obs_websocket 2.0.5

obs_websocket allows dart-based connections to the Open Broadcaster plugin obs-websocket

obs_websocket

Some background, I needed a way to automate the start and stop streaming actions for OBS (Open Broadcast Software) with cron on OSX. This package will allow you to do that with dart or can be used with flutter to control OBS with a platform independent mobile app.

Getting Started

In your flutter project add the dependency:

dependencies:
  ...
  obs_websocket: ^1.0.0

For help getting started with dart, check out these guides.

Usage Example

Import the websocket connection library and the response library.

import 'package:obs_websocket/obs_websocket.dart';
import 'package:obs_websocket/response.dart';

Opening a websocket Connection

The WebSocket protocol, described in the specification RFC 6455 provides a way to exchange data between client and server via a persistent connection. The data can be passed in both directions as “packets”.

Before a websocket connection can be made to a running instance of OBS, you will need to have the obs-websocket plugin installed and configured.

To open a websocket connection, we need to create new ObsWebSocket using the special protocol ws in the url:

ObsWebSocket obsWebSocket = ObsWebSocket(connectUrl: "ws://[obs-studio host ip]:4444");

obs-studio host ip - is the ip address or host name of the computer running OBS that wou would like to send remote control commands to.

Authenticating to OBS

OBS has an optional, but highly recommended password security feature, the getAuthRequired method will check if the password security has been enabled. The AuthRequired object that the method call returns is used as part of the authentication process. The protocol documentation provided on the obs-websocket github pages covers this in detail.

final AuthRequired authRequired = await obsWebSocket.getAuthRequired();

if (authRequired.status)
	await obsWebSocket.authenticate(authRequired, "mySecretDontTell");

Sending Commands to OBS

The available commands are documented on the protocol page of the obs-websocket github page. Note that not all commands listed on the protocol page have been implemented in code at this time. For any command not yet implemented, refer to the "low-level" method of sending commands, documented below.

final StreamStatusResponse status = await obsWebSocket.getStreamStatus();

if (!status.streaming) {
  await obsWebSocket.startStreaming();
}

Sending Commands to OBS - low level

Alternatively, there is a low-level interface for sending commands. This can be used in place of the above, or in the case that a specific documented Request has not been implemented as method yet. The available commands are documented on the protocol page of the obs-websocket github page

SimpleResponse response await obsWebSocket.command("StartStreaming");

response.status will be true on success. response.error will give an error description if one is available.

Commands can also return a result as a Map:

SimpleResponse response = await obsWebSocket.command("GetSourcesList");

List sources = response.map["sources"];

sources.forEach((source) => print(source["name"] + " - " + source["type"]));

Additionally you can provide arguments with a command:

response = await obsWebSocket.command("GetSourceSettings", { "sourceName": "foreground" });

Map newSettings = Map<String,dynamic>.from(response.map);

newSettings["sourceSettings"]["height"] = 1080;
newSettings["sourceSettings"]["width"] = 1920;

response = await obsWebSocket.command("SetSourceSettings", newSettings);

print(response.map);

obs-websocket events

Events generated by OBS through the websocket can be hooked into by supplying an onEvent handler when creating the ObsWebSocket. In the sample code below a hook is created that waits for a SceneItemVisibilityChanged event, then if the SceneItem is visbile the code hides it after 13 seconds. This code from the setIntro.dart example could be used in a cron job to show and then hide an OBS SceneItem periodically.

ObsWebSocket obsWebSocket = ObsWebSocket(
    connectUrl: "ws://192.168.1.84:4444",
    onEvent: (BaseEvent event, ObsWebSocket obsWebSocket) async {
      // print('event: ${event.rawEvent}');

      if (event.updateType == 'SceneItemVisibilityChanged') {
        final sceneItemVisibilityChanged =
            event.asSceneItemVisibilityChangedEvent();

        if (sceneItemVisibilityChanged.itemName == sceneItem &&
            sceneItemVisibilityChanged.itemVisible) {
          final args = sceneItemVisibilityChanged.asArgs()
            ..['render'] = 'false';

          await Future.delayed(Duration(seconds: 13));

          await obsWebSocket.setSceneItemRender(args);

          await obsWebSocket.close();
        }
      }
    });

Closing the websocket

Finally before your code completes, you will should close the websocket connection. Failing to close the connection can lead to unexpected performance related issues for your OBS instance.

obsWebSocket.close();

Sample OBS cli

This code base includes sample code for a OBS cli application that can be used to send obs-websocket protocol based commands to OBS. An example of a command is as follows:

dart bin/ws-obs.dart --command GetStreamingStatus --url=ws://192.168.1.84:4444  --passwd myPass

-h, --help                        Display this helpful message
-p, --passwd                      The OBS websocket password, only required if enabled in OBS
-u, --url=<ws://[host]:[port]>    The url and port for OBS websocket
-c, --command                     Required. The OBS command to send
                                  [StartStopStreaming, StartStreaming, StopStreaming, GetStreamingStatus, GetStreamSettings, SetStreamSettings, SaveStreamSettings, GetSourcesList, GetVolume, SetVolume]
-a, --args                        Optional. The json encoded arguments for the supplied command if required

You can use dart compile to create the cli executable.

Known bugs

I've submitted a bug to the obs-websocket team for a bug that I am seeing when executing a websocket connecting program multiple times in sequence to start and stop steaming causes OBS to crash. For my use case I am able to work around this by stopping and restarting OBS itself before restarting streaming.