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AudioUnit Framework Reference Audio Unit Parameters Reference

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Audio Unit Parameters Reference

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Import Statement


Swift

import AudioUnit

Objective-C

@import AudioUnit;

An audio unit parameter is a key, defined by the audio unit it applies to, whose corresponding value specifies the setting for an adjustable attribute such as volume, pitch, or filter cutoff frequency. Parameters are typically varied by the user during audio processing, by way of a user interface that you provide. All parameter values are of the same data type: 32-bit floating point. The audio unit that defines a parameter also defines the meaning of the value, the default value, and the permissible range.

Constants

  • Parameters for the 3D Mixer unit.

    Declaration

    Swift

    var k3DMixerParam_Azimuth: Int { get } var k3DMixerParam_Elevation: Int { get } var k3DMixerParam_Distance: Int { get } var k3DMixerParam_Gain: Int { get } var k3DMixerParam_PlaybackRate: Int { get } var k3DMixerParam_Enable: Int { get } var k3DMixerParam_MinGain: Int { get } var k3DMixerParam_MaxGain: Int { get } var k3DMixerParam_ReverbBlend: Int { get } var k3DMixerParam_GlobalReverbGain: Int { get } var k3DMixerParam_OcclusionAttenuation: Int { get } var k3DMixerParam_ObstructionAttenuation: Int { get }

    Objective-C

    enum { k3DMixerParam_Azimuth = 0, k3DMixerParam_Elevation = 1, k3DMixerParam_Distance = 2, k3DMixerParam_Gain = 3, k3DMixerParam_PlaybackRate = 4, k3DMixerParam_Enable = 5, k3DMixerParam_MinGain = 6, k3DMixerParam_MaxGain = 7, k3DMixerParam_ReverbBlend = 8, k3DMixerParam_GlobalReverbGain = 9, k3DMixerParam_OcclusionAttenuation = 10, k3DMixerParam_ObstructionAttenuation = 11 };

    Constants

    • k3DMixerParam_Azimuth

      k3DMixerParam_Azimuth

      Specifies the horizontal azimuth of the sound source relative to the listener.

      Used on the input scope. Range is from –180° through +180°, each of which indicate a source position that is directly behind the listener. –90° indicates extreme left; +90° indicates extreme right. Default is , which indicates straight ahead.

      For the azimuth setting to be audible, the 3D Mixer unit’s k3DMixerParam_Distance parameter value must be set to a positive value.

      Available in iOS 2.0 and later

    • k3DMixerParam_Elevation

      k3DMixerParam_Elevation

      Specifies the vertical elevation of the sound source relative to the listener.

      Used on the input scope. Range is from –90° (straight down) through +90° (straight up). Default is , indicating a line parallel to the earth’s surface.

      For the elevation setting to be audible, the 3D Mixer unit’s k3DMixerParam_Distance parameter value must be set to a positive value.

      Available in iOS 2.0 and later

    • k3DMixerParam_Distance

      k3DMixerParam_Distance

      Specifies the apparent distance of the sound source from the listener.

      Used on the input scope. Range is from 0 through 10,000 meters. Default is 0 meters, which indicates that the sound source and the listener are positioned together at the same point.

      For changes to the k3DMixerParam_Azimuth or k3DMixerParam_Elevation parameters to be audible, set this parameter to a positive value.

      Available in iOS 2.0 and later

    • k3DMixerParam_Gain

      k3DMixerParam_Gain

      Specifies audio gain.

      Used on the input and output scopes. Range is from –120 dB (near silence) through 20 dB. Default is 0 dB, indicating unity gain.

      Available in iOS 2.0 and later

    • k3DMixerParam_PlaybackRate

      k3DMixerParam_PlaybackRate

      Specifies the playback rate relative to normal-speed playback.

      Used on the input scope. Range is from 0.5 (half speed) through 2.0 (twice normal speed). Default value is 1.0, corresponding to normal-speed playback.

      When you vary the playback rate away from 1.0, playback pitch changes accordingly. For example, using a playback rate of 2.0, sounds are higher in pitch by one octave.

      Available in iOS 2.0 and later

    • k3DMixerParam_Enable

      k3DMixerParam_Enable

      Enables or disables a mixer input.

