> ## 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.

# RemoteVideoTrack

> Android remote video track API: bind render views, monitor receive stalls with RTCRemoteVideoEvent, and configure the VcsPlayerGlTextureView / VcsPlayerGlSurfaceView render views (rotation, flip, scale type, updateFrame). Read when displaying remote or local video on Android.

## Description

`RemoteVideoTrack` renders remote video and monitors the status of the remote stream.

## RemoteVideoTrack methods

### setRemoteVideoEvent(event)

```kotlin theme={null}
fun setRemoteVideoEvent(event: RTCRemoteVideoEvent)
```

Description: Sets the remote video stream status listener and registers the global clock check.\
Parameters:

* `event`: `RTCRemoteVideoEvent`, the remote stream status event callback implementation.
  Returns: None (`Unit`).

When the status is reported:

* If no valid frame is received for about 3 consecutive seconds after subscribing, the callback reports `isChoke = true`.
* When valid frames resume, the callback reports `isChoke = false`.

### removeRemoteVideoEvent()

```kotlin theme={null}
fun removeRemoteVideoEvent()
```

Description: Removes the remote stream status listener and cancels the global clock check.\
Parameters: None.\
Returns: None (`Unit`).

## Rendering methods inherited from VideoTrack

### addPlayView(view)

```kotlin theme={null}
fun addPlayView(view: View): Boolean
```

Description: Adds a single render view. Only `VcsPlayerGlTextureView` / `VcsPlayerGlSurfaceView` are supported.\
Parameters:

* `view`: `View`, the render view.
  Returns: `Boolean`; `true` if the view was added, `false` if the type is unsupported or the view was already added.

### replacePlayView(views)

```kotlin theme={null}
fun replacePlayView(views: MutableList<View>)
```

Description: Replaces the entire list of render views.\
Parameters:

* `views`: `MutableList<View>`, the render views; only `VcsPlayerGlTextureView` / `VcsPlayerGlSurfaceView` are supported.
  Returns: None (`Unit`).

### removePlayView(view)

```kotlin theme={null}
fun removePlayView(view: View)
```

Description: Removes the specified render view.\
Parameters:

* `view`: `View`, the target render view.
  Returns: None (`Unit`).

### removeAllPlayView()

```kotlin theme={null}
fun removeAllPlayView()
```

Description: Removes all render views.\
Parameters: None.\
Returns: None (`Unit`).

## RTCRemoteVideoEvent callback interface

`RTCRemoteVideoEvent` is the remote video stream status callback interface, registered through `setRemoteVideoEvent(event)`.

### onReceiveStreamStatusChange(channel, uid, trackDesc, isChoke)

```kotlin theme={null}
fun onReceiveStreamStatusChange(
    channel: String,
    uid: String,
    trackDesc: String,
    isChoke: Boolean
)
```

Description: Called when the status of a remote video stream changes.\
Parameters:

* `channel`: `String`, the ID of the channel the remote stream belongs to.
* `uid`: `String`, the remote user ID.
* `trackDesc`: `String`, the track description.
* `isChoke`: `Boolean`, whether the stream is stalled; `true` means stalled, `false` means back to normal.
  Returns: None (`Unit`).

## Video render views

Display video with the SDK's `VcsPlayerGlTextureView` or `VcsPlayerGlSurfaceView`. The following usage applies to both remote video and local camera preview:

```kotlin theme={null}
import cn.seastart.rtc.media.original.render.VcsPlayerGlTextureView
import cn.seastart.rtc.media.original.render.VcsPlayerGlSurfaceView
import cn.seastart.rtc.media.original.render.RenderConstants

val view = VcsPlayerGlTextureView(context)
view.setViewScaleType(RenderConstants.CENTERINSIDE)
remoteTrack.addPlayView(view)
```

XML example:

```xml theme={null}
<cn.seastart.rtc.media.original.render.VcsPlayerGlTextureView
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
```

Call the view's `onResume()` / `onPause()` along with the screen lifecycle. When a view is no longer needed, remove it from the track first, then call `onDestroy()` to release render resources. Don't reuse a destroyed view. The track feeds frames to the view, so you don't need to call `updateFrame` yourself for normal subscriptions or camera preview.

### Display configuration

The following methods are available on both views and all return `Unit`:

```kotlin theme={null}
fun customDisplayCtrl(use: Boolean)
fun setViewRotate(rotateAngle: Int)
fun setViewflip(flipX: Boolean, flipY: Boolean)
fun setViewScaleType(ScaleType: Int)
```

| Parameter | Type | Required | Description |
| - | - | - | - |
| `use` | Boolean | Yes | Defaults to `false`, which uses the frame's own orientation and the SDK's preview mirroring configuration; `true` uses this view's custom rotation and flip. |
| `rotateAngle` | Int | Yes | Custom display angle; positive values are counterclockwise. Pass `0/90/180/270` or an equivalent value that differs by full turns. It overrides the frame orientation instead of adding to it; defaults to `0`. |
| `flipX` / `flipY` | Boolean | Yes | Horizontal / vertical flip along the display coordinates in custom mode; both default to `false`, and the default front-camera mirroring isn't applied on top. |
| `ScaleType` | Int | Yes | One of the `RenderConstants` scale constants in the table below; can be set in both normal and custom mode; defaults to `CENTERINSIDE`. |

Rotation, flip, and mode changes take effect from the **next frame**; if no new frame arrives, the displayed frame doesn't change. The scale type can apply to the current frame. The configuration belongs only to this view and doesn't change the video sent to remote users.

| Scale constant | Value | Effect |
| - | - | - |
| `FITXY` | 0 | Stretches to fill the view; the aspect ratio may change. |
| `CENTERCROP` | 1 | Fills the view proportionally and crops from the center. |
| `CENTERINSIDE` | 2 | Shows the full frame proportionally and centered; may leave margins. |
| `FITSTART` | 3 | Shows the full frame proportionally, aligned left / top along the margin direction. |
| `FITEND` | 4 | Shows the full frame proportionally, aligned right / bottom along the margin direction. |

### updateFrame(y, u, v, width, height, format, rotationDegrees)

Use this only when your app submits raw frames directly to a render view:

```kotlin theme={null}
fun updateFrame(
    y: ByteArray?, u: ByteArray?, v: ByteArray?,
    width: Int, height: Int, format: Int, rotationDegrees: Int
)
```

| Parameter | Type | Required | Description |
| - | - | - | - |
| `y` | ByteArray | Yes | Tightly packed Y plane, at least `width × height` bytes. |
| `u` | ByteArray | Yes | For I420, the U plane, at least `width × height / 4` bytes; for NV12 / NV21, the interleaved UV / VU plane, at least `width × height / 2` bytes. |
| `v` | ByteArray? | Required for I420 | For I420, the V plane, at least `width × height / 4` bytes; can be `null` for NV12 / NV21. |
| `width` / `height` | Int | Yes | Original pixel width and height, both positive even numbers; don't pass the rotated dimensions. Row-end padding isn't supported. |
| `format` | Int | Yes | `YuvFormat.I420`, `NV12`, or `NV21`; for the full constants, see [Types](/en/rtc/android/types). |
| `rotationDegrees` | Int | Yes | The **clockwise** rotation still to be applied to the pixels: `0/90/180/270` or an equivalent value that differs by full turns. |

Returns: `Unit`. Frame data is copied before the method returns, after which the app can reuse the arrays. An invalid size, data length, pixel format, or an angle that isn't a multiple of 90 degrees causes the frame to be rejected and the previous frame to be kept; there's no separate failure callback. Custom mode overrides the frame orientation, but the frame angle you pass must still be valid.