# AudioFileStreamSeek(_:_:_:_:) Provides a byte offset for a specified packet in the data stream. ``` func AudioFileStreamSeek(_ inAudioFileStream: AudioFileStreamID, _ inPacketOffset: Int64, _ outDataByteOffset: UnsafeMutablePointer, _ ioFlags: UnsafeMutablePointer) -> OSStatus ``` ## Parameters `inAudioFileStream` The ID of the parser to which you wish to provide a byte offset. The parser ID is returned by the [`AudioFileStreamOpen(_:_:_:_:_:)`](/documentation/AudioToolbox/AudioFileStreamOpen(_:_:_:_:_:)) function. `inPacketOffset` The number of packets from the beginning of the file of the packet whose byte offset you wish to have returned. `outDataByteOffset` On output, the absolute byte offset of the packet whose offset you specify in the `inPacketOffset` parameter. For audio file formats that do not contain packet tables, the returned offset may be an estimate. `ioFlags` On output, if the `outDataByteOffset` parameter returns an estimate, this parameter returns the constant `kAudioFileStreamSeekFlag_OffsetIsEstimated`. Currently, no input flags are defined for this call. ## Return Value A result code. See Result Codes. ## Discussion After you call this function, the parser assumes the next data passed to the [`AudioFileStreamParseBytes(_:_:_:_:)`](/documentation/AudioToolbox/AudioFileStreamParseBytes(_:_:_:_:)) function starts from the byte offset returned in the `outDataByteOffset` parameter. ## See Also [`AudioFileStreamParseBytes(_:_:_:_:)`](/documentation/AudioToolbox/AudioFileStreamParseBytes(_:_:_:_:)) Passes audio file stream data to the parser. [`AudioFileStreamOpen(_:_:_:_:_:)`](/documentation/AudioToolbox/AudioFileStreamOpen(_:_:_:_:_:)) Creates and opens a new audio file stream parser. --- 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)