# startPublishing method Null safety

Future<void> startPublishing(

1. String streamId,
2. int streamType

)

Start pushing to Tencent Cloud CSS CDN

This API specifies the `StreamId` corresponding to the current user's audio/video stream in Tencent Cloud CDN and thus specify the current user's CDN playback address.

For example, if you use the following code to set the `StreamId` of the current user's primary image to `user_stream_001`, then the CDN playback address corresponding to the user's primary image is: `http://yourdomain/live/user_stream_001.flv`, where `yourdomain` is your playback domain name with an ICP filing. You can configure your playback domain name in the CSS console. Tencent Cloud doesn't provide a default playback domain name.

You can also specify the `streamId` when setting the `TRTCParams` parameter of `enterRoom`, which is the recommended approach.

Parameters:

streamId Custom stream ID.

streamType Only `TRTCCloudDef.TRTC_VIDEO_STREAM_TYPE_BIG` and `TRTCCloudDef.TRTC_VIDEO_STREAM_TYPE_SUB` are supported.

Note:

You need to enable the "Enable Relayed Push" option on the "Function Configuration" page in the TRTC console first.

*If you select "Specified stream for relayed push", you can use this API to push the corresponding audio/video stream to Tencent Cloud CDN and specify the entered stream ID.

*If you select "Global auto-relayed push", you can use this API to adjust the default stream ID.

## Implementation

    Future<void> startPublishing(String streamId, int streamType) {
      return _channel.invokeMethod('startPublishing', {
        "streamId": streamId,
        "streamType": streamType,
      });
    }