# AudioFileGetUserDataAtOffset(_:_:_:_:_:_:) Gets part of the data from a chunk in an audio file. ``` func AudioFileGetUserDataAtOffset(_ inAudioFile: AudioFileID, _ inUserDataID: UInt32, _ inIndex: UInt32, _ inOffset: Int64, _ ioUserDataSize: UnsafeMutablePointer, _ outUserData: UnsafeMutableRawPointer) -> OSStatus ``` ## Parameters `inAudioFile` The audio file whose chunk you want to get data from. `inUserDataID` The four-character code of the designated chunk. `inIndex` An index that specifies which chunk with the four-character code specified in the `inUserDataID` parameter you want to query. `inOffset` An offset from the first byte of the chunk to the first byte to get. `ioUserDataSize` On input, a pointer to the size of the buffer that contains the designated chunk. On output, a pointer to the size of bytes that the system copied to the buffer. `outUserData` A pointer to a buffer in which to copy the chunk data. ## Return Value A result code if there’s an error (see Result Codes) or `noErr` if the operation succeeds. ## Discussion See [`AudioFileGetUserDataSize64(_:_:_:_:)`](/documentation/AudioToolbox/AudioFileGetUserDataSize64(_:_:_:_:)) for an example of using this function to parse the Audio Definition Model (ADM) of a BW64 file, which is 64-bit and based on WAVE. --- 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)