      Use 0 to disable, or mute, an input. Use 1 to enable, or unmute, an input. Inputs are enabled by default.

      Available in iOS 4.0 and later

    • k3DMixerParam_MinGain

      k3DMixerParam_MinGain

      Specifies a lower constraint for range of the k3DMixerParam_Gain parameter.

      Range is from 0.0 through 1.0. Default value is 0.0.

      Available in iOS 4.0 and later

    • k3DMixerParam_MaxGain

      k3DMixerParam_MaxGain

      Specifies an upper constraint for range of the k3DMixerParam_Gain parameter.

      Range is from 0.0 through 1.0. Default value is 1.0.

      Available in iOS 4.0 and later

    • k3DMixerParam_ReverbBlend

      k3DMixerParam_ReverbBlend

      Specifies the dry/wet blend for a mixer input, using an equal-power percentage.

      Range is from 0.0 through 100.0. Used on the input scope.

      Available in iOS 5.0 and later

    • k3DMixerParam_GlobalReverbGain

      k3DMixerParam_GlobalReverbGain

      Specifies the reverb gain, globally, for the mixer unit, in decibels.

      Range is from –40.0 through +40.0. Used on the global scope.

      Available in iOS 5.0 and later

    • k3DMixerParam_OcclusionAttenuation

      k3DMixerParam_OcclusionAttenuation

      Specifies the amount of 5 kHz low-pass filter attenuation for an input, in decibels, applied before the send to the mixer’s reverb effect.

      Range is from –100.0 through 0.0. A value of 0 results in no attenuation. A value of –100 results in maximum muffling effect. See also k3DMixerParam_ObstructionAttenuation.

      Use this parameter to simulate the listener and the sound source being in different rooms, or one being outside and the other inside. The simulation is that not only is line of sight blocked, but all acoustic reflections are blocked as well.

      Available in iOS 5.0 and later

    • k3DMixerParam_ObstructionAttenuation

      k3DMixerParam_ObstructionAttenuation

      Specifies the amount of 5 kHz low-pass filter attenuation for an input, in decibels, applied after the send to the mixer’s reverb effect.

      Range is from –100.0 through 0.0. A value of 0 results in no attenuation. A value of –100 results in maximum muffling effect. See also k3DMixerParam_OcclusionAttenuation.

      Use this parameter to simulate an object that blocks the line of sight between the listener and the sound source, but does not block all acoustic reflections.

      Available in iOS 5.0 and later

  • Parameters for the Multichannel Mixer unit.

    Declaration

    Swift

    var kMultiChannelMixerParam_Volume: Int { get } var kMultiChannelMixerParam_Enable: Int { get } var kMultiChannelMixerParam_Pan: Int { get } var kMultiChannelMixerParam_PreAveragePower: Int { get } var kMultiChannelMixerParam_PrePeakHoldLevel: Int { get } var kMultiChannelMixerParam_PostAveragePower: Int { get } var kMultiChannelMixerParam_PostPeakHoldLevel: Int { get }

    Objective-C

    enum { kMultiChannelMixerParam_Volume = 0, kMultiChannelMixerParam_Enable = 1, kMultiChannelMixerParam_Pan = 2, kMultiChannelMixerParam_PreAveragePower = 1000, kMultiChannelMixerParam_PrePeakHoldLevel = 2000, kMultiChannelMixerParam_PostAveragePower = 3000, kMultiChannelMixerParam_PostPeakHoldLevel = 4000 };

    Constants

    • kMultiChannelMixerParam_Volume

      kMultiChannelMixerParam_Volume

      Sets the audio gain for a mixer input or the output.

      Range is from 0 (for silence) through 1 (for unity gain).

      Available in iOS 2.0 and later

    • kMultiChannelMixerParam_Enable

      kMultiChannelMixerParam_Enable

      Enables or disables a mixer input.

      Use 0 to disable, or mute, an input. Use 1 to enable, or unmute, an input.

      Available in iOS 2.0 and later

    • kMultiChannelMixerParam_Pan

      kMultiChannelMixerParam_Pan

      Sets the stereo panning position for a mixer input.

      Range is from -1 (extreme left) through +1 (extreme right). Default value is 0, indicating center.

