# obs-websocket 5.0.0 protocol reference ## General Introduction obs-websocket provides a feature-rich RPC communication protocol, giving access to much of OBS's feature set. This document contains everything you should know in order to make a connection and use obs-websocket's functionality to the fullest. ### Design Goals - Abstraction of identification, events, requests, and batch requests into dedicated message types - Conformity of request naming using similar terms like `Get`, `Set`, `Get[x]List`, `Start[x]`, `Toggle[x]` - Conformity of OBS data key names like `sourceName`, `sourceKind`, `sourceType`, `sceneName`, `sceneItemName` - Error code response system - integer corrosponds to type of error, with optional comment - Possible support for multiple message encoding options: JSON and MessagePack - PubSub system - Allow clients to specify which events they do or don't want to receive from OBS - RPC versioning - Client and server negotiate the latest version of the obs-websocket protocol to communicate with. ## Table of Contents - [Connecting to obs-websocket](#connecting-to-obs-websocket) - [Connection steps](#connection-steps) - [Creating an authentication string](#creating-an-authentication-string) - [Enumerations](#enumerations) - [Base message types](#message-types) - [OpCode 0 Hello](#hello-opcode-0) - [OpCode 1 Identify](#identify-opcode-1) - [OpCode 2 Identified](#identified-opcode-2) - [OpCode 3 Reidentify](#reidentify-opcode-3) - [OpCode 5 Event](#event-opcode-5) - [OpCode 6 Request](#request-opcode-6) - [OpCode 7 RequestResponse](#requestresponse-opcode-7) - [OpCode 8 RequestBatch](#requestbatch-opcode-8) - [OpCode 9 RequestBatchResponse](#requestbatchresponse-opcode-9) - [Events](#events) - [Requests](#requests) ## Connecting to obs-websocket Here's info on how to connect to obs-websocket --- ### Connection steps These steps should be followed precisely. Failure to connect to the server as instructed will likely result in your client being treated in an undefined way. - Initial HTTP request made to the obs-websocket server. - The `Sec-WebSocket-Protocol` header can be used to tell obs-websocket which kind of message encoding to use. By default, obs-websocket uses JSON over text. Available subprotocols: - `obswebsocket.json` - JSON over text frames - `obswebsocket.msgpack` - MsgPack over binary frames - Once the connection is upgraded, the websocket server will immediately send an [OpCode 0 `Hello`](#hello-opcode-0) message to the client. - The client listens for the `Hello` and responds with an [OpCode 1 `Identify`](#identify-opcode-1) containing all appropriate session parameters. - If there is an `authentication` key in the `messageData` object, the server requires authentication, and the steps in [Creating an authentication string](#creating-an-authentication-string) should be followed. - If there is no `authentication` key, the resulting `Identify` object sent to the server does not require an `authentication` string. - The client determines if the server's `rpcVersion` is supported, and if not it provides its closest supported version in `Identify`. - The server receives and processes the `Identify` sent by the client. - If authentication is required and the `Identify` message data does not contain an `authentication` string, or the string is not correct, the connection is closed with [`WebSocketCloseCode::AuthenticationFailed`](#websocketclosecode-enum) - If the client has requested an `rpcVersion` which the server cannot use, the connection is closed with [`WebSocketCloseCode::UnsupportedRpcVersion`](#websocketclosecode-enum). This system allows both the server and client to have seamless backwards compatability. - If any other parameters are malformed (invalid type, etc), the connection is closed with an appropriate close code. - Once identification is processed on the server, the server responds to the client with an [OpCode 2 `Identified`](#identified-opcode-2). - The client will begin receiving events from obs-websocket and may now make requests to obs-websocket. - At any time after a client has been identified, it may send an [OpCode 3 `Reidentify`](#reidentify-opcode-3) message to update certain allowed session parameters. The server will respond in the same way it does during initial identification. #### Connection Notes - If a binary frame is received when using the `obswebsocket.json` (default) subprotocol, or a text frame is received while using the `obswebsocket.msgpack` subprotocol, the connection is closed with [`WebSocketCloseCode::MessageDecodeError`](#websocketclosecode-enum). - The obs-websocket server listens for any messages containing a `request-type` key in the first level JSON from unidentified clients. If a message matches, the connection is closed with [`WebSocketCloseCode::UnsupportedRpcVersion`](#websocketclosecode-enum) and a warning is logged. - If a message with a `messageType` is not recognized to the obs-websocket server, the connection is closed with [`WebSocketCloseCode::UnknownOpCode`](#websocketclosecode-enum). - At no point may the client send any message other than a single `Identify` before it has received an `Identified`. Doing so will result in the connection being closed with [`WebSocketCloseCode::NotIdentified`](#websocketclosecode-enum). --- ### Creating an authentication string obs-websocket uses SHA256 to transmit authentication credentials. The server starts by sending an object in the `authentication` key of its `Hello` message data. The client processes the authentication challenge and responds via the `authentication` string in the `Identify` message data. For this guide, we'll be using `supersecretpassword` as the password. The `authentication` object in `Hello` looks like this (example): ```json { "challenge": "+IxH4CnCiqpX1rM9scsNynZzbOe4KhDeYcTNS3PDaeY=", "salt": "lM1GncleQOaCu9lT1yeUZhFYnqhsLLP1G5lAGo3ixaI=" } ``` To generate the authentication string, follow these steps: - Concatenate the websocket password with the `salt` provided by the server (`password + salt`) - Generate an SHA256 binary hash of the result and base64 encode it, known as a base64 secret. - Concatenate the base64 secret with the `challenge` sent by the server (`base64_secret + challenge`) - Generate a binary SHA256 hash of that result and base64 encode it. You now have your `authentication` string. For real-world examples of the `authentication` string creation, refer to the obs-websocket client libraries listed on the [README](README.md). --- ### Enumerations These are the enumeration definitions for various codes used by obs-websocket. #### WebSocketOpCode Enum ```cpp enum WebSocketOpCode { Hello = 0, Identify = 1, Identified = 2, Reidentify = 3, Event = 5, Request = 6, RequestResponse = 7, RequestBatch = 8, RequestBatchResponse = 9, }; ``` #### WebSocketCloseCode Enum ```cpp enum WebSocketCloseCode { // Internal only DontClose = 0, // Reserved UnknownReason = 4000, // The server was unable to decode the incoming websocket message MessageDecodeError = 4002, // A data key is missing but required MissingDataKey = 4003, // A data key has an invalid type InvalidDataKeyType = 4004, // The specified `op` was invalid or missing UnknownOpCode = 4005, // The client sent a websocket message without first sending `Identify` message NotIdentified = 4006, // The client sent an `Identify` message while already identified AlreadyIdentified = 4007, // The authentication attempt (via `Identify`) failed AuthenticationFailed = 4008, // The server detected the usage of an old version of the obs-websocket protocol. UnsupportedRpcVersion = 4009, // The websocket session has been invalidated by the obs-websocket server. SessionInvalidated = 4010, }; ``` #### EventSubscriptions Enum ```cpp enum EventSubscription { // Set subscriptions to 0 to disable all events None = 0, // Receive events in the `General` category General = (1 << 0), // Receive events in the `Config` category Config = (1 << 1), // Receive events in the `Scenes` category Scenes = (1 << 2), // Receive events in the `Inputs` category Inputs = (1 << 3), // Receive events in the `Transitions` category Transitions = (1 << 4), // Receive events in the `Filters` category Filters = (1 << 5), // Receive events in the `Outputs` category Outputs = (1 << 6), // Receive events in the `Scene Items` category SceneItems = (1 << 7), // Receive events in the `MediaInputs` category MediaInputs = (1 << 8), // Receive all event categories All = (General | Config | Scenes | Inputs | Transitions | Filters | Outputs | SceneItems | MediaInputs), // InputVolumeMeters event (high-volume) InputVolumeMeters = (1 << 9), // InputActiveStateChanged event (high-volume) InputActiveStateChanged = (1 << 10), // InputShowStateChanged event (high-volume) InputShowStateChanged = (1 << 11), }; ``` Subscriptions are a bitmask system. In many languages, to generate a bitmask that subscribes to `General` and `Scenes`, you would do: `subscriptions = ((1 << 0) | (1 << 2))` #### RequestStatus Enum ```cpp enum RequestStatus { Unknown = 0, // For internal use to signify a successful parameter check NoError = 10, Success = 100, // The `requestType` field is missing from the request data MissingRequestType = 203, // The request type is invalid or does not exist UnknownRequestType = 204, // Generic error code (comment required) GenericError = 205, // A required request parameter is missing MissingRequestParameter = 300, // The request does not have a valid requestData object. MissingRequestData = 301, // Generic invalid request parameter message (comment required) InvalidRequestParameter = 400, // A request parameter has the wrong data type InvalidRequestParameterType = 401, // A request parameter (float or int) is out of valid range RequestParameterOutOfRange = 402, // A request parameter (string or array) is empty and cannot be RequestParameterEmpty = 403, // There are too many request parameters (eg. a request takes two optionals, where only one is allowed at a time) TooManyRequestParameters = 404, // An output is running and cannot be in order to perform the request (generic) OutputRunning = 500, // An output is not running and should be OutputNotRunning = 501, // An output is paused and should not be OutputPaused = 502, // An output is disabled and should not be OutputDisabled = 503, // Studio mode is active and cannot be StudioModeActive = 504, // Studio mode is not active and should be StudioModeNotActive = 505, // The resource was not found ResourceNotFound = 600, // The resource already exists ResourceAlreadyExists = 601, // The type of resource found is invalid InvalidResourceType = 602, // There are not enough instances of the resource in order to perform the request NotEnoughResources = 603, // The state of the resource is invalid. For example, if the resource is blocked from being accessed InvalidResourceState = 604, // The specified input (obs_source_t-OBS_SOURCE_TYPE_INPUT) had the wrong kind InvalidInputKind = 605, // Creating the resource failed ResourceCreationFailed = 700, // Performing an action on the resource failed ResourceActionFailed = 701, // Processing the request failed unexpectedly (comment required) RequestProcessingFailed = 702, // The combination of request parameters cannot be used to perform an action CannotAct = 703, }; ``` ## Message Types (OpCodes) The following message types are the low-level message types which may be sent to and from obs-websocket. Messages sent from the obs-websocket server or client may contain these first-level keys, known as the base object: ``` { "op": number, "d": object } ``` - `op` is a [`WebSocketOpCode` OpCode.](#websocketopcode-enum) - `d` is an object of the data keys associated with the operation. --- ### Hello (OpCode 0) - Sent from: obs-websocket - Sent to: Freshly connected websocket client - Description: First message sent from the server immediately on client connection. Contains authentication information if auth is required. Also contains RPC version for version negotiation. **Data Keys:** ``` { "obsWebSocketVersion": string, "rpcVersion": number, "authentication": object(optional) } ``` - `rpcVersion` is a version number which gets incremented on each **breaking change** to the obs-websocket protocol. Its usage in this context is to provide the current rpc version that the server would like to use. **Example Messages:** Authentication is required ```json { "op": 0, "d": { "obsWebSocketVersion": "5.0.0", "rpcVersion": 1, "authentication": { "challenge": "+IxH4CnCiqpX1rM9scsNynZzbOe4KhDeYcTNS3PDaeY=", "salt": "lM1GncleQOaCu9lT1yeUZhFYnqhsLLP1G5lAGo3ixaI=" } } } ``` Authentication is not required ```json { "op": 0, "d": { "obsWebSocketVersion": "5.0.0", "rpcVersion": 1 } } ``` --- ### Identify (OpCode 1) - Sent from: Freshly connected websocket client - Sent to: obs-websocket - Description: Response to `Hello` message, should contain authentication string if authentication is required, along with PubSub subscriptions and other session parameters. **Data Keys:** ``` { "rpcVersion": number, "authentication": string(optional), "ignoreInvalidMessages": bool(optional) = false, "eventSubscriptions": number(optional) = (EventSubscription::All) } ``` - `rpcVersion` is