# AudioConverterFillComplexBuffer(_:_:_:_:_:_:) Converts audio data supplied by a callback function, supporting non-interleaved and packetized formats. ``` func AudioConverterFillComplexBuffer(_ inAudioConverter: AudioConverterRef, _ inInputDataProc: AudioConverterComplexInputDataProc, _ inInputDataProcUserData: UnsafeMutableRawPointer?, _ ioOutputDataPacketSize: UnsafeMutablePointer, _ outOutputData: UnsafeMutablePointer, _ outPacketDescription: UnsafeMutablePointer?) -> OSStatus ``` ## Parameters `inAudioConverter` The audio converter to use for format conversion. `inInputDataProc` A callback function that supplies audio data to convert. This callback is invoked repeatedly as the converter is ready for new input data. `inInputDataProcUserData` Custom data for use by your application when receiving a callback invocation. `ioOutputDataPacketSize` On input, the size of the output buffer (in the `outOutputData` parameter), expressed in number packets in the audio converter’s output format. On output, the number of packets of converted data that were written to the output buffer. `outOutputData` On output, the converted audio data. `outPacketDescription` On input, must point to a block of memory capable of holding the number of packet descriptions specified in the `ioOutputDataPacketSize` parameter. (See *Audio Format Services Reference* for functions that let you determine whether an audio format uses packet descriptions). If not `NULL` on output and if the audio converter’s output format uses packet descriptions, then this parameter contains an array of packet descriptions. ## Return Value A result code. ## Discussion Use this function for all audio data format conversions except for the special case of converting from one linear PCM format to another with no sample rate conversion. --- 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)