Table of Contents

Class AsioOut

Namespace
NAudio.Wave
Assembly
NAudio.Asio.dll

ASIO Out Player — the original NAudio 2.x entry point for ASIO playback, recording, and duplex. Implemented in NAudio 3 as a thin facade over AsioDevice: lifecycle, capabilities, drain-on-dispose, and synchronization-context dispatch all flow through that class, while AsioOut keeps its raw IntPtr-based AudioAvailable contract for back-compat consumers.

public class AsioOut : IWavePlayer, IDisposable, IWaveLatency
Inheritance
AsioOut
Implements
Inherited Members
Extension Methods

Remarks

New code should target AsioDevice directly. It exposes per-channel Span<float> for recording and duplex, an explicit Init* mode selection, non-contiguous channel-array routing, and a supported Reinitialize() path for handling DriverResetRequest.

Legacy translations:

Constructors

AsioOut()

Initializes a new instance of the AsioOut class with the first available ASIO Driver.

public AsioOut()

AsioOut(int)

Opens an ASIO output device

public AsioOut(int driverIndex)

Parameters

driverIndex int

Device number (zero based)

AsioOut(string)

Initializes a new instance of the AsioOut class with the driver name.

public AsioOut(string driverName)

Parameters

driverName string

Name of the device.

Properties

AutoStop

Automatically stop when the end of the input stream is reached Disable this if auto-stop is causing hanging issues

public bool AutoStop { get; set; }

Property Value

bool

AverageLatency

The steady-state latency from a sample being queued for output to it being emitted by the audio hardware, assuming uninterrupted playback. This is a property of the buffer configuration and the driver, not of the current playback state.

public TimeSpan AverageLatency { get; }

Property Value

TimeSpan

Remarks

Derived from the driver's reported output latency in samples (ASIOgetLatencies). Computed lazily from cached values — no work is done on the ASIO callback thread.

ChannelOffset

By default the first channel on the input WaveProvider is sent to the first ASIO output. This option sends it to the specified channel number. Warning: make sure you don't set it higher than the number of available output channels - the number of source channels. n.b. Future NAudio may modify this

public int ChannelOffset { get; set; }

Property Value

int

CurrentLatency

The time that has elapsed since the sample currently emerging from the hardware was queued for output. In steady state this is approximately equal to AverageLatency; it differs during start-up, after an underrun, or when the host is filling buffers irregularly. Implementations that cannot meaningfully distinguish from the average are permitted to return AverageLatency.

public TimeSpan CurrentLatency { get; }

Property Value

TimeSpan

Remarks

Returns AverageLatency. ASIO swaps fixed-size buffers at perfectly regular intervals, so the live latency is always equal to the steady-state latency to within half a buffer. Reporting an instrumented value would require timestamping the buffer-switch callback, which we deliberately avoid to keep the real-time path free of extra work.

DriverInputChannelCount

The maximum number of input channels this ASIO driver supports

public int DriverInputChannelCount { get; }

Property Value

int

DriverName

Driver Name

public string DriverName { get; }

Property Value

string

DriverOutputChannelCount

The maximum number of output channels this ASIO driver supports

public int DriverOutputChannelCount { get; }

Property Value

int

FramesPerBuffer

The number of samples per channel, per buffer.

public int FramesPerBuffer { get; }

Property Value

int

HasReachedEnd

A flag to let you know that we have reached the end of the input file Useful if AutoStop is set to false You can monitor this yourself and call Stop when it is true

public bool HasReachedEnd { get; }

Property Value

bool

InputChannelOffset

Input channel offset (used when recording), allowing you to choose to record from just one specific input rather than them all

public int InputChannelOffset { get; set; }

Property Value

int

NumberOfInputChannels

The number of input channels we are currently recording from (Must be less than or equal to DriverInputChannelCount)

public int NumberOfInputChannels { get; }

Property Value

int

NumberOfOutputChannels

The number of output channels we are currently using for playback (Must be less than or equal to DriverOutputChannelCount)

public int NumberOfOutputChannels { get; }

Property Value

int

OutputWaveFormat

The WaveFormat this device is using for playback

public WaveFormat OutputWaveFormat { get; }

Property Value

WaveFormat

PlaybackLatency

Gets the latency (in samples) of the playback driver

public int PlaybackLatency { get; }

Property Value

int

PlaybackState

Playback State

public PlaybackState PlaybackState { get; }

Property Value

PlaybackState

Volume

Sets the volume (1.0 is unity gain) Not supported for ASIO Out. Set the volume on the input stream instead

[Obsolete("this function will be removed in a future NAudio as ASIO does not support setting the volume on the device")]
public float Volume { get; set; }

Property Value

float

Methods

AsioInputChannelName(int)

Get the input channel name

public string AsioInputChannelName(int channel)

Parameters

channel int

channel index (zero based)

Returns

string

channel name

AsioOutputChannelName(int)

Get the output channel name

public string AsioOutputChannelName(int channel)

Parameters

channel int

channel index (zero based)

Returns

string

channel name

Dispose()

Dispose

public void Dispose()

~AsioOut()

Releases unmanaged resources and performs other cleanup operations before the AsioOut is reclaimed by garbage collection.

protected ~AsioOut()

GetDriverNames()

Gets the names of the installed ASIO Driver.

public static string[] GetDriverNames()

Returns

string[]

an array of driver names

Init(IWaveProvider)

Initialises to play

public void Init(IWaveProvider waveProvider)

Parameters

waveProvider IWaveProvider

Source audio source

InitRecordAndPlayback(IWaveProvider, int, int)

Initialises to play, with optional recording

public void InitRecordAndPlayback(IWaveProvider waveProvider, int recordChannels, int recordOnlySampleRate)

Parameters

waveProvider IWaveProvider

Source audio source - set to null for record only

recordChannels int

Number of channels to record

recordOnlySampleRate int

Specify sample rate here if only recording, ignored otherwise

IsSampleRateSupported(int)

Determines whether this driver supports the specified sample rate.

public bool IsSampleRateSupported(int sampleRate)

Parameters

sampleRate int

The samplerate to check.

Returns

bool

true if the specified sample rate is supported otherwise, false.

Pause()

Pauses playback

public void Pause()

Play()

Starts playback

public void Play()

ShowControlPanel()

Shows the control panel

public void ShowControlPanel()

Stop()

Stops playback

public void Stop()

isSupported()

Determines whether ASIO is supported.

public static bool isSupported()

Returns

bool

true if ASIO is supported; otherwise, false.

Events

AudioAvailable

When recording, fires whenever recorded audio is available

public event EventHandler<AsioAudioAvailableEventArgs> AudioAvailable

Event Type

EventHandler<AsioAudioAvailableEventArgs>

DriverResetRequest

Occurs when the driver settings are changed by the user, e.g. in the control panel.

public event EventHandler DriverResetRequest

Event Type

EventHandler

PlaybackStopped

Playback Stopped

public event EventHandler<StoppedEventArgs> PlaybackStopped

Event Type

EventHandler<StoppedEventArgs>
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