# Raw video with alpha channel

<!-- WARNING: THIS FILE WAS AUTOGENERATED! DO NOT EDIT! -->

Session hosts who hold a raw streaming token can enable alpha channel mode, which requests that Zoom's Video SDK send both the original video data and an alpha mask demarking the edge of a user's body. The Video SDK can then use the alpha mask and raw data to remove the user's background and render session users natively in the host's virtual world.

## Turn on alpha channel mode

Before turning on the alpha channel, call the following:

-   `canEnableAlphaChannelMode` to check whether the alpha channel mode is already turned on
-   `isDeviceSupportAlphaChannelMode` to check whether the device hardware capabilities are capable of supporting video alpha mode

To turn on, or off, the alpha channel, call `enableAlphaChannelMode`.

```swift
let videoHelper = ZMVideoSDK.shared().getVideoHelper()
if videoHelper.canEnableAlphaChannelMode()  {
    videoHelper.isDeviceSupportAlphaChannelMode() // Determines whether the device hardware capabilities are capable of supporting video alpha mode.
    videoHelper.enableAlphaChannelMode(true) // TRUE/FALSE to enable/disable alpha channel.
    videoHelper.isAlphaChannelModeEnabled()
}
```

```objectivec
ZMVideoSDKVideoHelper *videoHelper = [[ZMVideoSDK sharedVideoSDK] getVideoHelper];
if ([videoHelper canEnableAlphaChannelMode]) {
    [videoHelper isDeviceSupportAlphaChannelMode]; // Determines whether the device hardware capabilities are capable of supporting video alpha mode.
    [videoHelper enableAlphaChannelMode:TRUE]; // TRUE/FALSE to enable/disable alpha channel.
    [videoHelper isAlphaChannelModeEnabled];
}
```

## Alpha channel callbacks

The `onVideoAlphaChannelStatusChanged` callback is triggered when alpha channel mode is turned on or off. After turning on the alpha channel, the raw video data will have two more values, `alphaBuffer` for the alpha data buffer and `alphaBufferLen` for the alpha data buffer length, included in the same `onRawDataFrameReceived` callback.

Now that you've received the data, edit the raw data to suit your use case.

```swift
func onVideoAlphaChannelStatusChanged(_ isAlphaModeOn: Bool) {

}

func onRawDataFrameReceived(_ data: ZMVideoSDKYUVRawDataI420) {
    data.alphaBuffer // Only if alpha data exists, then will contain buffer address. Otherwise null.
    data.alphaBufferLen
}
```

```objectivec
- (void)onVideoAlphaChannelStatusChanged:(BOOL)isAlphaModeOn {

}

- (void)onRawDataFrameReceived:(ZMVideoSDKYUVRawDataI420*)data {
    data.alphaBuffer; // Only if alpha data exists, then will contain buffer address. Otherwise null.
    data.alphaBufferLen;
}
```