# Audio Format Identifiers Identifiers for supported audio formats. ## Discussion Use these identifiers to test for the presence of audio codecs on a system. If a given codec is present, you can use its identifier to specify that codec for data encoding or decoding, according to the capabilities of the codec. For more information, see . ## Topics ### Format identifiers [`var kAudioFormat60958AC3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormat60958AC3) A key that specifies the AC-3 codec, which provides data packaged for transport over an IEC 60958-compliant digital audio interface, and uses standard flags. [`var kAudioFormatAC3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAC3) A key that specifies the AC-3 codec, and uses no flags. [`var kAudioFormatAES3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAES3) A key that specifies the codec defined by the AES3-2003 standard, and uses no flags. [`var kAudioFormatALaw: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatALaw) A key that specifies the A-law 2:1 codec, and uses no flags. [`var kAudioFormatAMR: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAMR) A key that specifies the Adaptive Multi-Rate (AMR) narrow band speech codec, and uses no flags. [`var kAudioFormatAMR_WB: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAMR_WB) A key that specifies the AMR Wideband speech codec, and uses no flags. [`var kAudioFormatAppleIMA4: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAppleIMA4) A key that specifies Apple’s implementation of the IMA 4:1 ADPCM codec, and uses no flags. [`var kAudioFormatAppleLossless: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAppleLossless) A key that specifies the Apple Lossless codec, and uses flags to indicate the bit depth of the source material. [`var kAudioFormatAudible: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatAudible) A key that specifies the codec for Audible audio books, and uses no flags. [`var kAudioFormatDVIIntelIMA: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatDVIIntelIMA) A key that specifies the codec defined by DVI/Intel IMA ADPCM - ACM code 17, and uses no flags. [`var kAudioFormatEnhancedAC3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatEnhancedAC3) A key that specifies the Enhanced AC-3 codec, and uses no flags. [`var kAudioFormatFLAC: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatFLAC) A key that specifies the Free Lossless Audio Codec (FLAC), and uses flags to indicate the bit depth of the source material. [`var kAudioFormatLinearPCM: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatLinearPCM) A key that specifies the linear PCM codec, and uses the standard flags. [`var kAudioFormatMACE3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMACE3) A key that specifies the MACE 3:1 codec, and uses no flags. [`var kAudioFormatMACE6: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMACE6) A key that specifies the MACE C:1 codec, and uses no flags. [`var kAudioFormatMIDIStream: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMIDIStream) A key that specifies the MIDI stream codec, and uses no flags. [`var kAudioFormatMPEG4AAC: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC) A key that specifies the MPEG-4 AAC Low Complexity codec, and uses no flags. [`var kAudioFormatMPEG4AAC_ELD: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_ELD) A key that specifies the MPEG-4 Enhanced Low Delay AAC codec, and uses no flags. [`var kAudioFormatMPEG4AAC_ELD_SBR: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_ELD_SBR) A key that specifies the MPEG-4 Enhanced Low Delay AAC codec with a spectral band replication (SBR) extension layer, and uses no flags. [`var kAudioFormatMPEG4AAC_ELD_V2: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_ELD_V2) A key that specifies the MPEG-4 Enhanced Low Delay AAC version 2 codec, and uses no flags. [`var kAudioFormatMPEG4AAC_HE: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_HE) A key that specifies the MPEG-4 High-Efficiency AAC codec, and uses no flags. [`var kAudioFormatMPEG4AAC_HE_V2: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_HE_V2) A key that specifies the MPEG-4 High-Efficiency AAC version 2 codec, and uses no flags. [`var kAudioFormatMPEG4AAC_LD: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_LD) A key that specifies the MPEG-4 Low Delay AAC codec, and uses no flags. [`var kAudioFormatMPEG4AAC_Spatial: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4AAC_Spatial) A key that specifies the MPEG-4 Spatial Audio Coding codec, and uses no flags. [`var kAudioFormatMPEG4CELP: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4CELP) A key that specifies the MPEG-4 CELP codec, and uses flags to indicate the specific kind of data. [`var kAudioFormatMPEG4HVXC: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4HVXC) A key that specifies the MPEG-4 HVXC codec, and uses no flags. [`var kAudioFormatMPEG4TwinVQ: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEG4TwinVQ) A key that specifies the MPEG-4 TwinVQ codec, and uses no flags. [`var kAudioFormatMPEGD_USAC: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEGD_USAC) A key that specifies the MPEG-D Unified Speech and Audio Coding codec, and uses no flags. [`var kAudioFormatMPEGLayer1: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEGLayer1) A key that specifies the MPEG-1/2, Layer I audio codec, and uses no flags. [`var kAudioFormatMPEGLayer2: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEGLayer2) A key that specifies the MPEG-1/2, Layer II audio codec, and uses no flags. [`var kAudioFormatMPEGLayer3: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMPEGLayer3) A key that specifies the MPEG-1/2, Layer III audio codec, and uses no flags. [`var kAudioFormatMicrosoftGSM: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatMicrosoftGSM) A key that specifies the Microsoft GSM 6.10 - ACM code 49 codec, and uses no flags. [`var kAudioFormatOpus: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatOpus) A key that specifies the Opus codec, and uses no flags. [`var kAudioFormatParameterValueStream: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatParameterValueStream) A key that specifies the A side-chain of float 32 data that an audio unit provides for sending high-density parameter value control information, and uses no flags. [`var kAudioFormatQDesign: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatQDesign) A key that specifies the QDesign music codec, and uses no flags. [`var kAudioFormatQDesign2: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatQDesign2) A key that specifies the QDesign 2 music codec, and uses no flags. [`var kAudioFormatQUALCOMM: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatQUALCOMM) A key that specifies the Qualcomm PureVoice codec, and uses no flags. [`var kAudioFormatTimeCode: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatTimeCode) A key that specifies the A stream of audio timestamp structures, and uses audio timestamp flags. [`var kAudioFormatULaw: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatULaw) A key that specifies the μ-Law 2:1 codec, and uses no flags. [`var kAudioFormatiLBC: AudioFormatID`](/documentation/CoreAudioTypes/kAudioFormatiLBC) A key that specifies the internet Low Bitrate Codec (iLBC) narrow band speech codec, and uses no flags. --- 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)