If you cannot find a Podfile file in the directory, run the pod init command to create one and add the code below.

   target 'Your Project' do
       pod 'TXLiteAVSDK_TRTC'
   end
   

3. Run the command below to install the TRTC SDK.

   pod install
   

After successful installation, an XCWORKSPACE file will be generated in the root directory of your project.
4. Open the XCWORKSPACE file.

Method 2: manual integration

If you do not want to install CocoaPods, or your access to CocoaPods repositories is slow, you can download the ZIP file of the SDK and integrate it into your project as instructed in SDK Quick Integration > iOS.

Step 2. Add device permission requests

Add camera and mic permission requests in the Info.plist file.

Step 3. Initialize an SDK instance and configure event callbacks

1. Call the sharedInstance() API to create a TRTCCloud instance.
   // Create a `TRTCCloud` instance
   _trtcCloud = [TRTCCloud sharedInstance];
   _trtcCloud.delegate = self;

2. Set the attributes of delegate to subscribe to event callbacks and listen for event and error notifications.
   // Error events must be listened for and captured, and error messages should be sent to users.
   - (void)onError:(TXLiteAVError)errCode errMsg:(NSString *)errMsg extInfo:(NSDictionary *)extInfo {
       if (ERR_ROOM_ENTER_FAIL == errCode) {
           [self toastTip:@"Failed to enter room"];
           [self.trtcCloud exitRoom];
       }
   }

Step 4. Assemble the room entry parameter TRTCParams

When calling the enterRoom() API, you need to pass in a key parameter TRTCParams, which includes the following required fields:

Note：

• In TRTC, users with the same userId cannot be in the same room at the same time as it will cause a conflict.

• The value of appScene must be the same on each client. Inconsistent appScene may cause unexpected problems.

Step 5. Enable camera preview and mic capturing

1. Call startLocalPreview() to enable preview of the local camera. The SDK will ask for camera permission.
2. Call setLocalViewFillMode() to set the display mode of the local video image:

• Fill: aspect fill. The image may be scaled up and cropped, but there are no black bars.
• Fit: aspect fit. The image may be scaled down to ensure that it’s displayed in its entirety, and there may be black bars.

3. Call setVideoEncoderParam() to set the encoding parameters for the local video, which determine the quality of your video seen by other users in the room.
4. Call startLocalAudio() to turn the mic on. The SDK will ask for mic permission.

// Sample code: publish the local audio/video stream
[self.trtcCloud startLocalPreview:_isFrontCamera view:self.view];

// Set local video encoding parameters
TRTCVideoEncParam *encParams = [TRTCVideoEncParam new];
encParams.videoResolution = TRTCVideoResolution_640_360;
encParams.videoBitrate = 550;
encParams.videoFps = 15;
    
[self.trtcCloud setVideoEncoderParam:encParams];

Step 6. Set beauty filters

1. Call getBeautyManager() to get the beauty filter management class TXBeautyManager.
2. Call setBeautyStyle() to set the beauty filter style.

• Smooth: smooth. This style features more obvious skin smoothing effect and is typically used by influencers.
• Nature: natural. This style retains more facial details and is more natural.
• Pitu: this style is supported only in the Professional Edition.

3. Call setBeautyLevel() to set the skin smoothing strength (5 is recommended).
4. Call setWhitenessLevel() to set the skin brightening strength (5 is recommended).
5. Given the yellow tint of the iPhone camera, we recommended that you call setFilter() to apply the skin brightening filter to your video. You can download the file for the filter here.

Step 7. Create a room and push streams

1. Set the role field in TRTCParams to TRTCRoleType.anchor to take the role of “anchor”.
2. Call enterRoom(), specifying appScene, and a room whose ID is the value of the roomId field in TRTCParams will be created.

• TRTCAppScene.LIVE: the interactive video streaming mode, which is used in the example of this document
• TRTCAppScene.voiceChatRoom: the interactive audio streaming mode

3. After the room is created, start encoding and transferring audio/video data. The SDK will return the onEnterRoom(result) callback. If result is greater than 0, room entry succeeds, and the value indicates the time (ms) room entry takes; if result is less than 0, room entry fails, and the value is the error code for the failure.

