# Raw video processing (/en/realtime-media/video/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. Video SDK provides the capability to pre-process and post-process the captured video data, allowing you to implement custom playback effects.

      
  
      
    ## Understand the tech [#understand-the-tech-1]

    Video 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 [#prerequisites-1]

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

    ## Implement raw video processing [#implement-raw-video-processing-1]

    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 [#reference-1]

    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 [#sample-project-1]

    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 [#api-reference-1]

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