      Available in iOS 4.0 and later

    • kMultiChannelMixerParam_PreAveragePower

      kMultiChannelMixerParam_PreAveragePower

      Indicates the average “pre” power in decibels (dB). Read only.

      Available in iOS 2.0 and later

    • kMultiChannelMixerParam_PrePeakHoldLevel

      kMultiChannelMixerParam_PrePeakHoldLevel

      Indicates the “pre” peak hold level in decibels (dB). Read only.

      Available in iOS 2.0 and later

    • kMultiChannelMixerParam_PostAveragePower

      kMultiChannelMixerParam_PostAveragePower

      Indicates the average “post” power in decibels (dB). Read only.

      Available in iOS 2.0 and later

    • kMultiChannelMixerParam_PostPeakHoldLevel

      kMultiChannelMixerParam_PostPeakHoldLevel

      Indicates the “post” peak hold level in decibels (dB). Read only.

      Available in iOS 2.0 and later

  • Parameters for the Bandpass unit.

    Declaration

    Swift

    var kBandpassParam_CenterFrequency: Int { get } var kBandpassParam_Bandwidth: Int { get }

    Objective-C

    enum { kBandpassParam_CenterFrequency = 0, kBandpassParam_Bandwidth = 1 };

    Constants

    • kBandpassParam_CenterFrequency

      kBandpassParam_CenterFrequency

      Range is from 20 Hz to less than the Nyquist frequency (half the sample rate). Default value is 5,000 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kBandpassParam_Bandwidth

      kBandpassParam_Bandwidth

      Range is from 100 through 12000 cents. Default value is 600 cents. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Highpass unit.

    Declaration

    Swift

    var kHipassParam_CutoffFrequency: Int { get } var kHipassParam_Resonance: Int { get }

    Objective-C

    enum { kHipassParam_CutoffFrequency = 0, kHipassParam_Resonance = 1 };

    Constants

    • kHipassParam_CutoffFrequency

      kHipassParam_CutoffFrequency

      Range is from 10 Hz to less than the Nyquist frequency (half the sample rate). Default value is 6900 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kHipassParam_Resonance

      kHipassParam_Resonance

      Range is from –20 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Lowpass unit.

    Declaration

    Swift

    var kLowPassParam_CutoffFrequency: Int { get } var kLowPassParam_Resonance: Int { get }

    Objective-C

    enum { kLowPassParam_CutoffFrequency = 0, kLowPassParam_Resonance = 1 };

    Constants

    • kLowPassParam_CutoffFrequency

      kLowPassParam_CutoffFrequency

      Range is from 10 Hz to less than the Nyquist frequency (half the sample rate). Default value is 6900 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kLowPassParam_Resonance

      kLowPassParam_Resonance

      Range is from –20 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the High Shelf Filter unit.

    Declaration

    Swift

    var kHighShelfParam_CutOffFrequency: Int { get } var kHighShelfParam_Gain: Int { get }

    Objective-C

    enum { kHighShelfParam_CutOffFrequency = 0, kHighShelfParam_Gain = 1 };

    Constants

    • kHighShelfParam_CutOffFrequency

      kHighShelfParam_CutOffFrequency

      Range is from 10000 Hz to less than the Nyquist frequency (half the sample rate). Default value is 10000 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kHighShelfParam_Gain

      kHighShelfParam_Gain

      Range is from –40 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Low Shelf Filter unit.

    Declaration

    Swift

    var kAULowShelfParam_CutoffFrequency: Int { get } var kAULowShelfParam_Gain: Int { get }

    Objective-C

    enum { kAULowShelfParam_CutoffFrequency = 0, kAULowShelfParam_Gain = 1 };

    Constants

    • kAULowShelfParam_CutoffFrequency

      kAULowShelfParam_CutoffFrequency

      Range is from 10 through 200 Hz. Default value is 80 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kAULowShelfParam_Gain

      kAULowShelfParam_Gain

      Range is from –40 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Parametric EQ unit.