the version number that the client would like the obs-websocket server to use. - When `ignoreInvalidMessages` is true, the socket will not be closed for [`WebSocketCloseCode`](#websocketclosecode-enum): `MessageDecodeError`, `UnknownOpCode`, or `MissingDataKey`. Instead, the message will be logged and ignored. - `eventSubscriptions` is a bitmask of [`EventSubscriptions`](#eventsubscriptions-enum) items to subscribe to events and event categories at will. By default, all event categories are subscribed, except for events marked as high volume. High volume events must be explicitly subscribed to. **Example Message:** ```json { "op": 1, "d": { "rpcVersion": 1, "authentication": "Dj6cLS+jrNA0HpCArRg0Z/Fc+YHdt2FQfAvgD1mip6Y=", "eventSubscriptions": 33 } } ``` --- ### Identified (OpCode 2) - Sent from: obs-websocket - Sent to: Freshly identified client - Description: The identify request was received and validated, and the connection is now ready for normal operation. **Data Keys:** ``` { "negotiatedRpcVersion": number } ``` - If rpc version negotiation succeeds, the server determines the RPC version to be used and gives it to the client as `negotiatedRpcVersion` **Example Message:** ```json { "op": 2, "d": { "negotiatedRpcVersion": 1 } } ``` --- ### Reidentify (OpCode 3) - Sent from: Identified client - Sent to: obs-websocket - Description: Sent at any time after initial identification to update the provided session parameters. **Data Keys:** ``` { "ignoreInvalidMessages": bool(optional) = false, "eventSubscriptions": number(optional) = (EventSubscription::All) } ``` - Only the listed parameters may be changed after initial identification. To change a parameter not listed, you must reconnect to the obs-websocket server. --- ### Event (OpCode 5) - Sent from: obs-websocket - Sent to: All subscribed and identified clients - Description: An event coming from OBS has occured. Eg scene switched, source muted. **Data Keys:** ``` { "eventType": string, "eventIntent": number, "eventData": object(optional) } ``` - `eventIntent` is the original intent required to be subscribed to in order to receive the event. **Example Message:** ```json { "op": 2, "d": { "eventType": "StudioModeStateChanged", "eventIntent": 1, "eventData": { "studioModeEnabled": true } } } ``` --- ### Request (OpCode 6) - Sent from: Identified client - Sent to: obs-websocket - Description: Client is making a request to obs-websocket. Eg get current scene, create source. **Data Keys:** ``` { "requestType": string, "requestId": string, "requestData": object(optional), } ``` **Example Message:** ```json { "op": 6, "d": { "requestType": "SetCurrentScene", "requestId": "f819dcf0-89cc-11eb-8f0e-382c4ac93b9c", "requestData": { "sceneName": "Scene 12" } } } ``` --- ### RequestResponse (OpCode 7) - Sent from: obs-websocket - Sent to: Identified client which made the request - Description: obs-websocket is responding to a request coming from a client. **Data Keys:** ``` { "requestType": string, "requestId": string, "requestStatus": object, "responseData": object(optional) } ``` - The `requestType` and `requestId` are simply mirrors of what was sent by the client. `requestStatus` object: ``` { "result": bool, "code": number, "comment": string(optional) } ``` - `result` is `true` if the request resulted in [`RequestStatus::Success`](#requeststatus-enum). False if otherwise. - `code` is a [`RequestStatus`](#requeststatus-enum) code. - `comment` may be provided by the server on errors to offer further details on why a request failed. **Example Messages:** Successful Response ```json { "op": 7, "d": { "requestType": "SetCurrentScene", "requestId": "f819dcf0-89cc-11eb-8f0e-382c4ac93b9c", "requestStatus": { "result": true, "code": 100 } } } ``` Failure Response ```json { "op": 7, "d": { "requestType": "SetCurrentScene", "requestId": "f819dcf0-89cc-11eb-8f0e-382c4ac93b9c", "requestStatus": { "result": false, "code": 608, "comment": "Parameter: sceneName" } } } ``` --- ### RequestBatch (OpCode 8) - Sent from: Identified client - Sent to: obs-websocket - Description: Client is making a batch of requests for obs-websocket. Requests are processed serially (in order) by the server. **Data Keys:** ``` { "requestId": string, "haltOnFailure": bool(optional) = false, "requests": array