# Audio Queue Hardware Codec Policy ## Topics ### Constants [`var kAudioQueueHardwareCodecPolicy_Default: UInt32`](/documentation/AudioToolbox/kAudioQueueHardwareCodecPolicy_Default) If the required codec is available in both hardware and software implementations, the audio queue will use a hardware codec if its audio session category permits; it will use a software codec otherwise. If the required codec is available in only one form, that codec implementation is used. [`var kAudioQueueHardwareCodecPolicy_PreferHardware: UInt32`](/documentation/AudioToolbox/kAudioQueueHardwareCodecPolicy_PreferHardware) The audio queue will use a hardware codec if one is available and if its use permitted by the audio session category that you have set; otherwise, it will use a software codec if one is available. [`var kAudioQueueHardwareCodecPolicy_PreferSoftware: UInt32`](/documentation/AudioToolbox/kAudioQueueHardwareCodecPolicy_PreferSoftware) The audio queue will use a software codec if one is available; if not, it will use a hardware codec if one is available and if its use is permitted by the audio session category that you have set. [`var kAudioQueueHardwareCodecPolicy_UseHardwareOnly: UInt32`](/documentation/AudioToolbox/kAudioQueueHardwareCodecPolicy_UseHardwareOnly) The audio queue will use a hardware codec if one is available and if its use is permitted by the audio session category that you have set. [`var kAudioQueueHardwareCodecPolicy_UseSoftwareOnly: UInt32`](/documentation/AudioToolbox/kAudioQueueHardwareCodecPolicy_UseSoftwareOnly) The audio queue will use a software codec if one is available. --- 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)