    Declaration

    Swift

    var kParametricEQParam_CenterFreq: Int { get } var kParametricEQParam_Q: Int { get } var kParametricEQParam_Gain: Int { get }

    Objective-C

    enum { kParametricEQParam_CenterFreq = 0, kParametricEQParam_Q = 1, kParametricEQParam_Gain = 2 };

    Constants

    • kParametricEQParam_CenterFreq

      kParametricEQParam_CenterFreq

      Range is from 20 Hz to less than the Nyquist frequency (half the sample rate). Default value is 2000 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kParametricEQParam_Q

      kParametricEQParam_Q

      Range is from 0.1 through 20 (Q is an absolute value and has no unit). Default value is 1.0. Used on the Global scope.

      Available in iOS 5.0 and later

    • kParametricEQParam_Gain

      kParametricEQParam_Gain

      Range is from –20 through +20 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Multitype EQ unit.

    Declaration

    Swift

    var kAUNBandEQParam_BypassBand: Int { get } var kAUNBandEQParam_FilterType: Int { get } var kAUNBandEQParam_Frequency: Int { get } var kAUNBandEQParam_Gain: Int { get } var kAUNBandEQParam_Bandwidth: Int { get }

    Objective-C

    enum { kAUNBandEQParam_BypassBand = 1000, kAUNBandEQParam_FilterType = 2000, kAUNBandEQParam_Frequency = 3000, kAUNBandEQParam_Gain = 4000, kAUNBandEQParam_Bandwidth = 5000 };

    Constants

    • kAUNBandEQParam_BypassBand

      kAUNBandEQParam_BypassBand

      Boolean value, with a value of 1 meaning bypass. Default value is 1. Used on the Global scope.

      Available in iOS 5.0 and later

    • kAUNBandEQParam_FilterType

      kAUNBandEQParam_FilterType

      An indexed value using one of the values from Mutitype EQ Unit Filter Types. Default value is kAUNBandEQFilterType_Parametric. Used on the Global scope.

      Available in iOS 5.0 and later

    • kAUNBandEQParam_Frequency

      kAUNBandEQParam_Frequency

      Range is from 20 Hz to less than the Nyquist frequency (half the sample rate). Default value is 1000 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kAUNBandEQParam_Gain

      kAUNBandEQParam_Gain

      Range is from –96 through +24 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kAUNBandEQParam_Bandwidth

      kAUNBandEQParam_Bandwidth

      Range is from 0.05 through 5.0 octaves. Default value is 0.5 octaves. Used on the Global scope.

      Available in iOS 5.0 and later

    Discussion

    The Multitype EQ unit (of subtype kAudioUnitSubType_NBandEQ) provides an equalizer that can be configured as any one of the types described in Mutitype EQ Unit Filter Types.

    Note that the parameter IDs listed correspond to band 0 (zero) of the unit. The parameter IDs for higher bands can be obtained by adding the zero-indexed band number to the corresponding band 0 parameter ID up to the number of bands minus one, where the number of bands is described by the AUNBandEQ property kAUNBandEQProperty_NumberOfBands. For example, the parameter ID corresponding to the filter type of band 4 would be kAUNBandEQParam_FilterType + 3.

  • Values for the kAUNBandEQParam_FilterType parameter of the Multitype EQ (NBandEQ) unit.

    Declaration

    Swift

    var kAUNBandEQFilterType_Parametric: Int { get } var kAUNBandEQFilterType_2ndOrderButterworthLowPass: Int { get } var kAUNBandEQFilterType_2ndOrderButterworthHighPass: Int { get } var kAUNBandEQFilterType_ResonantLowPass: Int { get } var kAUNBandEQFilterType_ResonantHighPass: Int { get } var kAUNBandEQFilterType_BandPass: Int { get } var kAUNBandEQFilterType_BandStop: Int { get } var kAUNBandEQFilterType_LowShelf: Int { get } var kAUNBandEQFilterType_HighShelf: Int { get } var kAUNBandEQFilterType_ResonantLowShelf: Int { get } var kAUNBandEQFilterType_ResonantHighShelf: Int { get } var kNumAUNBandEQFilterTypes: Int { get }

    Objective-C

    enum { kAUNBandEQFilterType_Parametric = 0, kAUNBandEQFilterType_2ndOrderButterworthLowPass = 1, kAUNBandEQFilterType_2ndOrderButterworthHighPass = 2, kAUNBandEQFilterType_ResonantLowPass = 3, kAUNBandEQFilterType_ResonantHighPass = 4, kAUNBandEQFilterType_BandPass = 5, kAUNBandEQFilterType_BandStop = 6, kAUNBandEQFilterType_LowShelf = 7, kAUNBandEQFilterType_HighShelf = 8, kAUNBandEQFilterType_ResonantLowShelf = 9, kAUNBandEQFilterType_ResonantHighShelf = 10, kNumAUNBandEQFilterTypes = 11 };

    Constants

    • kAUNBandEQFilterType_Parametric

      kAUNBandEQFilterType_Parametric

      Parametric filter based on the Butterworth analog prototype.

