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Programmer's Guide

Nulifier edited this page Feb 6, 2018 · 9 revisions

OpenAL Programmer's Guide - Versions 1.0 and 1.1

Table of Contents

About this Document

Introduction

OpenAL is a cross-platform three-dimensional audio API. The API’s primary purpose is to allow an application to position audio sources in a three-dimensional space around a listener, producing reasonable spatialization of the sources for the audio system (headphones, 2.1 speaker output, 5.1 speaker output, etc.) Through extensions, Creative Labs has also enhanced OpenAL with EAX and other capabilities. OpenAL is appropriate for many audio applications, but was designed to be most appropriate for gaming audio.

Intended Audience

This reference guide is most appropriate for a programmer. Experience with C or C++ is not required to learn the concepts in OpenAL, but will make understanding the OpenAL source as well as sample code easier. Since there are several sample applications included with the OpenAL SDKs as well as with the source distribution, it is recommended that interested programmers take advantage of those resources.

Other OpenAL Resources

The two most important resources for additional information on OpenAL are the websites at www.openal.org and http://developer.creative.com. The main OpenAL site hosts the specification, the open source implementations, and sample code. The Creative developer site has a section dedicated to OpenAL with SDKs showing how to use OpenAL as well as various extensions.

Introduction to OpenAL

Use of OpenAL revolves around the use of three fundamental objects – Buffers, Sources, and a Listener. A buffer can be filled with audio data, and can then be attached to a source. The source can then be positioned and played. How the source is heard is determined by its position and orientation relative to the Listener object (there is only one Listener). Creating a number of sources and buffers and a single listener and then updating the positions and orientations of the sources and listener dynamically can present a convincing 3D audio world.

Objects

Here is a diagram showing the fundamental OpenAL objects and their relationships to the context and device objects:

object relationships

When initializing OpenAL, at least one device has to be opened. Within that device, at least one context will be created. Within that context, one listener object is implied, and a multitude of source objects can be created. Each source can have one or more buffers objects attached to it. Buffer objects are not part of a specific context – they are shared among all contexts on one device.

Device Enumeration

The function call to open a device, alcOpenDevice, takes a string as input. The string should contain either the name of a valid OpenAL rendering device, or NULL to request the default device.

On PC Systems, a number of different OpenAL renderering devices may co-exist. For example a “native” renderer specific to the user’s high-end soundcard, and a host-based software fallback renderer. On platforms where multiple renderers can be present, an OpenAL application may require the ability to identify the different devices available, in order to give the end-user a choice of device. OpenAL’s Enumeration extension makes this possible.

The Enumeration extension allows the programmer to retrieve a string listing the names of available devices. It can also provide the name of the default device. Use alcGetString with the device property set to NULL, and the enum property set to ALC_DEVICE_SPECIFIER to get the list of available devices. To get the default device name, pass in NULL and ALC_DEFAULT_DEVICE_SPECIFIER.

The Enumeration extension also works with capture devices – the equivalent values are ALC_CAPTURE_DEVICE_SPECIFIER and ALC_CAPTURE_DEFAULT_DEVICE_SPECIFIER.

The programmer can find out more about the capabilities of each device by querying to see which extensions it supports using alcIsExtensionPresent and alIsExtensionPresent.

Initializing/Exiting

As described above, the first step to initializing OpenAL is to open a device. Once that is successfully done, then a context is opened on that device. Now the fundamental OpenAL objects can be managed – the listener, various sources, and various buffers.

To generate a set of buffers for use, use alGetError to reset the error state, call alGenBuffers to generate the number of buffers desired, and then use alGetError again to detect if an error was generated.

Fill the buffers with PCM data using alBufferData.

To generate a set of sources for use, use alGetError to reset the error state, call alGenSources to generate the number of sources desired, and then use alGetError again to detect if an error was generated.

Buffers are attached to sources using alSourcei.

Once a buffer has been attached to a source, the source can play the buffer using alSourcePlay.

Source and Listener properties can be updated dynamically using property set and get calls such as alGetListenerfv, alListener3f, alSourcei, and alGetSource3f.

Example:

// Initialization
Device = alcOpenDevice(NULL); // select the "preferred device"

if (Device) {
    Context=alcCreateContext(Device,NULL);
    alcMakeContextCurrent(Context);
}

// Check for EAX 2.0 support
g_bEAX = alIsExtensionPresent("EAX2.0");

// Generate Buffers
alGetError(); // clear error code

alGenBuffers(NUM_BUFFERS, g_Buffers);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alGenBuffers :", error);
    return;
}

/ Load test.wav
loadWAVFile("test.wav",&format,&data,&size,&freq,&loop);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alutLoadWAVFile test.wav : ", error);
    alDeleteBuffers(NUM_BUFFERS, g_Buffers);
    return;
}

// Copy test.wav data into AL Buffer 0
alBufferData(g_Buffers[0],format,data,size,freq);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alBufferData buffer 0 : ", error);
    alDeleteBuffers(NUM_BUFFERS, g_Buffers);
    return;
}

// Unload test.wav
unloadWAV(format,data,size,freq);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alutUnloadWAV : ", error);
    alDeleteBuffers(NUM_BUFFERS, g_Buffers);
    return;
}

// Generate Sources
alGenSources(1,source);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alGenSources 1 : ", error);
    return;
}

// Attach buffer 0 to source
alSourcei(source[0], AL_BUFFER, g_Buffers[0]);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alSourcei AL_BUFFER 0 : ", error);
}

// Exit
Context=alcGetCurrentContext();
Device=alcGetContextsDevice(Context);
alcMakeContextCurrent(NULL);
alcDestroyContext(Context);
alcCloseDevice(Device);

Listener properties

For every context, there is automatically one Listener object. The alListener[f, 3f, fv, i] and alGetListener[f, 3f, fv, i] families of functions can be used to set or retrieve the following listener properties:

Property Data Type Description
AL_GAIN f, fv Master gain. Value should be positive
AL_POSITION fv, 3f, iv, 3i X, Y, Z position
AL_VELOCITY fv, 3f, iv, 3i Velocity vector
AL_ORIENTATION fv, iv Orientation expressed as “at” and “up” vectors

Example:

ALfloat listenerPos[]={0.0,0.0,0.0};
ALfloat listenerVel[]={0.0,0.0,0.0};
ALfloat listenerOri[]={0.0,0.0,-1.0, 0.0,1.0,0.0};

// Position ...
alListenerfv(AL_POSITION,listenerPos);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alListenerfv POSITION : ", error);
    return;
}

// Velocity ...
alListenerfv(AL_VELOCITY,listenerVel);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alListenerfv VELOCITY : ", error);
    return;
}

// Orientation ...
alListenerfv(AL_ORIENTATION,listenerOri);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alListenerfv ORIENTATION : ", error);
    return;
}

Buffer Properties

Each buffer generated by alGenBuffers has properties which can be retrieved. The alGetBuffer[f, i] functions can be used to retrieve the following buffer properties:

Property Data Type Description
AL_FREQUENCY i, iv Frequency of buffer in Hz
AL_BITS i, iv Bit depth of buffer
AL_CHANNELS i, iv Number of channels in buffer. > 1 is valid, but buffer won’t be positioned when played
AL_SIZE i, iv Size of buffer in bytes
AL_DATA i, iv Original location where data was copied from generally useless, as was probably freed after buffer creation

Example:

// Retrieve Buffer Frequency
alBufferi(g_Buffers[0], AL_FREQUENCY, iFreq);

Source Properties

Each source generated by alGenSources has properties which can be set or retrieved. The alSource[f, 3f, fv, i] and alGetSource[f, 3f, fv, i] families of functions can be used to set or retrieve the following source properties:

Property Data Type Description
AL_PITCH f, fv Pitch multiplier. Always positive
AL_GAIN f, fv Source gain. Value should be positive
AL_MAX_DISTANCE f, fv, i, iv Used with the Inverse Clamped Distance Model to set the distance where there will no longer be any attenuation of the source
AL_ROLLOFF_FACTOR f, fv, i, iv The rolloff rate for the source. Default is 1.0
AL_REFERENCE_DISTANCE f, fv, i, iv The distance under which the volume for the source would normally drop by half (before being influenced by rolloff factor or AL_MAX_DISTANCE)
AL_MIN_GAIN f, fv The minimum gain for this source
AL_MAX_GAIN f, fv The maximum gain for this source
AL_CONE_OUTER_GAIN f, fv The gain when outside the oriented cone
AL_CONE_INNER_ANGLE f, fv, i, iv The gain when inside the oriented cone
AL_CONE_OUTER_ANGLE f, fv, i, iv Outer angle of the sound cone, in degrees. Default is 360
AL_POSITION fv, 3f X, Y, Z position
AL_VELOCITY fv, 3f Velocity vector
AL_DIRECTION fv, 3f, iv, 3i Direction vector
AL_SOURCE_RELATIVE i, iv Determines if the positions are relative to the listener. Default is AL_FALSE
AL_SOURCE_TYPE i, iv The source type – AL_UNDETERMINED, AL_STATIC, or AL_STREAMING
AL_LOOPING i, iv Turns looping on (AL_TRUE) or off (AL_FALSE)
AL_BUFFER i, iv The ID of the attached buffer
AL_SOURCE_STATE i, iv The state of the source (AL_STOPPED, AL_PLAYING, …)
AL_BUFFERS_QUEUED* i, iv The number of buffers queued on this source
AL_BUFFERS_PROCESSED i, iv The number of buffers in the queue that have been processed
AL_SEC_OFFSET f, fv, i, iv The playback position, expressed in seconds
AL_SAMPLE_OFFSET f, fv, i, iv The playback position, expressed in samples
AL_BYTE_OFFSET f, fv, i, iv The playback position, expressed in bytes

* Read Only (alGetSourcei)

Example:

alGetError(); // clear error state
alSourcef(source[0],AL_PITCH,1.0f);
if ((error = alGetError()) != AL_NO_ERROR)
    DisplayALError("alSourcef 0 AL_PITCH : \n", error);

alGetError(); // clear error state
alSourcef(source[0],AL_GAIN,1.0f);
if ((error = alGetError()) != AL_NO_ERROR)
    DisplayALError("alSourcef 0 AL_GAIN : \n", error);

alGetError(); // clear error state
alSourcefv(source[0],AL_POSITION,source0Pos);
if ((error = alGetError()) != AL_NO_ERROR)
    DisplayALError("alSourcefv 0 AL_POSITION : \n", error);

 alGetError(); // clear error state
alSourcefv(source[0],AL_VELOCITY,source0Vel);
if ((error = alGetError()) != AL_NO_ERROR)
    DisplayALError("alSourcefv 0 AL_VELOCITY : \n", error);

alGetError(); // clear error state
alSourcei(source[0],AL_LOOPING,AL_FALSE);
if ((error = alGetError()) != AL_NO_ERROR)
    DisplayALError("alSourcei 0 AL_LOOPING true: \n", error);

Queuing Buffers on a Source

To continuously stream audio from a source without interruption, buffer queuing is required. To use buffer queuing, the buffers and sources are generated in the normal way, but alSourcei is not used to attach the buffers to the source. Instead, the functions alSourceQueueBuffers and alSourceUnqueueBuffers are used. The program can attach a buffer or a set of buffers to a source using alSourceQueueBuffers, and then call alSourcePlay on that source. While the source is playing, alSourceUnqueueBuffers can be called to remove buffers which have already played. Those buffers can then be filled with new data or discarded. New or refilled buffers can then be attached to the playing source using alSourceQueueBuffers. As long as there is always a new buffer to play in the queue, the source will continue to play.

Although some 1.0 implementations of OpenAL may not enforce the following restrictions on queuing, it is recommended to observe the following additional rules, which do universally apply to 1.1 implementations:

  1. A source that will be used for streaming should not have its first buffer attached using alSourcei – always use alSourceQueueBuffers to attach buffers to streaming sources. Any source can have all buffers detached from it using alSourcei(..., AL_BUFFER, 0), and can then be used for either streaming or non-streaming buffers depending on how data is then attached to the source (with alSourcei or with alSourceQueueBuffers).

  2. All buffers attached to a source using alSourceQueueBuffers should have the same audio format.

Doppler Shift

The Doppler effect depends on the velocities of source and listener relative to the medium, and the propagation speed of sound in that medium. The application might want to emphasize or deemphasize the Doppler effect as physically accurate calculation might not give the desired results. The amount of frequency shift (pitch change) is proportional to the speed of listener and source along their line of sight.

The Doppler effect as implemented by OpenAL is described by the formula below. Effects of the medium (air, water) moving with respect to listener and source are ignored.

  • SS: AL_SPEED_OF_SOUND = speed of sound (default value 343.3)
  • DF: AL_DOPPLER_FACTOR = Doppler factor (default 1.0)
  • vls: Listener velocity scalar (scalar, projected on source-to-listener vector)
  • vss: Source velocity scalar (scalar, projected on source-to-listener vector)
  • f: Frequency of sample
  • f': Effective Doppler shifted frequency
  • SL: Source tt listener vector
  • SV: Source velocity vector
  • LV: Listener velocity vector

Graphic representation of vls and vss: Doppler Graphic

3D Mathematical representation of vls and vss:

There are two API calls global to the current context that provide control of the speed of sound and Doppler factor. AL_DOPPLER_FACTOR is a simple scaling of source and listener velocities to exaggerate or deemphasize the Doppler (pitch) shift resulting from the calculation.

void alDopplerFactor(ALfloat dopplerFactor);

A negative value will result in an AL_INVALID_VALUE error, the command is then ignored. The default value is 1. The current setting can be queried using alGetFloat{v} and AL_DOPPLER_FACTOR.

