# AudioQueueEnqueueBuffer(_:_:_:_:) Adds a buffer to the buffer queue of a recording or playback audio queue. ``` func AudioQueueEnqueueBuffer(_ inAQ: AudioQueueRef, _ inBuffer: AudioQueueBufferRef, _ inNumPacketDescs: UInt32, _ inPacketDescs: UnsafePointer?) -> OSStatus ``` ## Parameters `inAQ` The audio queue that owns the audio queue buffer. `inBuffer` The audio queue buffer to add to the buffer queue. `inNumPacketDescs` The number of packets of audio data in the `inBuffer` parameter. Use a value of `0` for any of the following situations: - When playing a constant bit rate (CBR) format. - When the audio queue is a recording (input) audio queue. - When the buffer you are reenqueuing was allocated with the [`AudioQueueAllocateBufferWithPacketDescriptions(_:_:_:_:)`](/documentation/AudioToolbox/AudioQueueAllocateBufferWithPacketDescriptions(_:_:_:_:)) function. In this case, your callback should describe the buffer’s packets in the buffer’s `mPacketDescriptions` and `mPacketDescriptionCount` fields. `inPacketDescs` An array of packet descriptions. Use a value of `NULL` for any of the following situations: - When playing a constant bit rate (CBR) format. - When the audio queue is an input (recording) audio queue. - When the buffer you are reenqueuing was allocated with the [`AudioQueueAllocateBufferWithPacketDescriptions(_:_:_:_:)`](/documentation/AudioToolbox/AudioQueueAllocateBufferWithPacketDescriptions(_:_:_:_:)) function. In this case, your callback should describe the buffer’s packets in the buffer’s `mPacketDescriptions` and `mPacketDescriptionCount` fields. ## Return Value A result code. See Result Codes. ## Discussion Audio queue callbacks use this function to reenqueue buffers—placing them “last in line” in a buffer queue. A playback (or *output*) callback reenqueues a buffer after the buffer is filled with fresh audio data (typically from a file). A recording (or *input*) callback reenqueues a buffer after the buffer’s contents were written (typically to a file). --- 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)