      Uses parameterization where the bandwidth is specified as the relationship of the upper band edge frequency to the lower band edge frequency in octaves, where the upper and lower band edge frequencies are the respective frequencies above and below the center frequency at which the gain is equal to half the peak gain.

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_2ndOrderButterworthLowPass

      kAUNBandEQFilterType_2ndOrderButterworthLowPass

      Simple Butterworth 2nd order low pass filter.

      The only application parameter when using this filter type is kAUNBandEQParam_Frequency (–3 dB cutoff frequency).

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_2ndOrderButterworthHighPass

      kAUNBandEQFilterType_2ndOrderButterworthHighPass

      Simple Butterworth 2nd order high pass filter.

      The only application parameter when using this filter type is kAUNBandEQParam_Frequency (–3 dB cutoff frequency).

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_ResonantLowPass

      kAUNBandEQFilterType_ResonantLowPass

      Low pass filter with resonance support (via bandwidth parameter).

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_ResonantHighPass

      kAUNBandEQFilterType_ResonantHighPass

      High pass filter with resonance support (via bandwidth parameter).

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_BandPass

      kAUNBandEQFilterType_BandPass

      Bandpass filter.

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_BandStop

      kAUNBandEQFilterType_BandStop

      Band stop (also called notch) filter.

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_LowShelf

      kAUNBandEQFilterType_LowShelf

      Low shelf filter.

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_HighShelf

      kAUNBandEQFilterType_HighShelf

      High shelf filter.

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_ResonantLowShelf

      kAUNBandEQFilterType_ResonantLowShelf

      Low shelf filter with resonance support (via bandwidth parameter).

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kAUNBandEQFilterType_ResonantHighShelf

      kAUNBandEQFilterType_ResonantHighShelf

      High shelf filter with resonance support (via bandwidth parameter).

      Applicable parameters when using this filter type:

      Available in iOS 5.0 and later

    • kNumAUNBandEQFilterTypes

      kNumAUNBandEQFilterTypes

      The available filter types.

      Available in iOS 5.0 and later

  • Parameters for the Dynamics Processor unit.

    Declaration

    Swift

    var kDynamicsProcessorParam_Threshold: Int { get } var kDynamicsProcessorParam_HeadRoom: Int { get } var kDynamicsProcessorParam_ExpansionRatio: Int { get } var kDynamicsProcessorParam_ExpansionThreshold: Int { get } var kDynamicsProcessorParam_AttackTime: Int { get } var kDynamicsProcessorParam_ReleaseTime: Int { get } var kDynamicsProcessorParam_MasterGain: Int { get } var kDynamicsProcessorParam_CompressionAmount: Int { get } var kDynamicsProcessorParam_InputAmplitude: Int { get } var kDynamicsProcessorParam_OutputAmplitude: Int { get }

    Objective-C

    enum { kDynamicsProcessorParam_Threshold = 0, kDynamicsProcessorParam_HeadRoom = 1, kDynamicsProcessorParam_ExpansionRatio = 2, kDynamicsProcessorParam_ExpansionThreshold = 3, kDynamicsProcessorParam_AttackTime = 4, kDynamicsProcessorParam_ReleaseTime = 5, kDynamicsProcessorParam_MasterGain = 6, kDynamicsProcessorParam_CompressionAmount = 1000, kDynamicsProcessorParam_InputAmplitude = 2000, kDynamicsProcessorParam_OutputAmplitude = 3000 };

