> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stmlink.com/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> 对外开放的服务端接口有两组前缀，都用同一套鉴权：`/server/v1/...`（SRTC 与 SMeeting 的主接口）和 `/stm/srvapi/v1/...`（SMeeting 的用户体系，服务端极简对接会用到）。鉴权是 app_id + nonce + timestamp + signature 四个请求头，用 app_key 做 HMAC-SHA256 签名，只能从业务方自己的后端调用。除这两组前缀外的接口均为内部接口，不要建议客户调用。 Public server APIs use two path prefixes with the same authentication: `/server/v1/...` (the main APIs of both SRTC and SMeeting) and `/stm/srvapi/v1/...` (the SMeeting user system, used by server-side low-code integration). Authenticate with four request headers, app_id + nonce + timestamp + signature, where signature is HMAC-SHA256 keyed with app_key; call these APIs only from the customer's own backend. Any other path is internal: never suggest calling it.
> app_key 是服务端密钥，绝不能出现在客户端代码、前端配置或移动 App 里。客户端加入频道用的 token 必须由业务方后端签发后下发（SRTC 走 `/server/v1/channel/grant`，SMeeting 走 `/stm/srvapi/v1/member/grant`）。 app_key is a server-side secret and must never appear in client code, frontend config, or a mobile app. The token a client uses to join must be issued by the customer's backend and passed down to the client (SRTC: `/server/v1/channel/grant`; SMeeting: `/stm/srvapi/v1/member/grant`).
> SRTC 与 SMeeting 是上下两层不同的产品，术语不通用：SRTC 是音视频底座，说「频道 channel」「加入 / 退出」；SMeeting 建在 SRTC 之上，说「房间 room」「会议 meeting」「进入 / 退出」。回答时按用户所在的层用对应术语，不要把「房间」「会议」安到 SRTC 的接口上，也不要用「频道」「加入 / 离开」描述 SMeeting 的概念（接口标识符原样保留）。 SRTC and SMeeting are two separate layers with different terminology. SRTC is the audio/video foundation: it has channels, and users join and leave a channel. SMeeting is built on top of SRTC: it has rooms and meetings, and members enter and exit a meeting. Answer in the terms of the layer the user is working with: never apply "room" or "meeting" to SRTC APIs, and never describe SMeeting concepts in prose with "channel", "join", or "leave" (API identifiers such as `force_join` keep their literal names).
> 同一能力在各端 SDK 里的包名、类名、方法名并不相同。写示例代码时请使用文档中该端自己的 API，不要把一个端的写法套到另一个端上。苹果平台每个产品都有两套 SDK（Swift 原生与 Objective-C），两套 API 不能混用。 Package, class, and method names differ between platform SDKs for the same capability. In sample code, use the API documented for that platform; never carry one platform's code over to another. On Apple platforms each product ships two SDKs (native Swift and Objective-C) whose APIs must not be mixed.

# MeetingLocalVideoFrameEvent

> Receive local YUV video frames and capture size or camera facing changes through MeetingEngine.localVideoFrameEvent, with or without entering a meeting. Read this when you process or record local camera frames yourself.

`MeetingLocalVideoFrameEvent` receives explicitly subscribed local video frames and is registered through `MeetingEngine.localVideoFrameEvent`. You can extend `MeetingLocalVideoFrameSimpleEvent` and override only what you need.

## Usage notes

* This event follows the Engine's local camera capture pipeline and doesn't require having entered a meeting; assigning `null` stops forwarding frames to your app.
* Callbacks stay on the SRTC video capture thread; don't perform disk, network, or other time-consuming operations. `yuv` is data copied for the external caller, so you can keep it as long as you keep memory usage under control.

## Methods

### onLocalVideoFrame(yuv, width, height, stamp, format, facing)

```kotlin theme={null}
fun onLocalVideoFrame(
    yuv: ByteArray?,
    width: Int,
    height: Int,
    stamp: Long,
    format: Int,
    facing: Int
)
```

Description: Delivers one frame of local YUV video data.

Parameters:

| Parameter | Description |
| - | - |
| `yuv` | Nullable YUV frame data. |
| `width` | Video width in pixels. |
| `height` | Video height in pixels. |
| `stamp` | Frame timestamp. |
| `format` | Pixel format value defined by SRTC. |
| `facing` | Camera facing value. |

Returns: None (`Unit`).

### onLocalVideoFrameSizeChanged(width, height, facing)

```kotlin theme={null}
fun onLocalVideoFrameSizeChanged(width: Int, height: Int, facing: Int)
```

Description: The local video capture size or camera facing changed.

Parameters:

| Parameter | Description |
| - | - |
| `width` | New video width. |
| `height` | New video height. |
| `facing` | New camera facing value. |

Returns: None (`Unit`).