# Instance Codec Properties Properties that can be set or read on an instance of the audio codec. ## Discussion These properties are used with the [`AudioCodecGetProperty(_:_:_:_:)`](/documentation/AudioToolbox/AudioCodecGetProperty(_:_:_:_:)) and [`AudioCodecSetProperty(_:_:_:_:)`](/documentation/AudioToolbox/AudioCodecSetProperty(_:_:_:_:)) functions. These properties are dependent on the codec’s current state. A property may be read/write or read only, depending on the data format of the codec. These properties may have different values depending on whether the codec is in the initialized state. You can set writable properties only when the codec is not initialized. All properties can be read at any time the codec is open. ## Topics ### Constants [`var kAudioCodecPropertyAdjustLocalQuality: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyAdjustLocalQuality) [`var kAudioCodecPropertyApplicableBitRateRange: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyApplicableBitRateRange) [`var kAudioCodecPropertyApplicableInputSampleRates: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyApplicableInputSampleRates) [`var kAudioCodecPropertyApplicableOutputSampleRates: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyApplicableOutputSampleRates) [`var kAudioCodecPropertyBitRateControlMode: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyBitRateControlMode) [`var kAudioCodecPropertyCurrentInputChannelLayout: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentInputChannelLayout) [`var kAudioCodecPropertyCurrentInputFormat: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentInputFormat) [`var kAudioCodecPropertyCurrentInputSampleRate: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentInputSampleRate) [`var kAudioCodecPropertyCurrentOutputChannelLayout: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentOutputChannelLayout) [`var kAudioCodecPropertyCurrentOutputFormat: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentOutputFormat) [`var kAudioCodecPropertyCurrentOutputSampleRate: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentOutputSampleRate) [`var kAudioCodecPropertyCurrentTargetBitRate: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyCurrentTargetBitRate) [`var kAudioCodecPropertyDelayMode: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyDelayMode) [`var kAudioCodecPropertyDynamicRangeControlMode: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyDynamicRangeControlMode) [`var kAudioCodecPropertyFormatList: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyFormatList) [`var kAudioCodecPropertyHasVariablePacketByteSizes: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyHasVariablePacketByteSizes) [`var kAudioCodecPropertyInputBufferSize: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyInputBufferSize) [`var kAudioCodecPropertyIsInitialized: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyIsInitialized) [`var kAudioCodecPropertyMagicCookie: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyMagicCookie) [`var kAudioCodecPropertyMaximumPacketByteSize: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyMaximumPacketByteSize) [`var kAudioCodecPropertyPacketFrameSize: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyPacketFrameSize) [`var kAudioCodecPropertyPacketSizeLimitForVBR: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyPacketSizeLimitForVBR) [`var kAudioCodecPropertyPaddedZeros: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyPaddedZeros) [`var kAudioCodecPropertyPrimeInfo: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyPrimeInfo) [`var kAudioCodecPropertyPrimeMethod: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyPrimeMethod) [`var kAudioCodecPropertyProgramTargetLevel: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyProgramTargetLevel) [`var kAudioCodecPropertyProgramTargetLevelConstant: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyProgramTargetLevelConstant) [`var kAudioCodecPropertyQualitySetting: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyQualitySetting) [`var kAudioCodecPropertyRecommendedBitRateRange: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyRecommendedBitRateRange) [`var kAudioCodecPropertySettings: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertySettings) [`var kAudioCodecPropertySoundQualityForVBR: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertySoundQualityForVBR) [`var kAudioCodecPropertyUsedInputBufferSize: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyUsedInputBufferSize) [`var kAudioCodecPropertyAdjustCompressionProfile: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyAdjustCompressionProfile) [`var kAudioCodecPropertyAdjustTargetLevel: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyAdjustTargetLevel) [`var kAudioCodecPropertyAdjustTargetLevelConstant: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyAdjustTargetLevelConstant) [`var kAudioCodecPropertyBitRateForVBR: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyBitRateForVBR) [`var kAudioCodecPropertyEmploysDependentPackets: AudioCodecPropertyID`](/documentation/AudioToolbox/kAudioCodecPropertyEmploysDependentPackets) --- Copyright © 2026 Apple Inc. 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