# Raw video processing (/en/realtime-media/rtc/build/capture-and-render-video/raw-video-processing/ios)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

In certain use-cases, it is necessary to process raw video captured through the camera to achieve desired functionality or enhance the user experience. RTC SDK provides the capability to pre-process and post-process the captured video data, allowing you to implement custom playback effects.

      
  
      
## Understand the tech

RTC SDK enables you to pre-process the captured video frames before sending the data to the encoder or perform post-processing on the received video frames after sending the data to the decoder.

The following figure shows the video data processing flow in the SDK video module.

**Process raw video**

![image](https://assets-docs.agora.io/images/video-sdk/video-module-data-processing.svg)

* Position (2) corresponds to the `onCaptureVideoFrame` callback.
* Position (3) corresponds to the `onPreEncodeVideoFrame` callback.
* Position (4) corresponds to the`onRenderVideoFrame` callback.

## Prerequisites

Ensure that you have implemented the [SDK quickstart](/en/realtime-media/rtc/get-started-sdk) in your project.

## Implement raw video processing

To implement raw video data functionality in your project, refer to the following steps:

1. Before joining the channel, call `setVideoFrameDelegate` to register the video observer object.

2. Implement the `onCaptureVideoFrame` and `onRenderVideoFrame` callbacks to handle the capture and rendering of video frames.

   <CalloutContainer type="warning">
     <CalloutDescription>
       When modifying parameters in a `videoFrame`, ensure that the updated parameters match the actual video frame in the buffer. Failure to do so may result in unexpected rotation or distortion in both the local preview and the remote video.
     </CalloutDescription>
   </CalloutContainer>

```swift
class RawVideoDataMain: BaseViewController {
  var localVideo = Bundle.loadVideoView(type: .local, audioOnly: false)
  var remoteVideo = Bundle.loadVideoView(type: .remote, audioOnly: false)

  @IBOutlet weak var container: AGEVideoContainer!
  // Define agoraKit variable
  var agoraKit: AgoraRtcEngineKit!

  // ...
  // Initialize agoraKit and register the corresponding callbacks
  agoraKit = AgoraRtcEngineKit.sharedEngine(with: config, delegate: self)

  // Call setVideoFrameDelegate to register the video observer object
  agoraKit.setVideoFrameDelegate (self)

  // ...

  // Implement the AgoraVideoFrameDelegate protocol extension in the current class
  extension RawVideoDataMain: AgoraVideoFrameDelegate {

    // Implement the onCaptureVideoFrame callback
    func onCaptureVideoFrame(_ videoFrame: AgoraOutputVideoFrame) -> Bool {
      return true
    }

    // Implement the onScreenCaptureVideoFrame callback
    func onScreenCaptureVideoFrame(_ videoFrame: AgoraOutputVideoFrame) -> Bool {
      return true
    }

    // Implement the onRenderVideoFrame callback
    func onRenderVideoFrame(_ videoFrame: AgoraOutputVideoFrame, uid: UInt, channelId: String) -> Bool {
      return true
    }
  }
}
```

## Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

### Sample project

Agora provides an open source sample project [RawVideoData](https://github.com/AgoraIO/API-Examples/tree/main/iOS/APIExample/APIExample/Examples/Advanced/RawVideoData) on GitHub. Download it or view the source code for a more detailed example.

### API reference

* [`setVideoFrameDelegate(_:)`](https://api-ref.agora.io/en/video-sdk/ios/4.x/documentation/agorartckit/agorartcenginekit/setvideoframedelegate%28_:%29)
* [`onRenderVideoFrame(_:uid:channelId:)`](https://api-ref.agora.io/en/video-sdk/ios/4.x/documentation/agorartckit/agoravideoframedelegate/onrendervideoframe%28_\:uid\:channelid:%29)
* [`onCapture(_:sourceType:)`](https://api-ref.agora.io/en/video-sdk/ios/4.x/documentation/agorartckit/agoravideoframedelegate/oncapture%28_\:sourcetype:%29)