AL_SPEED_OF_SOUND allows the application to change the reference (propagation) speed used in the Doppler calculation. The source and listener velocities should be expressed in the same units as the speed of sound.

void alSpeedOfSound(ALfloat speed);

A negative or zero value will result in an AL_INVALID_VALUE error, and the command is ignored. The default value is 343.3 (appropriate for velocity units of meters and air as the propagation medium). The current setting can be queried using alGetFloat{v} and AL_SPEED_OF_SOUND.

Distance and velocity units are completely independent of one another (so you could use different units for each if desired). If an OpenAL application doesn't want to use Doppler effects, then leaving all velocities at zero will achieve that result.

Error Handling

The error state of OpenAL can be retrieved at any time using alGetError. alGetError clears the error state of OpenAL when it is called, so it is common for an OpenAL application to call alGetError at the beginning of a critical operation to clear the error state, perform the critical operation, and then use alGetError again to test whether or not an error occurred.

Error Codes:

Error Code Description
AL_NO_ERROR there is not currently an error
AL_INVALID_NAME a bad name (ID) was passed to an OpenAL function
AL_INVALID_ENUM an invalid enum value was passed to an OpenAL function
AL_INVALID_VALUE an invalid value was passed to an OpenAL function
AL_INVALID_OPERATION the requested operation is not valid
AL_OUT_OF_MEMORY the requested operation resulted in OpenAL running out of memory

Example:

alGetError();  // Clear Error Code

// Generate Buffers
alGenBuffers(NUM_BUFFERS, g_Buffers);
if ((error = alGetError()) != AL_NO_ERROR)
{
    DisplayALError("alGenBuffers :", error);
    exit(-1);
}

Extensions

OpenAL has an extension mechanism that can be used by OpenAL vendors to add new features to the API. Creative Labs have added a number of extensions including EAX, X-RAM, Multi Channel Buffer playback, and most recently an Effect Extension (EFX). To determine if an extension is available the application can use either alIsExtensionPresent or alcIsExtensionPresent depending on the type of extension. The Appendices contain more details about some of Creative’s extensions to OpenAL.

Buffer Functions

Properties

Property Data Type Description
AL_FREQUENCY i, iv Frequency of buffer in Hz
AL_BITS i, iv Bit depth of buffer
AL_CHANNELS i, iv Number of channels in buffer. > 1 is valid, but buffer won’t be positioned when played
AL_SIZE i, iv Size of buffer in bytes
AL_DATA i, iv Original location where data was copied from generally useless, as was probably freed after buffer creation

Functions

alGenBuffers

Description

This function generates one or more buffers, which contain audio data (see alBufferData). References to buffers are ALuint values, which are used wherever a buffer reference is needed (in calls such as alDeleteBuffers, alSourcei, alSourceQueueBuffers, and alSourceUnqueueBuffers).

void alGenBuffers(
    ALsizei n,
    ALuint *buffers
);
Parameters
  • n - The number of buffers to be generated
  • buffers - Pointer to an array of ALuint values which will store the names of the new buffers
Possible Error States
State Description
AL_INVALID_VALUE The buffer array isn't large enough to hold the number of buffers requested.
AL_OUT_OF_MEMORY There is not enough memory available to generate all the buffers requested.
Version Requirements

OpenAL 1.0 or higher

Remarks

If the requested number of buffers cannot be created, an error will be generated which can be detected with alGetError. If an error occurs, no buffers will be generated. If n equals zero, alGenBuffers does nothing and does not return an error.

See Also

alDeleteBuffers, alIsBuffer

alDeleteBuffers

Description

This function deletes one or more buffers, freeing the resources used by the buffer. Buffers which are attached to a source can not be deleted. See alSourcei and alSourceUnqueueBuffers for information on how to detach a buffer from a source.

void alDeleteBuffers(
    ALsizei n,
    ALuint *buffers
);
Parameters
  • n - The number of buffers to be deleted
  • buffers - Pointer to an array of buffer names identifying the buffers to be deleted
Possible Error States
State Description
AL_INVALID_OPERATION The buffer is still in use and can not be deleted.
AL_INVALID_NAME A buffer name is invalid.
AL_INVALID_VALUE The requested number of buffers can not be deleted.
Version Requirements

OpenAL 1.0 or higher

Remarks

If the requested number of buffers cannot be deleted, an error will be generated which can be detected with alGetError. If an error occurs, no buffers will be deleted. If n equals zero, alDeleteBuffers does nothing and will not return an error.

See Also

alGenBuffers, alIsBuffer

alIsBuffer

Description

This function tests if a buffer name is valid, returning AL_TRUE if valid, AL_FALSE if not.

ALboolean alIsBuffer(
    ALuint buffer
);
Parameters
  • buffer - A buffer name to be tested for validity
Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

The NULL buffer is always valid (see alSourcei for information on how the NULL buffer is used).

See Also

alGenBuffers, alDeleteBuffers

alBufferData

Description

This function fills a buffer with audio data. All the pre-defined formats are PCM data, but this function may be used by extensions to load other data types as well.

void alBufferData(
    ALuint buffer,
    ALenum format,
    const ALvoid *data,
    ALsizei size,
    ALsizei freq
);
Parameters
  • buffer - Buffer name to be filled with data
  • format - Format type from among the following:
    • AL_FORMAT_MONO8
    • AL_FORMAT_MONO16
    • AL_FORMAT_STEREO8
    • AL_FORMAT_STEREO16
  • data - Pointer to the audio data
  • size - The size of the data in bytes
  • freq - The frequency of the audio data
Possible Error States
State Description
AL_OUT_OF_MEMORY There is not enough memory available to create this buffer.
AL_INVALID_VALUE The size parameter is not valid for the format specified, the buffer is in use, or the data is a NULL pointer.
AL_INVALID_ENUM The specified format does not exist.
Version Requirements

OpenAL 1.0 or higher

Remarks

8-bit PCM data is expressed as an unsigned value over the range 0 to 255, 128 being an audio output level of zero. 16-bit PCM data is expressed as a signed value over the range -32768 to 32767, 0 being an audio output level of zero. Stereo data is expressed in interleaved format, left channel first. Buffers containing more than one channel of data will be played without 3D spatialization.

alBufferf

Description

This function sets a floating point property of a buffer.

void alBufferf(
    ALuint buffer,
    ALenum param,
    ALfloat value
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • value - The ALfloat value to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBuffer3f, alBufferfv, alGetBufferf, alGetBuffer3f, alGetBufferfv

alBuffer3f

Description

This function sets a floating point property of a buffer.

void alBuffer3f(
    ALuint buffer,
    ALenum param,
    ALfloat v1,
    ALfloat v2,
    ALfloat v3
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • v1, v2, v3 - The ALfloat values to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferf, alBufferfv, alGetBufferf, alGetBuffer3f, alGetBufferfv

alBufferfv

Description

This function sets a floating point property of a buffer.

void alBuffer3f(
    ALuint buffer,
    ALenum param,
    ALfloat* value
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • values - A pointer to the ALfloat values to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferf, alBuffer3f, alGetBufferf, alGetBuffer3f, alGetBufferfv

alBufferi

Description

This function sets an integer property of a buffer.

