# AVAssetReaderOutput.Provider An object that reads a collection of samples of a common media type from an asset reader. ``` class Provider where Payload : AVAssetReaderOutput.SupportedPayload ``` ## Topics ### Reading media data [`func captionsNotPresentInPreviousGroups(in: AVCaptionGroup) -> [AVCaption]`](/documentation/AVFoundation/AVAssetReaderOutput/Provider/captionsNotPresentInPreviousGroups(in:)) Returns the set of captions that are present in the given group but were not present in any group previously vended by calls to next(). [`func next() async throws -> Payload?`](/documentation/AVFoundation/AVAssetReaderOutput/Provider/next()) Returns the next piece of media data. --- 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)