portaudio

package module
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 Go to latest Published: Jul 9, 2023 License: MIT Imports: 8 Imported by: 360

README

portaudio

This package provides an interface to the PortAudio audio I/O library. See the package documentation for details.

To build this package you must first have the PortAudio development headers and libraries installed. Some systems provide a package for this; e.g., on Ubuntu you would want to run apt-get install portaudio19-dev. On other systems you might have to install from source.

Thanks to sqweek for motivating and contributing to host API and device enumeration.

Documentation

Overview

Package portaudio applies Go bindings to the PortAudio library.

For the most part, these bindings parallel the underlying PortAudio API; please refer to http://www.portaudio.com/docs.html for details. Differences introduced by the bindings are documented here:

Instead of passing a flag to OpenStream, audio sample formats are inferred from the signature of the stream callback or, for a blocking stream, from the types of the buffers. See the StreamCallback and Buffer types for details.

Blocking I/O: Read and Write do not accept buffer arguments; instead they use the buffers (or pointers to buffers) provided to OpenStream. The number of samples to read or write is determined by the size of the buffers.

The StreamParameters struct combines parameters for both the input and the output device as well as the sample rate, buffer size, and flags.

Index

Constants

View Source 
const FramesPerBufferUnspecified = C.paFramesPerBufferUnspecified

FramesPerBufferUnspecified ...

Variables

This section is empty.

Functions

func Initialize 

func Initialize() error

Initialize initializes internal data structures and prepares underlying host APIs for use. With the exception of Version(), VersionText(), and ErrorText(), this function MUST be called before using any other PortAudio API functions.

If Initialize() is called multiple times, each successful call must be matched with a corresponding call to Terminate(). Pairs of calls to Initialize()/Terminate() may overlap, and are not required to be fully nested.

Note that if Initialize() returns an error code, Terminate() should NOT be called.

func IsFormatSupported 

func IsFormatSupported(p StreamParameters, args ...interface{}) error

IsFormatSupported Returns nil if the format is supported, otherwise an error. The args parameter has the same meaning as in OpenStream.

func Terminate 

func Terminate() error

Terminate deallocates all resources allocated by PortAudio since it was initialized by a call to Initialize().

In cases where Initialize() has been called multiple times, each call must be matched with a corresponding call to Pa_Terminate(). The final matching call to Pa_Terminate() will automatically close any PortAudio streams that are still open..

Terminate MUST be called before exiting a program which uses PortAudio. Failure to do so may result in serious resource leaks, such as audio devices not being available until the next reboot.

func Version 

func Version() int

Version returns the release number of PortAudio.

func VersionText 

func VersionText() string

VersionText returns the textual description of the PortAudio release.

Types

type Buffer 

type Buffer interface{}

Buffer exists for documentation purposes only.

A Buffer is of the form [][]SampleType or []SampleType where SampleType is float32, int32, Int24, int16, int8, or uint8.

In the first form, channels are non-interleaved: len(buf) == numChannels and len(buf[i]) == framesPerBuffer

In the second form, channels are interleaved: len(buf) == numChannels * framesPerBuffer

type DeviceInfo 

type DeviceInfo struct {
	Name                     string
	MaxInputChannels         int
	MaxOutputChannels        int
	DefaultLowInputLatency   time.Duration
	DefaultLowOutputLatency  time.Duration
	DefaultHighInputLatency  time.Duration
	DefaultHighOutputLatency time.Duration
	DefaultSampleRate        float64
	HostApi                  *HostApiInfo
	// contains filtered or unexported fields
}

DeviceInfo contains information for an audio device.

func DefaultInputDevice 

func DefaultInputDevice() (*DeviceInfo, error)

DefaultInputDevice returns information for the default input device on the system.

func DefaultOutputDevice 

func DefaultOutputDevice() (*DeviceInfo, error)

DefaultOutputDevice returns information for the default output device on the system.

func Devices 

func Devices() ([]*DeviceInfo, error)

Devices returns information for all available devices on the system.

type Error 

type Error C.PaError

Error wraps over PaError. 

const (
	NotInitialized                        Error = C.paNotInitialized
	InvalidChannelCount                   Error = C.paInvalidChannelCount
	InvalidSampleRate                     Error = C.paInvalidSampleRate
	InvalidDevice                         Error = C.paInvalidDevice
	InvalidFlag                           Error = C.paInvalidFlag
	SampleFormatNotSupported              Error = C.paSampleFormatNotSupported
	BadIODeviceCombination                Error = C.paBadIODeviceCombination
	InsufficientMemory                    Error = C.paInsufficientMemory
	BufferTooBig                          Error = C.paBufferTooBig
	BufferTooSmall                        Error = C.paBufferTooSmall
	NullCallback                          Error = C.paNullCallback
	BadStreamPtr                          Error = C.paBadStreamPtr
	TimedOut                              Error = C.paTimedOut
	InternalError                         Error = C.paInternalError
	DeviceUnavailable                     Error = C.paDeviceUnavailable
	IncompatibleHostApiSpecificStreamInfo Error = C.paIncompatibleHostApiSpecificStreamInfo
	StreamIsStopped                       Error = C.paStreamIsStopped
	StreamIsNotStopped                    Error = C.paStreamIsNotStopped
	InputOverflowed                       Error = C.paInputOverflowed
	OutputUnderflowed                     Error = C.paOutputUnderflowed
	HostApiNotFound                       Error = C.paHostApiNotFound
	InvalidHostApi                        Error = C.paInvalidHostApi
	CanNotReadFromACallbackStream         Error = C.paCanNotReadFromACallbackStream
	CanNotWriteToACallbackStream          Error = C.paCanNotWriteToACallbackStream
	CanNotReadFromAnOutputOnlyStream      Error = C.paCanNotReadFromAnOutputOnlyStream
	CanNotWriteToAnInputOnlyStream        Error = C.paCanNotWriteToAnInputOnlyStream
	IncompatibleStreamHostApi             Error = C.paIncompatibleStreamHostApi
	BadBufferPtr                          Error = C.paBadBufferPtr
	NoDefaultInputDevice                  Error = -1
	NoDefaultOutputDevice                 Error = -2
)

