Koala Noise Suppression
iOS API

API Reference for the Koala iOS SDK (Cocoapods) .

Koala

public class Koala { }

Class for the Koala Noise Suppression engine.

Koala can be initialized using the class constructor. Resources should be cleaned when you are done using the delete() method.

Koala.delaySample

public var delaySample: UInt32

Delay in samples. If the input and output of consecutive calls to process() are viewed as two contiguous streams of audio data, this delay specifies the time shift between the input and output stream.

Koala.frameLength

public static let frameLength: UInt32

The number of audio samples per frame that Koala accepts.

Koala.sampleRate

public static let sampleRate: UInt32

The audio sample rate that Koala accepts.

Koala.version

public static let version: String

The Koala library version string.

Koala.getAvailableDevices()

public static func getAvailableDevices() throws -> [String]

Retrieves a list of devices that can be specified when constructing Koala.

Returns

• [String] : An array of available devices.

Throws

• KoalaError: If an error occurs while retrieving the devices.

Koala.init()

public init(
    accessKey: String,
    modelPath: String? = nil,
    device: String? = nil) throws

init method for Koala Noise Suppression Engine.

Parameters

• access_key String : AccessKey obtained from Picovoice Console.
• modelPath String? : Absolute path to file containing model parameters (.pv).
• device String? : String representation of the device (e.g., CPU or GPU) to use. If set to best, the most suitable device is selected automatically. If set to gpu, the engine uses the first available GPU device. To select a specific GPU device, set this argument to gpu:${GPU_INDEX}, where ${GPU_INDEX} is the index of the target GPU. If set to cpu, the engine will run on the CPU with the default number of threads. To specify the number of threads, set this argument to cpu:${NUM_THREADS}, where ${NUM_THREADS} is the desired number of threads.

Returns

• Koala : An instance of Koala Noise Suppression Engine.

Throws

• KoalaError

public convenience init(accessKey: String, modelURL: URL) throws

Parameters

• access_key String : AccessKey obtained from Picovoice Console.
• modelURL URL : URL to file containing model parameters (.pv).

Returns

• Koala : An instance of Koala Noise Suppression Engine.

Throws

• KoalaError

Koala.delete()

public func delete()

Releases resources acquired by Koala.

Koala.process()

public func process(pcm: [Int16]) throws -> [Int16]

Processes a frame of audio and returns delayed enhanced audio.

The number of samples per frame can be attained from frameLength. The incoming audio needs to have a sample rate equal to sampleRate and be 16-bit linearly-encoded. Koala operates on single-channel audio. Consecutive calls to process() must provide consecutive frames of audio from the same source, unless reset() has been called in between.

The output is not directly the enhanced version of the input PCM, but corresponds to samples that were given in previous calls to process(). The delay in samples between the start time of the input frame and the start time of the output frame can be attained from delaySample.

Parameters

• pcm [Int16] : A frame of audio samples.

Returns

• [Int16] : A frame of enhanced audio samples, stored as a sequence of 16-bit linearly-encoded integers.

Throws

• KoalaError

Koala.reset()

public func reset() throws

Marks the end of the audio stream and resets the internal state of the object. Call this function in between calls to process() that do not provide consecutive frames of audio.

KoalaError

public class KoalaError : LocalizedError { }

Error thrown if an error occurs within Koala Noise Suppression engine.

Exceptions

public class KoalaMemoryError : KoalaError {}
public class KoalaIOError : KoalaError {}
public class KoalaInvalidArgumentError : KoalaError {}
public class KoalaStopIterationError : KoalaError {}
public class KoalaKeyError : KoalaError {}
public class KoalaInvalidStateError : KoalaError {}
public class KoalaRuntimeError : KoalaError {}
public class KoalaActivationError : KoalaError {}
public class KoalaActivationLimitError : KoalaError {}
public class KoalaActivationThrottledError : KoalaError {}
public class KoalaActivationRefusedError : KoalaError {}