ApsaraVideo Live:Implement screen sharing on macOS

1. Configure screen sharing encoding parameters

To customize the encoding properties of the screen sharing video stream, call the setScreenShareEncoderConfiguration method. You can configure parameters such as resolution, frame rate, bitrate, Group of Pictures (GOP), and video rotation.

The related configurations are as follows:

Sample code:

/*
  config is a user-defined configuration struct
*/

AliRtcScreenShareEncoderConfiguration * encoderConfig = [[AliRtcScreenShareEncoderConfiguration alloc] init];

encoderConfig.dimensions = CGSizeMake( width_, height_);
encoderConfig.frameRate = frameRate_;   // 5/10/15...
encoderConfig.bitrate = bitrate_;	// 1200...
encoderConfig.rotation = AliRtcRotationMode_0; // 0/90/180/270
encoderConfig.keyFrameInterval = keyFrameInterval_; // 1/2/3 seconds

if (keyFrameInterval_ > 0) {
    encoderConfig.forceStrictKeyFrameInterval = TRUE;
}

encoderConfig.forceStrictKeyFrameInterval = forceStrictKeyFrameInterval_;

[self.mainEngine setScreenShareEncoderConfiguration: encoderConfig];

2. Set up screen sharing preview

To preview the local screen sharing feed, call the setLocalViewConfig method to set the display view for the screen sharing stream (AliEngineVideoTrackScreen).

AliVideoCanvas *canvas = [[AliVideoCanvas alloc]init];
canvas.mirrorMode = _mirrorButton.state == NSControlStateValueOn ? AliRtcRenderMirrorModeAllEnabled:AliRtcRenderMirrorModeAllDisabled;
canvas.view = renderView;
int rv = [self.mainEngine setLocalViewConfig:canvas forTrack:AliRtcVideoTrackScreen];

3. (Remote) View screen sharing

To view the screen sharing feed of a remote user, you can call the setRemoteViewConfig method in the onRemoteTrackAvailableNotify callback to set the display view.

- (void)onRemoteTrackAvailableNotify:(NSString *)uid audioTrack:(AliRtcAudioTrack)audioTrack videoTrack:(AliRtcVideoTrack)videoTrack {
    
    /* Handle UI components on the main thread */
    
    dispatch_async(dispatch_get_main_queue(), ^{
      AliVideoCanvas *canvas = [[AliVideoCanvas alloc]init];
      if ( videoTrack == AliRtcVideoTrackScreen ) {
          canvas.view = self._screenshareView;
          int rv = [self.mainEngine setLocalViewConfig:canvas forTrack:AliRtcVideoTrackScreen]; 
      } else {
          /* Find the view corresponding to this user */
          canvas.view = self.findView(uid);
          int rv = [self.mainEngine setLocalViewConfig:canvas forTrack:AliRtcVideoTrackScreen]; 
      }

    });

}

4. Enumerate all shareable desktops

Call the getScreenShareSourceInfoWithType method to obtain a list of shareable windows and desktops.

A system prompt appears to request permission. If the user denies the permission, all subsequent sharing attempts fail.

_screenInfoArray = [self.engine getScreenShareSourceInfoWithType:AliRtcScreenShareDesktop];

/* Add to list */
if (_screenInfoArray) {
    
    for (AliRtcScreenSourceInfo *info in _screenInfoArray) {
        // Name + ID
        NSString *showString = [NSString stringWithFormat:@"%@+%@",info.sourceName,info.sourceId];
        [_screenListBox addItemWithObjectValue:showString];
    }
    
}

5. Start screen sharing

Call the startScreenShareWithDesktopId method to start screen sharing.

Note You must configure config.isPushStream.

AliRtcScreenShareConfig *config = [[AliRtcScreenShareConfig alloc]init];

/* For region-based sharing */
if ( shareRegion ) {
    
    config.isShareByRegion = TRUE ;
    AliRtcScreenShareRegion *region = [[AliRtcScreenShareRegion alloc]init];
    region.originX = regionRect.origin.x;
    region.originY = regionRect.origin.y;
    region.width = regionRect.size.width;
    region.height = regionRect.size.height;
    
    config.shareRegion = region;
    
} else {
    config.isShareByRegion = FALSE;
}

/* Set to true to push stream immediately; otherwise, set to FALSE
   and call updateScreenShareConfig later */

if ( pushStream ) {
    config.isPushStream = TRUE ;
} else {
    config.isPushStream = FALSE ;
}

/* Set desktop ID from _screenListBox */
int idValue =  [[_screenInfoArray[_screenListBox.indexOfSelectedItem] sourceId] intValue] ;
int r = [self.engine startScreenShareWithDesktopId:idValue config:config];

NSLog(@"startScreenShareWithDesktopId:%d",r);
if ( r != 0 ) {
    // Error handling
} 

6. (Optional) Update configuration

To update the screen sharing configuration, call the updateScreenShareConfig method.

AliRtcScreenShareConfig *config = [[AliRtcScreenShareConfig alloc]init];

/* For region-based sharing */
if ( share_region ) {
    
    config.isShareByRegion = TRUE ;
    AliRtcScreenShareRegion *region = [[AliRtcScreenShareRegion alloc]init];
    region.originX = regionRect.origin.x;
    region.originY = regionRect.origin.y;
    region.width = regionRect.size.width;
    region.height = regionRect.size.height;
    
    config.shareRegion = region;
    
} else {
    config.isShareByRegion = FALSE;
}

/* Set to true to push stream immediately; otherwise, set to FALSE
   and call updateScreenShareConfig later */

if ( pushStream ) {
    config.isPushStream = TRUE ;
} else {
    config.isPushStream = FALSE ;
}
      
[self.engine updateScreenShareConfig:mScreenConfig];

7. Stop screen sharing

[self.engine stopScreenShare];

1. Display all shareable windows

Based on your business requirements, you can call the startScreenShareWithWindowId method to share a specific window.

_windowInfoArray = [self.engine getScreenShareSourceInfoWithType:AliRtcScreenShareWindow];


/* Display in listBox */
if (_windowInfoArray) {
    for (AliRtcScreenSourceInfo *info in _windowInfoArray) {
        // Name + ID
        NSString *showString = [NSString stringWithFormat:@"%@+%@",info.sourceName,info.sourceId];
        [_windowsListBox addItemWithObjectValue:showString];
    }
}

2. Share a specific window

AliRtcScreenShareConfig *config = [[AliRtcScreenShareConfig alloc]init];

/* For region-based sharing */
if ( shareRegion ) {
    
    config.isShareByRegion = TRUE ;
    AliRtcScreenShareRegion *region = [[AliRtcScreenShareRegion alloc]init];
    region.originX = regionRect.origin.x;
    region.originY = regionRect.origin.y;
    region.width = regionRect.size.width;
    region.height = regionRect.size.height;
    
    config.shareRegion = region;
    
} else {
    config.isShareByRegion = FALSE;
}


/* Set to true to push stream immediately; otherwise, set to FALSE.
   Later, call updateScreenShareConfig to modify the push stream flag */

if ( pushStream ) {
    config.isPushStream = TRUE ;
} else {
    config.isPushStream = FALSE ;
}

/* Set window ID from _windowsListBox */

int idValue =  [[_windowInfoArray[_windowsListBox.indexOfSelectedItem] sourceId] intValue] ;
int r = [self.engine startScreenShareWithWindowId:idValue config:config];

NSLog(@"startScreenShareWithWindowId:%d",r);
if ( r != 0 ) {
    // Error handling
} 

3. Stop sharing a window or desktop

Call the stopScreenShare method to stop sharing.

[self.mainEngine stopScreenShare];