void alBufferi(
    ALuint buffer,
    ALenum param,
    ALint value
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • values - The ALint value to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBuffer3i, alBufferiv, alGetBufferi, alGetBuffer3i, alGetBufferiv

alBuffer3i

Description

This function sets an integer property of a buffer.

void alBuffer3i(
    ALuint buffer,
    ALenum param,
    ALint v1,
    ALint v2,
    ALint v3,
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • v1, v2, v3 - The ALint values to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferi, alBufferiv, alGetBufferi, alGetBuffer3i, alGetBufferiv

alBufferiv

Description

This function sets an integer property of a buffer.

void alBufferiv(
    ALuint buffer,
    ALenum param,
    ALint* values
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be set
  • values - A pointer to the ALint values to be set
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferi, alBuffer3i, alGetBufferi, alGetBuffer3i, alGetBufferiv

alGetBufferf

Description

This function retrieves a floating point property of a buffer.

void alGetBufferf(
    ALuint buffer,
    ALenum pname,
    ALfloat* value
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved
  • value - A pointer to an ALfloat to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferf, alBuffer3f, alBufferfv, alGetBuffer3f, alGetBufferfv

alGetBuffer3f

Description

This function retrieves a floating point property of a buffer.

void alGetBuffer3f(
    ALuint buffer,
    ALenum pname,
    ALfloat* v1,
	ALfloat* v2,
	ALfloat* v3
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved
  • v1, v2, v3 - Pointers to ALfloat values to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferf, alBuffer3f, alBufferfv, alGetBufferf, alGetBufferfv

alGetBufferfv

Description

This function retrieves a floating point property of a buffer.

void alGetBufferfv(
    ALuint buffer,
    ALenum pname,
    ALfloat* values
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved
  • values - Pointer to an ALfloat vector to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be affected by this call, but this function may be used by OpenAL extensions.

See Also

alBufferf, alBuffer3f, alBufferfv, alGetBufferf, alGetBuffer3f

alGetBufferi

Description

This function retrieves an integer property of a buffer.

void alGetBufferi(
    ALuint buffer,
    ALenum pname,
    ALint* value
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved:
    • AL_FREQUENCY
    • AL_BITS
    • AL_CHANNELS
    • AL_SIZE
    • AL_DATA
  • value - Pointer to an ALint to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alBufferi, alBuffer3i, alBufferiv, alGetBuffer3i, alGetBufferiv

alGetBuffer3i

Description

This function retrieves an integer property of a buffer.

void alGetBuffer3i(
    ALuint buffer,
    ALenum pname,
    ALint* v1,
	ALint* v2,
	ALint* v3
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved
  • v1, v2, v3 - Pointer to ALint values to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.1 or higher

Remarks

There are no relevant buffer properties defined in OpenAL 1.1 which can be retrieved by this call, but this function may be used by OpenAL extensions.

See Also

alBufferi, alBuffer3i, alBufferiv, alGetBufferi, alGetBufferiv

alGetBufferiv

Description

This function retrieves an integer property of a buffer.

void alGetBufferiv(
    ALuint buffer,
    ALenum pname,
    ALint* values
);
Parameters
  • buffer - Buffer name whose attribute is being retrieved
  • param - The name of the attribute to be retrieved:
    • AL_FREQUENCY
    • AL_BITS
    • AL_CHANNELS
    • AL_SIZE
    • AL_DATA
  • values - Pointer to an ALint vector to hold the retrieved data
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified buffer doesn't have parameters (the NULL buffer), or doesn't exist.
AL_INVALID_VALUE The specified value pointer is not valid.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alBufferi, alBuffer3i, alBufferiv, alGetBufferi, alGetBuffer3i

Source Functions

Properties

Property Data Type Description
AL_PITCH f, fv Pitch multiplier. Always positive
AL_GAIN f, fv Source gain. Value should be positive
AL_MAX_DISTANCE f, fv, i, iv Used with the Inverse Clamped Distance Model to set the distance where there will no longer be any attenuation of the source
AL_ROLLOFF_FACTOR f, fv, i, iv The rolloff rate for the source. Default is 1.0
AL_REFERENCE_DISTANCE f, fv, i, iv The distance under which the volume for the source would normally drop by half (before being influenced by rolloff factor or AL_MAX_DISTANCE)
AL_MIN_GAIN f, fv The minimum gain for this source
AL_MAX_GAIN f, fv The maximum gain for this source
AL_CONE_OUTER_GAIN f, fv The gain when outside the oriented cone
AL_CONE_INNER_ANGLE f, fv, i, iv The gain when inside the oriented cone
AL_CONE_OUTER_ANGLE f, fv, i, iv Outer angle of the sound cone, in degrees. Default is 360
AL_POSITION fv, 3f X, Y, Z position
AL_VELOCITY fv, 3f Velocity vector
AL_DIRECTION fv, 3f, iv, 3i Direction vector
AL_SOURCE_RELATIVE i, iv Determines if the positions are relative to the listener. Default is AL_FALSE
AL_SOURCE_TYPE i, iv The source type: AL_UNDETERMINED, AL_STATIC or AL_STREAMING
AL_LOOPING i, iv Turns looping on (AL_TRUE) or off (AL_FALSE)
AL_BUFFER i, iv The ID of the attached buffer
AL_SOURCE_STATE i, iv The state of the source: AL_STOPPED, AL_PLAYING, ...
AL_BUFFERS_QUEUED i, iv The number of buffers queued on this source
AL_BUFFERS_PROCESSED i, iv The number of buffers in the queue that have been processed
AL_SEC_OFFSET f, fv, i, iv The playback position, expressed in seconds
AL_SAMPLE_OFFSET f, fv, i, iv The playback position, expressed in samples
AL_BYTE_OFFSET f, fv, i, iv The playback position, expressed in bytes

Functions

alGenSources

Description

This function generates one or more sources. References to sources are ALuint values, which are used wherever a source reference is needed (in calls such as alDeleteSources and alSourcei).

void alGenSources(
    ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to be generated
  • sources - Pointer to an array of ALuint vlaues which will store the names of the new sources
Possible Error States
State Description
AL_OUT_OF_MEMORY There is not enough memory to generate all the requested sources.
AL_INVALID_VALUE There are not enough non-memory resources to create all the requested sources, or the array pointer is not valid.
AL_INVALID_OPERATION There is no context to create sources in.
Version Requirements

OpenAL 1.0 or higher

Remarks

If the requested number of sources cannot be created, an error will be generated which can be detected with alGetError. If an error occurs, no sources will be generated. If n equals zero, alGenSources does nothing and does not return an error.

See Also

alDeleteSources, alIsSource

alDeleteSources

Description

This function deletes one or more sources.

void alDeleteSources(
    ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to be deleted
  • sources - Pointer to an array of source names identifying the sources to be deleted
Possible Error States
State Description
AL_INVALID_NAME At least one specified source is not valid, or an attempt is being made to delete more sources than exist.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

If the requested number of sources cannot be deleted, an error will be generated which can be detected with alGetError. If an error occurs, no sources will be deleted. If n equals zero, alDeleteSources does nothing and will not return an error.

