# refineSampleLocation(_:refinementData:refinementDataLength:refinedLocation:) Produces an exact sample location based on the estimated sample location and refinement data that you specify. ``` optional func refineSampleLocation(_ estimatedSampleLocation: AVSampleCursorStorageRange, refinementData: UnsafePointer, refinementDataLength: Int, refinedLocation refinedLocationOut: UnsafeMutablePointer) throws ``` ## Parameters `estimatedSampleLocation` The estimated sample location. `refinementData` The refinement data. `refinementDataLength` The length of the refinement data in bytes. `refinedLocationOut` The starting file offset and size of the sample in bytes. ## Discussion Use [`estimatedSampleLocation()`](/documentation/MediaExtension/MESampleCursor/estimatedSampleLocation()) to obtain the estimated sample location to pass to this method. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)