- (void)enterRoom() {
    TRTCParams *params = [TRTCParams new];
    params.sdkAppId = SDKAppID;
    params.roomId = _roomId;
    params.userId = _userId;
    params.role = TRTCRoleAnchor;
    params.userSig = [GenerateTestUserSig genTestUserSig:params.userId];
    [self.trtcCloud enterRoom:params appScene:TRTCAppSceneLIVE];
}

- (void)onEnterRoom:(NSInteger)result {
    if (result > 0) {
        [self toastTip:@"Entered room successfully"];
    } else {
        [self toastTip:@"Failed to enter room"];
    }
}

Step 8. Enter the room as audience

1. Set the role field in TRTCParams to TRTCRoleType.audience to take the role of “audience”.
2. Call enterRoom() to enter the room whose ID is the value of the roomId field in TRTCParams, specifying appScene.

• TRTCAppScene.LIVE: the interactive video streaming mode, which is used in the example of this document
• TRTCAppScene.voiceChatRoom: the interactive audio streaming mode

3. Watch the anchor’s video:

• If you know the anchor’s userId, call startRemoteView(userId, view: view) with the anchor’s userId passed in to play the anchor's video.
• If you do not know the anchor’s userId, find the anchor’s userId in the onUserVideoAvailable() callback, which you will receive after room entry, and call startRemoteView(userId, view: view) with the anchor’s userId passed in to play the anchor’s video.

Step 9. Co-anchor

1. Call switch(TRTCRoleType.TRTCRoleAnchor) to switch the role to “anchor” (TRTCRoleType.TRTCRoleAnchor).
2. Call startLocalPreview() to enable preview of the local image.
3. Call startLocalAudio() to enable mic capturing.

// Sample code: start co-anchoring
[self.trtcCloud switchRole:TRTCRoleAnchor];
[self.trtcCloud startLocalAudio:TRTCAudioQualityMusic];
[self.trtcCloud startLocalPreview:_isFrontCamera view:self.view];

// Sample code: end co-anchoring
[self.trtcCloud switchRole:TRTCRoleAudience];
[self.trtcCloud stopLocalAudio];
[self.trtcCloud stopLocalPreview]

Step 10. Compete across rooms

Anchors from two rooms can compete with each other without exiting their current rooms.

1. Anchor A calls the connectOtherRoom() API. The API uses parameters in JSON strings, so anchor A needs to pass the roomId and userId of anchor B in the format of {"roomId": 978,"userId": "userB"} to the API.
2. After the cross-room call is set up, anchor A will receive the onConnectOtherRoom() callback, and all users in both rooms will receive the onUserVideoAvailable() and onUserAudioAvailable() callbacks.
   For example, after anchor A in room "001" uses connectOtherRoom() to call anchor B in room “002” successfully all users in room "001" will receive the onUserVideoAvailable(B, available: true) and onUserAudioAvailable(B, available: true) callbacks, and all users in room "002" will receive the onUserVideoAvailable(A, available: true) and onUserAudioAvailable(A, available: true) callbacks.
3. Users in both rooms can call startRemoteView(userId, view: view) to play the video of the anchor in the other room, and audio will be played back automatically.

// Sample code: cross-room competition
NSMutableDictionary * jsonDict = [[NSMutableDictionary alloc] init];
[jsonDict setObject:@([_otherRoomIdTextField.text intValue]) forKey:@"roomId"];
[jsonDict setObject:_otherUserIdTextField.text forKey:@"userId"];
NSData* jsonData = [NSJSONSerialization dataWithJSONObject:jsonDict options:NSJSONWritingPrettyPrinted error:nil];
NSString* jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
[self.trtcCloud connectOtherRoom:jsonString];

Step 11. Exit the room

Call exitRoom() to exit the room. The SDK disables and releases devices such as cameras and mics during room exit. Therefore, room exit is not an instant process. It completes only after the onExitRoom() callback is received.

// Please wait for the `onExitRoom` callback after calling the room exit API.
[self.trtcCloud exitRoom];

- (void)onExitRoom:(NSInteger)reason {
    NSLog(@"Exited room: reason: %ld", reason)
}

Note：

If your application integrates multiple audio/video SDKs, please wait after you receive the onExitRoom callback to start other SDKs; otherwise, the device busy error may occur.