A playing source can be deleted – the source will be stopped and then deleted.

See Also

alGenSources, alIsSource

alIsSource

Description

This function tests if a source name is valid, returning AL_TRUE if valid and AL_FALSE if not.

boolean alIsSource(
    ALuint source
);
Parameters
  • source - A source name to be tested for validity
Possible Error States
State Description
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGenSources, alDeleteSources

alSourcei

Description

This function sets an integer property of a source.

void alSourcef(
    ALuint source,
    ALenum param,
    ALfloat value
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_PITCH
    • AL_GAIN
    • AL_MIN_GAIN
    • AL_MAX_GAIN
    • AL_MAX_DISTANCE
    • AL_ROLLOFF_FACTOR
    • AL_CONE_OUTER_GAIN
    • AL_CONE_INNER_ANGLE
    • AL_CONE_OUTER_ANGLE
    • AL_REFERENCE_DISTANCE
  • value - The value to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alSource3f, alSourcefv, alGetSourcef, alGetSource3f, alGetSourcefv

alSource3f

Description

This function sets a source property requiring three floating point values.

void alSource3f(
    ALuint source,
    ALenum param,
    ALfloat v1,
	ALfloat v2,
	ALfloat v3
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • v1, v2, v3 - The three ALfloat values to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

This function is an alternative to alSourcefv.

See Also

alSourcef, alSourcefv, alGetSourcef, alGetSource3f, alGetSourcefv

alSourcefv

Description

This function sets a floating point-vector property of a source.

void alSourcefv(
    ALuint source,
    ALenum param,
    ALfloat* values
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • values - A pointer to the vector to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

This function is an alternative to alSource3f.

See Also

alSourcef, alSource3f, alGetSourcef, alGetSource3f, alGetSourcefv

alSourcei

Description

This function sets an integer property of a source.

void alSourcei(
    ALuint source,
    ALenum param,
    ALint value
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_SOURCE_RELATIVE
    • AL_CONE_INNER_ANGLE
    • AL_CONE_OUTER_ANGLE
    • AL_LOOPING
    • AL_BUFFER
    • AL_SOURCE_STATE
  • value - The value to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The buffer name zero is reserved as a “NULL Buffer" and is accepted by alSourcei(…, AL_BUFFER, …) as a valid buffer of zero length. The NULL Buffer is extremely useful for detaching buffers from a source which were attached using this call or with alSourceQueueBuffers.

See Also

alSource3i, alSourceiv, alGetSourcei, alGetSource3i, alGetSourceiv

alSource3i

Description

This function sets a source property requiring three integer values.

void alSource3i(
    ALuint source,
    ALenum param,
    ALint v1,
	ALint v2,
	ALint v3
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • v1, v2, v3 - The three ALint values to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alSourcei, alSourceiv, alGetSourcei, alGetSource3i, alGetSourceiv

alSourceiv

Description

This function sets an integer-vector property of a source.

void alSourceiv(
    ALuint source,
    ALenum param,
    ALint* values
);
Parameters
  • source - Source name whose attribute is being set
  • param - The name of the attribute to set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • values - A pointer to the vector to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is out of range.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alSourcei, alSource3i, alGetSourcei, alGetSource3i, alGetSourceiv

alGetSourcei

Description

This function sets an integer property of a source.

void alGetSourcei(
    ALuint source,
    ALenum param,
    ALint* value
);
Parameters
  • source - Source name whose attribute is being retrieved
  • param - The name of the attribute to retrieve:
    • AL_SOURCE_RELATIVE
    • AL_BUFFER
    • AL_SOURCE_STATE
    • AL_BUFFERS_QUEUED
    • AL_BUFFERS_PROCESSED
  • values - A pointer to the integer value being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alSourcei, alSource3i, alSourceiv, alGetSource3i, alGetSourceiv

alGetSource3i

Description

This function retrieves three integer values representing a property of a source.

void alGetSource3i(
    ALuint source,
    ALenum param,
    ALint* v1,
	ALint* v2,
	ALint* v3
);
Parameters
  • source - Source name whose attribute is being retrieved
  • param - The name of the attribute to retrieve:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • values - Pointer to the values to retrieve
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alSourcei, alSource3i, alSourceiv, alGetSourcei, alGetSourceiv

alGetSourceiv

Description

This function retrieves an integer property of a source.

void alGetSourceiv(
    ALuint source,
    ALenum param,
    ALint* values
);
Parameters
  • source - Source name whose attribute is being retrieved
  • param - The name of the attribute to retrieve:
    • AL_POSITION
    • AL_VELOCITY
    • AL_DIRECTION
  • values - Pointer to the vector to retrieve
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alSourcei, alSource3i, alSourceiv, alGetSourcei, alGetSource3i

alSourcePlay

Description

This function plays a source.

void alSourcePlay(
    ALuint source
);
Parameters
  • source - The name of the source to be played
Possible Error States
State Description
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The playing source will have its state changed to AL_PLAYING. When called on a source which is already playing, the source will restart at the beginning. When the attached buffer(s) are done playing, the source will progress to the AL_STOPPED state.

See Also

alSourcePlayv, alSourcePause, alSourcePausev, alSourceRewind, alSourceRewindv, alSourceStop, alsourcestopv

alSourcePlayv

Description

This function plays a set of sources.

void alSourcePlayv(
	ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to be played
  • source - A pointer to an array of sources to be played
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The playing sources will have their state changed to AL_PLAYING. When called on a source which is already playing, the source will restart at the beginning. When the attached buffer(s) are done playing, the source will progress to the AL_STOPPED state.

See Also

alSourcePlay, alSourcePause, alSourcePausev, alSourceRewind, alSourceRewindv, alSourceStop, alsourcestopv

alSourcePause

Description

This function pauses a source.

void alSourcePause(
    ALuint source
);
Parameters
  • source - The name of the source to be paused
Possible Error States
State Description
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The paused source will have its state changed to AL_PAUSED.

See Also

alSourcePlay, alSourcePlayv, alSourcePausev, alSourceRewind, alSourceRewindv, alSourceStop, alsourcestopv

alSourcePausev

Description

This function pauses a set of sources.

void alSourcePausev(
	ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to be paused
  • source - A pointer to an array of sources to be paused
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The paused sources will have their state changed to AL_PAUSED.

See Also

alSourcePlay, alSourcePlayv, alSourcePause, alSourceRewind, alSourceRewindv, alSourceStop, alsourcestopv

alSourceStop

Description

This function stops a source.

void alSourceStop(
    ALuint source
);
Parameters
  • source - The name of the source to be stopped
Possible Error States
State Description
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The paused source will have its state changed to AL_STOPPED.

See Also

alSourcePlay, alSourcePlayv, alSourcePause, alSourcePausev, alSourceRewind, alSourceRewindv, alsourcestopv

alSourceStopv

Description

This function stops a set of sources.

void alSourceStopv(
	ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to stop
  • source - A pointer to an array of sources to be stopped
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The paused sources will have their state changed to AL_STOPPED.