PortAudio Errors.

func (Error) Error 

func (err Error) Error() string

type HostApiInfo 

type HostApiInfo struct {
	Type                HostApiType
	Name                string
	DefaultInputDevice  *DeviceInfo
	DefaultOutputDevice *DeviceInfo
	Devices             []*DeviceInfo
}

HostApiInfo contains information for a HostApi.

func DefaultHostApi 

func DefaultHostApi() (*HostApiInfo, error)

DefaultHostApi returns information of the default HostApi available on the system.

The default host API will be the lowest common denominator host API on the current platform and is unlikely to provide the best performance.

func HostApi 

func HostApi(apiType HostApiType) (*HostApiInfo, error)

HostApi returns information for a requested HostApiType.

func HostApis 

func HostApis() ([]*HostApiInfo, error)

HostApis returns all information available for HostApis.

type HostApiType 

type HostApiType int

HostApiType maps ints to HostApi modes. 

const (
	InDevelopment   HostApiType = C.paInDevelopment
	DirectSound     HostApiType = C.paDirectSound
	MME             HostApiType = C.paMME
	ASIO            HostApiType = C.paASIO
	SoundManager    HostApiType = C.paSoundManager
	CoreAudio       HostApiType = C.paCoreAudio
	OSS             HostApiType = C.paOSS
	ALSA            HostApiType = C.paALSA
	AL              HostApiType = C.paAL
	BeOS            HostApiType = C.paBeOS
	WDMkS           HostApiType = C.paWDMKS
	JACK            HostApiType = C.paJACK
	WASAPI          HostApiType = C.paWASAPI
	AudioScienceHPI HostApiType = C.paAudioScienceHPI
)

PortAudio Api types.

func (HostApiType) String 

func (t HostApiType) String() string

type Int24 

type Int24 [3]byte

Int24 holds the bytes of a 24-bit signed integer in native byte order.

func (*Int24) PutInt32 

func (i24 *Int24) PutInt32(i32 int32)

PutInt32 puts the three most significant bytes of i32 into i24.

type Stream 

type Stream struct {
	// contains filtered or unexported fields
}

Stream provides access to audio hardware represented by one or more PaDevices. Depending on the underlying Host API, it may be possible to open multiple streams using the same device, however this behavior is implementation defined.

Portable applications should assume that a Device may be simultaneously used by at most one Stream.

func OpenDefaultStream 

func OpenDefaultStream(numInputChannels, numOutputChannels int, sampleRate float64, framesPerBuffer int, args ...interface{}) (*Stream, error)

OpenDefaultStream is a simplified version of OpenStream that opens the default input and/or output devices.

The args parameter has the same meaning as in OpenStream.

func OpenStream 

func OpenStream(p StreamParameters, args ...interface{}) (*Stream, error)

OpenStream creates an instance of a Stream.

For an input- or output-only stream, p.Output.Device or p.Input.Device must be nil, respectively.

The args may consist of either a single StreamCallback or, for a blocking stream, two Buffers or pointers to Buffers.

For an input- or output-only stream, one of the Buffer args may be omitted.

func (*Stream) Abort 

func (s *Stream) Abort() error

Abort terminates audio processing immediately without waiting for pending buffers to complete.

func (*Stream) AvailableToRead 

func (s *Stream) AvailableToRead() (int, error)

AvailableToRead returns the number of frames that can be read from the stream without waiting.

func (*Stream) AvailableToWrite 

func (s *Stream) AvailableToWrite() (int, error)

AvailableToWrite returns the number of frames that can be written from the stream without waiting.

func (*Stream) Close 

func (s *Stream) Close() error

Close terminates the stream.

func (*Stream) CpuLoad 

func (s *Stream) CpuLoad() float64

CpuLoad returns the CPU usage information for the specified stream, where 0.0 is 0% usage and 1.0 is 100% usage.

The "CPU Load" is a fraction of total CPU time consumed by a callback stream's audio processing routines including, but not limited to the client supplied stream callback.

This function does not work with blocking read/write streams.