    Constants

    • kDynamicsProcessorParam_Threshold

      kDynamicsProcessorParam_Threshold

      Range is from –40 through +20 dB. Default value is –20 dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_HeadRoom

      kDynamicsProcessorParam_HeadRoom

      Range is from 0.1 through 40 dB. Default value is 5 dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_ExpansionRatio

      kDynamicsProcessorParam_ExpansionRatio

      Range is from 1.0 through 50.0. Default value is 2. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_ExpansionThreshold

      kDynamicsProcessorParam_ExpansionThreshold

      Units are dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_AttackTime

      kDynamicsProcessorParam_AttackTime

      Range is from 0.0001 through 0.2 seconds. Default value is 0.001 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_ReleaseTime

      kDynamicsProcessorParam_ReleaseTime

      Range is from 0.01 through 3.0 seconds. Default value is 0.05 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_MasterGain

      kDynamicsProcessorParam_MasterGain

      Range is from –40 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_CompressionAmount

      kDynamicsProcessorParam_CompressionAmount

      Units are dB. Used on the Global scope. Read-only.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_InputAmplitude

      kDynamicsProcessorParam_InputAmplitude

      Units are dB. Used on the Global scope. Read-only.

      Available in iOS 5.0 and later

    • kDynamicsProcessorParam_OutputAmplitude

      kDynamicsProcessorParam_OutputAmplitude

      Units are dB. Used on the Global scope. Read-only.

      Available in iOS 5.0 and later

  • Parameters for the Peak Limiter unit.

    Declaration

    Swift

    var kLimiterParam_AttackTime: Int { get } var kLimiterParam_DecayTime: Int { get } var kLimiterParam_PreGain: Int { get }

    Objective-C

    enum { kLimiterParam_AttackTime = 0, kLimiterParam_DecayTime = 1, kLimiterParam_PreGain = 2 };

    Constants

    • kLimiterParam_AttackTime

      kLimiterParam_AttackTime

      Range is from 0.001 through 0.03 seconds. Default value is 0.012 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kLimiterParam_DecayTime

      kLimiterParam_DecayTime

      Range is from 0.001 through 0.06 seconds. Default value is 0.024 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kLimiterParam_PreGain

      kLimiterParam_PreGain

      Range is from –40 through +40 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Reverb unit.

    Declaration

    Swift

    var kReverb2Param_DryWetMix: Int { get } var kReverb2Param_Gain: Int { get } var kReverb2Param_MinDelayTime: Int { get } var kReverb2Param_MaxDelayTime: Int { get } var kReverb2Param_DecayTimeAt0Hz: Int { get } var kReverb2Param_DecayTimeAtNyquist: Int { get } var kReverb2Param_RandomizeReflections: Int { get }

    Objective-C

    enum { kReverb2Param_DryWetMix = 0, kReverb2Param_Gain = 1, kReverb2Param_MinDelayTime = 2, kReverb2Param_MaxDelayTime = 3, kReverb2Param_DecayTimeAt0Hz = 4, kReverb2Param_DecayTimeAtNyquist = 5, kReverb2Param_RandomizeReflections = 6, };

    Constants

    • kReverb2Param_DryWetMix

      kReverb2Param_DryWetMix

      Range is from 0 through 100%. Default value is 100% (full reverb). Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_Gain

      kReverb2Param_Gain

      Range is from –20 through +20 dB. Default value is 0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_MinDelayTime

      kReverb2Param_MinDelayTime

      Range is from 0.0001 through 1.0 seconds. Default value is 0.008 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_MaxDelayTime

      kReverb2Param_MaxDelayTime

      Range is from 0.0001 through 1.0 seconds. Default value is 0.050 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_DecayTimeAt0Hz

      kReverb2Param_DecayTimeAt0Hz

      Range is from 0.001 through 20.0 seconds. Default value is 1.0 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_DecayTimeAtNyquist

      kReverb2Param_DecayTimeAtNyquist

      Range is from 0.001 through 20.0 seconds. Default value is 0.5 s. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverb2Param_RandomizeReflections

      kReverb2Param_RandomizeReflections

      Range is from 1 through 1000 (unitless). Used on the Global scope.

      Available in iOS 5.0 and later

  • Additional reverb parameters.