See Also

alSourcePlay, alSourcePlayv, alSourcePause, alSourceRewind, alSourceRewindv, alSourceStop, alsourcestop

alSourceRewind

Description

This function stops the source and sets its state to AL_INITIAL.

void alSourceRewind(
    ALuint source
);
Parameters
  • source - The name of the source to be rewound
Possible Error States
State Description
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alSourcePlay, alSourcePlayv, alSourcePause, alSourcePausev, alSourceRewindv, alsourcestop, alsourcestopv

alSourceRewindv

Description

his function stops a set of sources and sets all their states to AL_INITIAL.

void alSourceRewindv(
	ALsizei n,
    ALuint *sources
);
Parameters
  • n - The number of sources to be rewound
  • source - A pointer to an array of sources to be rewound
Possible Error States
State Description
AL_INVALID_VALUE The value pointer given is not valid.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alSourcePlay, alSourcePlayv, alSourcePause, alSourcePausev, alSourceRewind, alSourceStop, alsourcestop

alSourceQueueBuffers

Description

This function queues a set of buffers on a source. All buffers attached to a source will be played in sequence, and the number of processed buffers can be detected using an alSourcei call to retrieve AL_BUFFERS_PROCESSED.

void alSourceQueueBuffers(
    ALuint source,
	ALsizei n,
	ALuint* buffers
);
Parameters
  • source - The name of the source to queue buffers onto
  • n - The number of buffers to be queued
  • buffers - A pointer to an array of buffer names to be queued
Possible Error States
State Description
AL_INVALID_NAME At least one specified buffer name is not valid, or the specified source name is not valid.
AL_INVALID_OPERATION There is no current context, an attempt was made to add a new buffer which is not the same format as the buffers already in the queue, or the source already has a static buffer attached.
Version Requirements

OpenAL 1.0 or higher

Remarks

When first created, a source will be of type AL_UNDETERMINED. A successful alSourceQueueBuffers call will change the source type to AL_STREAMING.

See Also

alSourceUnqueueBuffers

alSourceUnqueueBuffers

Description

This function unqueues a set of buffers attached to a source. The number of processed buffers can be detected using an alSourcei call to retrieve AL_BUFFERS_PROCESSED, which is the maximum number of buffers that can be unqueued using this call.

void alSourceUnqueueBuffers(
    ALuint source,
	ALsizei n,
	ALuint* buffers
);
Parameters
  • source - The name of the source to unqueue buffers from
  • n - The number of buffers to be unqueued
  • buffers - A pointer to an array of buffer names that were removed
Possible Error States
State Description
AL_INVALID_VALUE At least one buffer can not be unqueued because it has not been processed yet.
AL_INVALID_NAME The specified source name is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The unqueue operation will only take place if all n buffers can be removed from the queue.

See Also

alSourceQueueBuffers

Listener Functions

Properties

Property Data Type Description
AL_GAIN f, fv Master gain. Value should be positive
AL_POSITION fv, 3f, iv, 3i X, Y, Z position
AL_VELOCITY fv, 3f, iv, 3i Velocity vector
AL_ORIENTATION fv, fv Orientation expressed as "at" and "up" vectors

Functions

alListenerf

Description

This function sets a floating point property for the listener.

void alListenerf(
    ALenum param,
	ALfloat value
);
Parameters
  • param - The name of the attribute to be set:
    • AL_GAIN
  • value - The ALfloat value to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListener3f, alListenerfv, alGetListenerf, alGetListener3f, alGetListenerfv

alListener3f

Description

This function sets a floating point property for the listener.

void alListener3f(
    ALenum param,
	ALfloat v1,
	ALfloat v2,
	ALfloat v3
);
Parameters
  • param - The name of the attribute to be set:
    • AL_POSITION
    • AL_VELOCITY
  • v1, v2, v3 - The value to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListenerf, alListenerfv, alGetListenerf, alGetListener3f, alGetListenerfv

alListenerfv

Description

This function sets a floating point-vector property for the listener.

void alListenerfv(
    ALenum param,
	ALfloat* values
);
Parameters
  • param - The name of the attribute to be set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_ORIENTATION
  • values - Pointer to floating point-vector values
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListenerf, alListener3f, alGetListenerf, alGetListener3f, alGetListenerfv

alListeneri

Description

This function sets an integer property for the listener.

void alListeneri(
    ALenum param,
	ALint value
);
Parameters
  • param - The name of the attribute to be set
  • value - The integer value to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

There are no integer listener attributes defined for OpenAL 1.1, but this function may be used by an extension.

See Also

alListener3i, alListeneriv, alGetListeneri, alGetListener3i, alGetListeneriv

alListener3i

Description

This function sets an integer property for the listener.

void alListener3i(
    ALenum param,
	ALint v1,
	ALint v2,
	ALint v3
);
Parameters
  • param - The name of the attribute to be set:
    • AL_POSITION
    • AL_VELOCITY
  • v1, v2, v3 - The integer values to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alListeneri, alListeneriv, alGetListeneri, alGetListener3i, alGetListeneriv

alListeneriv

Description

This function sets an integer property for the listener.

void alListeneriv(
    ALenum param,
	ALint* values
);
Parameters
  • param - The name of the attribute to be set:
    • AL_POSITION
    • AL_VELOCITY
    • AL_ORIENTATION
  • values - Pointer to the integer values to set the attribute to
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alListeneri, alListener3i, alGetListeneri, alGetListener3i, alGetListeneriv

alGetListenerf

Description

This function retrieves a floating point property of the listener.

void alGetListenerf(
    ALenum param,
	ALfloat* value
);
Parameters
  • param - The name of the attribute to be retrieved:
    • AL_GAIN
  • values - Pointer to the floating-point value being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListenerf, alListener3f, alListenerfv, alGetListener3f, alGetListenerfv

alGetListener3f

Description

This function retrieves a set of three floating point values from a property of the listener.

void alGetListener3f(
    ALenum param,
	ALfloat* v1,
	ALfloat* v2,
	ALfloat* v3
);
Parameters
  • param - The name of the attribute to be retrieved:
    • AL_POSITION
    • AL_VELOCITY
  • v1, v2, v3 - Pointers to the three floating point being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListenerf, alListener3f, alListenerfv, alGetListenerf, alGetListenerfv

alGetListenerfv

Description

This function retrieves a floating point-vector property of the listener.

void alGetListenerfv(
    ALenum param,
	ALfloat* values
);
Parameters
  • param - The name of the attribute to be retrieved:
    • AL_POSITION
    • AL_VELOCITY
    • AL_ORIENTATION
  • values - Pointers to the three floating point being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alListenerf, alListener3f, alListenerfv, alGetListenerf, alGetListener3f

alGetListeneri

Description

This function retrieves an integer property of the listener.

void alGetListeneri(
    ALenum param,
	ALint* value
);
Parameters
  • param - The name of the attribute to be retrieved:
  • values - Pointer to the integer value being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

There are no integer listener attributes defined for OpenAL 1.1, but this function may be used by an extension.