This function may be called from the stream callback function or the application.

func (*Stream) Info 

func (s *Stream) Info() *StreamInfo

Info returns information about the Stream instance.

func (*Stream) Read 

func (s *Stream) Read() error

Read uses the buffer provided to OpenStream. The number of samples to read is determined by the size of the buffer.

func (*Stream) Start 

func (s *Stream) Start() error

Start commences audio processing.

func (*Stream) Stop 

func (s *Stream) Stop() error

Stop terminates audio processing. It waits until all pending audio buffers have been played before it returns.

func (*Stream) Time 

func (s *Stream) Time() time.Duration

Time returns the current time in seconds for a lifespan of a stream. Starting and stopping the stream does not affect the passage of time.

func (*Stream) Write 

func (s *Stream) Write() error

Write uses the buffer provided to OpenStream. The number of samples to write is determined by the size of the buffer.

type StreamCallback 

type StreamCallback interface{}

StreamCallback exists for documentation purposes only.

A StreamCallback is a func whose signature resembles 

func(in Buffer, out Buffer, timeInfo StreamCallbackTimeInfo, flags StreamCallbackFlags)

where the final one or two parameters may be omitted. For an input- or output-only stream, one of the Buffer parameters may also be omitted. The two Buffer types may be different.

type StreamCallbackFlags 

type StreamCallbackFlags C.PaStreamCallbackFlags

StreamCallbackFlags are flag bit constants for the statusFlags to StreamCallback. 

const (
	// In a stream opened with FramesPerBufferUnspecified,
	// InputUnderflow indicates that input data is all silence (zeros)
	// because no real data is available.
	//
	// In a stream opened without FramesPerBufferUnspecified,
	// InputUnderflow indicates that one or more zero samples have been inserted
	// into the input buffer to compensate for an input underflow.
	InputUnderflow StreamCallbackFlags = C.paInputUnderflow

	// In a stream opened with FramesPerBufferUnspecified,
	// indicates that data prior to the first sample of the
	// input buffer was discarded due to an overflow, possibly
	// because the stream callback is using too much CPU time.
	//
	// Otherwise indicates that data prior to one or more samples
	// in the input buffer was discarded.
	InputOverflow StreamCallbackFlags = C.paInputOverflow

	// Indicates that output data (or a gap) was inserted,
	// possibly because the stream callback is using too much CPU time.
	OutputUnderflow StreamCallbackFlags = C.paOutputUnderflow

	// Indicates that output data will be discarded because no room is available.
	OutputOverflow StreamCallbackFlags = C.paOutputOverflow

	// Some of all of the output data will be used to prime the stream,
	// input data may be zero.
	PrimingOutput StreamCallbackFlags = C.paPrimingOutput
)

PortAudio stream callback flags.

type StreamCallbackTimeInfo 

type StreamCallbackTimeInfo struct {
	InputBufferAdcTime, CurrentTime, OutputBufferDacTime time.Duration
}

StreamCallbackTimeInfo contains timing information for the buffers passed to the stream callback.

type StreamDeviceParameters 

type StreamDeviceParameters struct {
	Device   *DeviceInfo
	Channels int
	Latency  time.Duration
}

StreamDeviceParameters specifies parameters for one device (either input or output) in a stream. A nil Device indicates that no device is to be used -- i.e., for an input- or output-only stream.

type StreamFlags 

type StreamFlags C.PaStreamFlags

StreamFlags ... 

const (
	NoFlag                                StreamFlags = C.paNoFlag
	ClipOff                               StreamFlags = C.paClipOff
	DitherOff                             StreamFlags = C.paDitherOff
	NeverDropInput                        StreamFlags = C.paNeverDropInput
	PrimeOutputBuffersUsingStreamCallback StreamFlags = C.paPrimeOutputBuffersUsingStreamCallback
	PlatformSpecificFlags                 StreamFlags = C.paPlatformSpecificFlags
)

type StreamInfo 

type StreamInfo struct {
	InputLatency, OutputLatency time.Duration
	SampleRate                  float64
}

StreamInfo contains information about the stream.

type StreamParameters 

type StreamParameters struct {
	Input, Output   StreamDeviceParameters
	SampleRate      float64
	FramesPerBuffer int
	Flags           StreamFlags
}

StreamParameters includes all parameters required to open a stream except for the callback or buffers.

func HighLatencyParameters 

func HighLatencyParameters(in, out *DeviceInfo) (p StreamParameters)

HighLatencyParameters are mono in, stereo out (if supported), high latency, the smaller of the default sample rates of the two devices, and FramesPerBufferUnspecified. One of the devices may be nil.

func LowLatencyParameters 

func LowLatencyParameters(in, out *DeviceInfo) (p StreamParameters)

LowLatencyParameters are mono in, stereo out (if supported), low latency, the larger of the default sample rates of the two devices, and FramesPerBufferUnspecified. One of the devices may be nil.

type UnanticipatedHostError 

type UnanticipatedHostError struct {
	HostApiType HostApiType
	Code        int
	Text        string
}

UnanticipatedHostError contains details for ApiHost related errors.

func (UnanticipatedHostError) Error 

func (err UnanticipatedHostError) Error() string

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