Class RtAudio

The RtAudio class.

If an API argument is specified but that API isn't supported, a warning is issued and an instance of an available API is created. If available API is found, the routine will abort If no API argument is specified and multiple API support has been compiled, the default order of use is ALSA, (Linux systems) and WASAPI, DS (Windows systems).

Constructors

constructor

Methods

setErrorCallback showWarnings openStream closeStream startStream stopStream abortStream getDevices getDefaultInputDevice getDefaultOutputDevice isStreamOpen isStreamRunning getCurrentApi getStreamLatency getStreamSampleRate getStreamTime setStreamTime getErrorText getVersion getCompiledApi getApiDisplayName getApiName

Constructors

constructor

Methods

setErrorCallback

  • setErrorCallback(errorCallback): void

  • Set a client-defined function that will be invoked when an error or warning occurs

    Parameters

    • errorCallback: ((errType, message) => void)

      the callback

        • (errType, message): void

        • Parameters

          Returns void

    Returns void

showWarnings

  • showWarnings(value): void

  • Specify whether warning messages should be output or not.

    The default behaviour is for warning messages to be output, either to a client-defined error callback function (if specified) or to stderr.

    Parameters

    • value: boolean

      boolean value to use

    Returns void

openStream

  • openStream(outputParameters, inputParameters, format, sampleRate, bufferFrames, options, callback): number

  • A function for opening a stream with the specified parameters.

    Parameters

    • outputParameters: StreamParameters

      Specifies output stream parameters to use when opening a stream, including a device ID, number of channels, and starting channel number. For input-only streams, this argument should be null.

    • inputParameters: StreamParameters

      Specifies input stream parameters to use when opening a stream, including a device ID, number of channels, and starting channel number. For output-only streams, this argument should be null.

    • format: RtAudioFormat

      An RtAudioFormat specifying the desired sample data format.

    • sampleRate: number

      The desired sample rate (sample frames per second).

    • bufferFrames: number

      A value indicating the desired internal buffer size in sample frames. The actual value used by the device is returned from openStream call. A value of zero can be specified, in which case the lowest allowable value is determined.

    • options: StreamOptions

      An optional object containing various global stream options, including a list of OR'ed RtAudioStreamFlags and a suggested number of stream buffers that can be used to control stream latency. More buffers typically result in more robust performance, though at a cost of greater latency. If a value of zero is specified, a system-specific median value is chosen. If the RTAUDIO_MINIMIZE_LATENCY flag bit is set, the lowest allowable value is used. The actual value used is returned from openStream call. The parameter is API dependent.

    • callback: RtAudioCallback

      A function that will be invoked when input data is available and/or output data is needed.

    Returns number

    The actual bufferFrames value used by the device.

closeStream

  • closeStream(): void

  • A function that closes a stream and frees any associated stream memory.

    If a stream is not open, an RTAUDIO_WARNING will be passed to the user-provided errorCallback function (or otherwise printed to stderr).

    Returns void

startStream

  • startStream(): void

  • A function that starts a stream.

    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs during processing. An RTAUDIO_WARNING is returned if a stream is not open or is already running.

    Returns void

stopStream

  • stopStream(): void

  • Stop a stream, allowing any samples remaining in the output queue to be played.

    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs during processing. An RTAUDIO_WARNING is returned if a stream is not open or is already stopped.

    Returns void

abortStream

  • abortStream(): void

  • Stop a stream, discarding any samples remaining in the input/output queue.

    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs during processing. An RTAUDIO_WARNING is returned if a stream is not open or is already stopped.

    Returns void

getDevices

  • getDevices(): DeviceInfo[]

  • A public function that returns a vector of audio devices.

    The ID values returned by this function are used internally by RtAudio to identify a given device. The values themselves are arbitrary and do not correspond to device IDs used by the underlying API (nor are they index values). This function performs a system query of available devices each time it is called, thus supporting devices (dis)connected after instantiation. If no devices are available, the vector size will be zero. If a system error occurs during processing, a warning will be issued.

    Returns DeviceInfo[]

getDefaultInputDevice

  • getDefaultInputDevice(): number

  • A function that returns the ID of the default input device.

    If the underlying audio API does not provide a "default device", the first probed input device ID will be returned. If no devices are available, the return value will be 0 (which is an invalid device identifier).

    Returns number

getDefaultOutputDevice

  • getDefaultOutputDevice(): number

  • A function that returns the ID of the default output device.

    If the underlying audio API does not provide a "default device", the first probed output device ID will be returned. If no devices are available, the return value will be 0 (which is an invalid device identifier).

    Returns number

isStreamOpen

  • isStreamOpen(): boolean

  • Returns true if a stream is open and false if not.

    Returns boolean

isStreamRunning

  • isStreamRunning(): boolean

  • Returns true if the stream is running and false if it is stopped or not open.

    Returns boolean

getCurrentApi

  • getCurrentApi(): number

  • Returns the audio API specifier for the current instance of RtAudio.

    Returns number

getStreamLatency

  • getStreamLatency(): number

  • Returns the internal stream latency in sample frames.

    The stream latency refers to delay in audio input and/or output caused by internal buffering by the audio system and/or hardware. For duplex streams, the returned value will represent the sum of the input and output latencies. If a stream is not open, the returned value will be invalid. If the API does not report latency, the return value will be zero.

    Returns number

getStreamSampleRate

  • getStreamSampleRate(): number

  • Returns actual sample rate in use by the (open) stream.

    On some systems, the sample rate used may be slightly different than that specified in the stream parameters. If a stream is not open, a value of zero is returned.

    Returns number

getStreamTime

  • getStreamTime(): number

  • Returns the number of seconds of processed data since the stream was started.

    The stream time is calculated from the number of sample frames processed by the underlying audio system, which will increment by units of the audio buffer size. It is not an absolute running time. If a stream is not open, the returned value may not be valid.

    Returns number

setStreamTime

  • setStreamTime(): number

  • Set the stream time to a time in seconds greater than or equal to 0.0.

    Returns number

getErrorText

  • getErrorText(): string

  • Retrieve the error message corresponding to the last error or warning condition.

    This function can be used to get a detailed error message when a non-zero RtAudioErrorType is returned by a function. This is the same message sent to the user-provided errorCallback function.

    Returns string

Static getVersion

  • getVersion(): string

  • A static function to determine the current RtAudio version.

    Returns string

Static getCompiledApi

Static getApiDisplayName

  • getApiDisplayName(api): string

  • Return the display name of a specified compiled audio API.

    This obtains a long name used for display purposes. If the API is unknown, this function will return the empty string.

    Parameters

    Returns string

Static getApiName

  • getApiName(api): string

  • Return the name of a specified compiled audio API.

    This obtains a short lower-case name used for identification purposes. This value is guaranteed to remain identical across library versions. If the API is unknown, this function will return the empty string.

    Parameters

    Returns string

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