See Also

alListeneri, alListener3i, alListeneriv, alGetListener3i, alGetListeneriv

alGetListener3i

Description

This function retrieves an integer property of the listener.

void alGetListener3i(
    ALenum param,
	ALint* v1,
	ALint* v2,
	ALint* v3
);
Parameters
  • param - The name of the attribute to be retrieved:
    • AL_POSITION
    • AL_VELOCITY
  • v1, v2, v3 - Pointers to the integer values being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alListeneri, alListener3i, alListeneriv, alGetListeneri, alGetListeneriv

alGetListeneriv

Description

This function retrieves an integer property of the listener.

void alGetListeneriv(
    ALenum param,
	ALint* values
);
Parameters
  • param - The name of the attribute to be retrieved:
    • AL_POSITION
    • AL_VELOCITY
    • AL_ORIENTATION
  • values - Pointers to the integer values being retrieved
Possible Error States
State Description
AL_INVALID_VALUE The value given is not valid.
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alListeneri, alListener3i, alListeneriv, alGetListeneri, alGetListener3i

State Functions

Properties

Property Data Type Description
AL_DOPPLER_FACTOR f Global Doppler factor
AL_SPEED_OF_SOUND f Speed of sound in units per second
AL_DISTANCE_MODEL f Distance model enumeration value

Functions

alEnable

Description

This function enables a feature of the OpenAL driver.

void alEnable(
    ALenum capability
);
Parameters
  • capability - the name of a capability to enable
Possible Error States
State Description
AL_INVALID_ENUM The specified capability is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

There are no capabilities defined in OpenAL 1.1 to be used with this function, but it may be used by an extension.

See Also

alDisable, alIsEnabled

alDisable

Description

This function disables a feature of the OpenAL driver.

void alDisable(
    ALenum capability
);
Parameters
  • capability - the name of a capability to distable
Possible Error States
State Description
AL_INVALID_ENUM The specified capability is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

There are no capabilities defined in OpenAL 1.1 to be used with this function, but it may be used by an extension.

See Also

alEnable, alIsEnabled

alIsEnabled

Description

This function returns a boolean indicating if a specific feature is enabled in the OpenAL driver.

ALboolean alIsEnabled(
    ALenum capability
);
Parameters
  • capability - the name of a capability to check
Possible Error States
State Description
AL_INVALID_ENUM The specified capability is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns AL_TRUE if the capability is enabled, AL_FALSE if the capability is disabled. There are no capabilities defined in OpenAL 1.1 to be used with this function, but it may be used by an extension.

See Also

alEnable, alDisable

alGetBoolean

Description

This function returns a boolean OpenAL state.

ALboolean alGetBoolean(
    ALenum param
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The boolean state described by param will be returned.

See Also

alGetBooleanv, alGetDouble, alGetDoublev, alGetFloat, alGetFloatv, alGetInteger, alGetIntegerv

alGetDouble

Description

This function returns a double precision floating point OpenAL state.

ALdouble alGetDouble(
    ALenum param
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The double value described by param will be returned.

See Also

alGetBoolean, alGetBooleanv, alGetDoublev, alGetFloat, alGetFloatv, alGetInteger, alGetIntegerv

alGetFloat

Description

This function returns a floating point OpenAL state.

ALfloat alGetFloat(
    ALenum param
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The floating point state described by param will be returned.

See Also

alGetBoolean, alGetBooleanv, alGetDouble, alGetDoublev, alGetFloatv, alGetInteger, alGetIntegerv

alGetInteger

Description

This function returns an integer OpenAL state.

ALint alGetInteger(
    ALenum param
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The integer state described by param will be returned.

See Also

alGetBoolean, alGetBooleanv, alGetDouble, alGetDoublev, alGetFloat, alGetFloatv, alGetIntegerv

alGetBooleanv

Description

This function returns an integer OpenAL state.

void alGetBooleanv(
    ALenum param,
	ALboolean* data
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
  • data - A pointer to the location where the state will be stored
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_VALUE The specified data pointer is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGetBoolean, alGetDouble, alGetDoublev, alGetFloat, alGetFloatv, alGetInteger, alGetIntegerv

alGetDoublev

Description

This function retrieves a double precision floating point OpenAL state.

void alGetDoublev(
    ALenum param,
	ALdouble* data
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
  • data - A pointer to the location where the state will be stored
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_VALUE The specified data pointer is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGetBoolean, alGetBooleanv, alGetDouble, alGetFloat, alGetFloatv, alGetInteger, alGetIntegerv

alGetFloatv

Description

This function retrieves a floating point OpenAL state.

void alGetFloatv(
    ALenum param,
	ALfloat* data
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
  • data - A pointer to the location where the state will be stored
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_VALUE The specified data pointer is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGetBoolean, alGetBooleanv, alGetDouble, alGetDoublev, alGetFloat, alGetInteger, alGetIntegerv

alGetIntegerv

Description

This function retrieves an integer OpenAL state.

void alGetIntegerv(
    ALenum param,
	ALint* data
);
Parameters
  • param - the state to be queried:
    • AL_DOPPLER_FACTOR
    • AL_SPEED_OF_SOUND
    • AL_DISTANCE_MODEL
  • data - A pointer to the location where the state will be stored
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
AL_INVALID_VALUE The specified data pointer is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGetBoolean, alGetBooleanv, alGetDouble, alGetDoublev, alGetFloat, alGetFloatv, alGetInteger

alGetString

Description

This function retrieves an OpenAL string property.

const ALchar* alGetString(
    ALenum param
);
Parameters
  • param - the state to be queried:
    • AL_VENDOR
    • AL_VERSION
    • AL_RENDERER
    • AL_EXTENSIONS
Possible Error States
State Description
AL_INVALID_ENUM The specified parameter is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns a pointer to a null-terminated string.

alDistanceModel

Description

This function selects the OpenAL distance model – AL_INVERSE_DISTANCE, AL_INVERSE_DISTANCE_CLAMPED, AL_LINEAR_DISTANCE, AL_LINEAR_DISTANCE_CLAMPED, AL_EXPONENT_DISTANCE, AL_EXPONENT_DISTANCE_CLAMPED, or AL_NONE.