    Declaration

    Swift

    var kReverbParam_FilterFrequency: Int { get } var kReverbParam_FilterBandwidth: Int { get } var kReverbParam_FilterGain: Int { get }

    Objective-C

    enum { kReverbParam_FilterFrequency = 14, kReverbParam_FilterBandwidth = 15, kReverbParam_FilterGain = 16 };

    Constants

    • kReverbParam_FilterFrequency

      kReverbParam_FilterFrequency

      Range is from 10.0 through 20000.0 Hz. Default value is 800.0 Hz. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverbParam_FilterBandwidth

      kReverbParam_FilterBandwidth

      Range is from 0.05 through 4.0 octaves. Default value is 3.0 octaves. Used on the Global scope.

      Available in iOS 5.0 and later

    • kReverbParam_FilterGain

      kReverbParam_FilterGain

      Range is from –18.0 through +18.0 dB. Default value is 0.0 dB. Used on the Global scope.

      Available in iOS 5.0 and later

  • Parameters for the Varispeed unit.

    Declaration

    Swift

    var kVarispeedParam_PlaybackRate: Int { get } var kVarispeedParam_PlaybackCents: Int { get }

    Objective-C

    enum { kVarispeedParam_PlaybackRate = 0, kVarispeedParam_PlaybackCents = 1 };

    Constants

    • kVarispeedParam_PlaybackRate

      kVarispeedParam_PlaybackRate

      Available in iOS 5.0 and later

    • kVarispeedParam_PlaybackCents

      kVarispeedParam_PlaybackCents

      Available in iOS 5.0 and later

  • Parameters for instrument units.

    Declaration

    Swift

    var kAUGroupParameterID_Volume: Int { get } var kAUGroupParameterID_Sustain: Int { get } var kAUGroupParameterID_AllNotesOff: Int { get } var kAUGroupParameterID_ModWheel: Int { get } var kAUGroupParameterID_PitchBend: Int { get } var kAUGroupParameterID_AllSoundOff: Int { get } var kAUGroupParameterID_ResetAllControllers: Int { get } var kAUGroupParameterID_Pan: Int { get } var kAUGroupParameterID_Foot: Int { get } var kAUGroupParameterID_ChannelPressure: Int { get } var kAUGroupParameterID_KeyPressure: Int { get } var kAUGroupParameterID_Expression: Int { get } var kAUGroupParameterID_DataEntry: Int { get } var kAUGroupParameterID_Volume_LSB: Int { get } var kAUGroupParameterID_ModWheel_LSB: Int { get } var kAUGroupParameterID_Pan_LSB: Int { get } var kAUGroupParameterID_Foot_LSB: Int { get } var kAUGroupParameterID_Expression_LSB: Int { get } var kAUGroupParameterID_DataEntry_LSB: Int { get } var kAUGroupParameterID_KeyPressure_FirstKey: Int { get } var kAUGroupParameterID_KeyPressure_LastKey: Int { get }

    Objective-C

    enum { kAUGroupParameterID_Volume = 7, // value 0 < 128 kAUGroupParameterID_Sustain = 64, // value 0-63 (off ), 64-127 (on ) kAUGroupParameterID_AllNotesOff = 123, // value ignored kAUGroupParameterID_ModWheel = 1, // value 0 < 128 kAUGroupParameterID_PitchBend = 0xE0 , // value -8192 - 8191 kAUGroupParameterID_AllSoundOff = 120, // value ignored kAUGroupParameterID_ResetAllControllers = 121, // value ignored kAUGroupParameterID_Pan = 10, // value 0 < 128 kAUGroupParameterID_Foot = 4, // value 0 < 128 kAUGroupParameterID_ChannelPressure = 0xD0 , // value 0 < 128 kAUGroupParameterID_KeyPressure = 0xA0 , // values 0 < 128 kAUGroupParameterID_Expression = 11, // value 0 < 128 kAUGroupParameterID_DataEntry = 6, // value 0 < 128 kAUGroupParameterID_Volume_LSB = kAUGroupParameterID_Volume + 32, // value 0 < 128 kAUGroupParameterID_ModWheel_LSB = kAUGroupParameterID_ModWheel + 32, // value 0 < 128 kAUGroupParameterID_Pan_LSB = kAUGroupParameterID_Pan + 32, // value 0 < 128 kAUGroupParameterID_Foot_LSB = kAUGroupParameterID_Foot + 32, // value 0 < 128 kAUGroupParameterID_Expression_LSB = kAUGroupParameterID_Expression + 32, // value 0 < 128 kAUGroupParameterID_DataEntry_LSB = kAUGroupParameterID_DataEntry + 32, // value 0 < 128 kAUGroupParameterID_KeyPressure_FirstKey = 256, // value 0 < 128 kAUGroupParameterID_KeyPressure_LastKey = 383 // value 0 < 128 };

