# CMSampleBufferGetAudioStreamPacketDescriptions(_:allocatedSize:packetDescriptionsOut:packetDescriptionsSizeNeededOut:) Creates an array of audio stream packet descriptions. ``` func CMSampleBufferGetAudioStreamPacketDescriptions(_ sbuf: CMSampleBuffer, allocatedSize packetDescriptionsSize: Int, packetDescriptionsOut: UnsafeMutablePointer?, packetDescriptionsSizeNeededOut: UnsafeMutablePointer?) -> OSStatus ``` ## Parameters `sbuf` `CMSampleBuffer` being accessed. `packetDescriptionsSize` Size of `packetDescriptionsOut` as allocated by the caller. `packetDescriptionsOut` Allocated by the caller, receives the packet descriptions for the samples in the `CMSampleBuffer`. If non-`NULL` and `packetDescriptionsSize` is too small, `kFigSampleBufferError_ArrayTooSmall` is returned. `packetDescriptionsSizeNeededOut` Used to query for the correct size required for `packetDescriptionsOut`. May be `NULL`. ## Return Value A result code. See [Sample Buffer Error Codes](/documentation/CoreMedia/sample-buffer-errors). ## Discussion Creates an array of `AudioStreamPacketDescriptions` for the variable bytes per packet or variable frames per packet audio data in the provided `CMSampleBuffer`. Constant bit rate, constant frames-per-packet audio yields a return value of `noErr` and no packet descriptions. This API is specific to audio format sample buffers, and will return `kCMSampleBufferError_InvalidMediaTypeForOperation` if called with a non-audio sample buffer. --- 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)