    Constants

    • kAUGroupParameterID_Volume

      kAUGroupParameterID_Volume

      The output volume of the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Sustain

      kAUGroupParameterID_Sustain

      The sustain characteristic for notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_AllNotesOff

      kAUGroupParameterID_AllNotesOff

      Unused.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_ModWheel

      kAUGroupParameterID_ModWheel

      The amount of mod wheel effect to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_PitchBend

      kAUGroupParameterID_PitchBend

      The amount of pitch bend to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_AllSoundOff

      kAUGroupParameterID_AllSoundOff

      Unused.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_ResetAllControllers

      kAUGroupParameterID_ResetAllControllers

      Unused.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Pan

      kAUGroupParameterID_Pan

      The left/right pan position for notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Foot

      kAUGroupParameterID_Foot

      The amount of foot pedal effect to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_ChannelPressure

      kAUGroupParameterID_ChannelPressure

      The amount of channel pressure to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_KeyPressure

      kAUGroupParameterID_KeyPressure

      The amount of key pressure to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Expression

      kAUGroupParameterID_Expression

      The expression value to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_DataEntry

      kAUGroupParameterID_DataEntry

      The data entry value to apply to notes produced by the audio unit.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Volume_LSB

      kAUGroupParameterID_Volume_LSB

      The least significant byte portion of the kAUGroupParameterID_Volume parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_ModWheel_LSB

      kAUGroupParameterID_ModWheel_LSB

      The least significant byte portion of the kAUGroupParameterID_ModWheel parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Pan_LSB

      kAUGroupParameterID_Pan_LSB

      The least significant byte portion of the kAUGroupParameterID_Pan parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Foot_LSB

      kAUGroupParameterID_Foot_LSB

      The least significant byte portion of the kAUGroupParameterID_Foot parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_Expression_LSB

      kAUGroupParameterID_Expression_LSB

      The least significant byte portion of the kAUGroupParameterID_Expression parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_DataEntry_LSB

      kAUGroupParameterID_DataEntry_LSB

      The least significant byte portion of the kAUGroupParameterID_DataEntry parameter value.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_KeyPressure_FirstKey

      kAUGroupParameterID_KeyPressure_FirstKey

      The first key key pressure.

      Available in iOS 5.0 and later

    • kAUGroupParameterID_KeyPressure_LastKey

      kAUGroupParameterID_KeyPressure_LastKey

      The last key key pressure.

      Available in iOS 5.0 and later

    Discussion

    These parameters correspond to the Group scope for standard MIDI Controllers.

    Group scope parameter IDs from 0 through 511 are reserved for mapping MIDI controllers.

  • Declaration

    Swift

    var kTimePitchParam_Rate: Int { get }

    Objective-C

    enum { kTimePitchParam_Rate = 0, kTimePitchParam_Pitch = 1, kTimePitchParam_EffectBlend = 2 // only for the AUPitch unit };

    Constants

    • kTimePitchParam_Rate

      kTimePitchParam_Rate

      Available in iOS 2.0 and later

    • kTimePitchParam_Pitch

      kTimePitchParam_Pitch

      Available in iOS 2.0 through iOS 2.0

    • kTimePitchParam_EffectBlend

      kTimePitchParam_EffectBlend

      Available in iOS 2.0 through iOS 2.0

    Discussion

    These parameters are not used in iPhone OS.

  • Declaration

    Swift

    var kHALOutputParam_Volume: Int { get }

    Objective-C

    enum { kHALOutputParam_Volume = 14 };

    Constants

    • kHALOutputParam_Volume

      kHALOutputParam_Volume

      Applies to the audio unit global scope. Linear gain from 0 through 1. Default value is 1.

      Available in iOS 2.0 and later

    Discussion