The AL_INVERSE_DISTANCE model works according to the following formula:

gain = AL_REFERENCE_DISTANCE / (AL_REFERENCE_DISTANCE
     + AL_ROLLOFF_FACTOR * (distance - AL_REFERENCE_DISTANCE));

The AL_INVERSE_DISTANCE_CLAMPED model works according to the following formula:

distance = max(distance, AL_REFERENCE_DISTANCE);
distance = min(distance, AL_MAX_DISTANCE);
gain = AL_REFERENCE_DISTANCE / (AL_REFERENCE_DISTANCE
     + AL_ROLLOFF_FACTOR * (distance - AL_REFERENCE_DISTANCE));

Here is a graph showing the inverse distance curve: Inverse Distance Curve

The AL_LINEAR_DISTANCE model works according to the following formula:

distance = min(distance, AL_MAX_DISTANCE);	// Avoid negative gain
gain = (1 - AL_ROLLOFF_FACTOR * (distance -
            AL_REFERENCE_DISTANCE) /
			(AL_MAX_DISTANCE - AL_REFERENCE_DISTANCE));

The AL_LINEAR_DISTANCE_CLAMPED model works according to the following formula:

distance = max(distance, AL_REFERENCE_DISTANCE);
distance = min(distance, AL_MAX_DISTANCE);
gain = (1 - AL_ROLLOFF_FACTOR * (distance -
            AL_REFERENCE_DISTANCE) /
           (AL_MAX_DISTANCE - AL_REFERENCE_DISTANCE));

Here is a graph showing the linear distance curve: Inverse Distance Curve

The AL_EXPONENT_DISTANCE model works according to the following forumula:

gain = pow(distance / AL_REFERENCE_DISTANCE, -AL_ROLLOFF_FACTOR);

The AL_EXPONENT_DISTANCE_CLAMPED model works according to the following forumla:

distance = max(distance, AL_REFERENCE_DISTANCE);
distance = min(distance, AL_MAX_DISTANCE);
gain = pow(distance / AL_REFERENCE_DISTANCE, -AL_ROLLOFF_FACTOR);

Here is a graph showing the exponential distance curve: Inverse Distance Curve

The AL_NONE distance model works according to the following formula:

gain = 1;
void alDistanceModel(
    ALenum value
);
Parameters
  • value - The distance model to be set:
    • AL_INVERSE_DISTANCE
    • AL_INVERSE_DISTANCE_CLAMPED
    • AL_LINEAR_DISTANCE
    • AL_LINEAR_DISTANCE_CLAMPED
    • AL_EXPONENT_DISTANCE
    • AL_EXPONENT_DISTANCE_CLAMPED
    • AL_NONE
Possible Error States
State Description
AL_INVALID_VALUE The specified distance model is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The default distance model in OpenAL is AL_INVERSE_DISTANCE_CLAMPED.

alDopplerFactor

Description

This function selects the OpenAL Doppler factor value.

void alDopplerFactor(
    ALfloat value
);
Parameters
  • value - The Doppler scale value to set
Possible Error States
State Description
AL_INVALID_VALUE The specified distance model is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.0 or higher

Remarks

The default Doppler factor value is 1.0.

alSpeedOfSound

Description

This function selects the speed of sound for use in Doppler calculations.

void alSpeedOfSound(
    ALfloat value
);
Parameters
  • value - The speed of sound value to set
Possible Error States
State Description
AL_INVALID_VALUE The specified distance model is not valid.
AL_INVALID_OPERATION There is no current context.
Version Requirements

OpenAL 1.1 or higher

Remarks

The default speed of sound value is 343.3.

Error Functions

Error Codes

Error Code Description
AL_NO_ERROR There is not currently an error
AL_INVALID_NAME A bad name (ID) was passed to an OpenAL function
AL_INVALID_ENUM An invalid enum value was passed to an OpenAL function
AL_INVALID_VALUE An invalid value was passed to an OpenAL function
AL_INVALID_OPERATION The requested operation is not valid
AL_OUT_OF_MEMORY The requested operation resulted in OpenAL running out of memory

Functions

alGetError

Description

This function returns the current error state and then clears the error state.

ALenum alGetError(ALvoid);
Parameters

None

Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

Returns an Alenum representing the error state. When an OpenAL error occurs, the error state is set and will not be changed until the error state is retrieved using alGetError. Whenever alGetError is called, the error state is cleared and the last state (the current state when the call was made) is returned. To isolate error detection to a specific portion of code, alGetError should be called before the isolated section to clear the current error state.

Extension Functions

Functions

alIsExtensionPresent

Description

This function tests if a specific extension is available for the OpenAL driver.

ALboolean alIsExtensionPresent(
    const ALchar *extname
);
Parameters
  • extname - A null-terminated string describing the desired extension
Possible Error States
State Description
AL_INVALID_VALUE The specified extension string is not a valid pointer.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns AL_TRUE if the extension is available, AL_FALSE if the extension is not available.

See Also

alGetProcAddress, alGetEnumValue

alGetProcAddress

Description

This function returns the address of an OpenAL extension function.

void* alGetProcAddress(
    const ALchar *fname
);
Parameters
  • fname - A null-terminated string containing the function name
Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

The return value is a pointer to the specified function. The return value will be NULL if the function is not found.

See Also

alIsExtensionPresent, alGetEnumValue

alGetEnumValue

Description

This function returns the enumeration value of an OpenAL enum described by a string.

ALenum alGetEnumValue(
    const ALchar *ename
);
Parameters
  • ename - A null-terminated string describing an OpenAL enum
Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

Returns the actual ALenum described by a string. Returns NULL if the string doesn’t describe a valid OpenAL enum.

See Also

alIsExtensionPresent, alGetProcAddress

Context Management Functions

Properties

Property Data Type Description
ALC_FREQUENCY i Output frequency
ALC_MONO_SOURCES i Requested number of mono sources
ALC_STEREO_SOURCES i Requested number of stereo sources
ALC_REFRESH i Update rate of context processing
ALC_SYNC i Flag indicating a synchronous context

Functions

alcCreateContext

Description

This function creates a context using a specified device.

ALCcontext* alcCreateContext(
    ALCdevice* device,
    ALCint* attrlist
);
Parameters
  • device - A pointer to a device
  • attrlist - A pointer to a set of attributes:
    • ALC_FREQUENCY
    • ALC_MONO_SOURCES
    • ALC_REFRESH
    • ALC_STEREO_SOURCES
    • ALC_SYNC
Possible Error States
State Description
ALC_INVALID_VALUE An additional context can not be created for this device.
ALC_INVALID_DEVICE The specified device is not a valid output device.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns a pointer to the new context (NULL on failure).

The attribute list can be NULL, or a zero terminated list of integer pairs composed of valid ALC attribute tokens and requested values.

See Also

alcDestroyContext, alcMakeContextCurrent

alcMakeContextCurrent

Description

This function makes a specified context the current context.

ALCboolean alcMakeContextCurrent(
    ALCcontext *context
);
Parameters
  • context - A pointer to the new context
Possible Error States
State Description
ALC_INVALID_CONTEXT The specified context is invalid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns ALC_TRUE on success, or ALC_FALSE on failure.

See Also

alcCreateContext, alcDestroyContext

alcProcessContext

Description

This function tells a context to begin processing.

void alcProcessContext(
    ALCcontext *context
);
Parameters
  • context - A pointer to the context
Possible Error States
State Description
ALC_INVALID_CONTEXT The specified context is invalid.
Version Requirements

OpenAL 1.0 or higher

Remarks

When a context is suspended, changes in OpenAL state will be accepted but will not be processed. alcSuspendContext can be used to suspend a context, and then all the OpenAL state changes can be applied at once, followed by a call to alcProcessContext to apply all the state changes immediately. In some cases, this procedure may be more efficient than application of properties in a non-suspended state. In some implementations, process and suspend calls are each a NOP.

See Also

alcSuspendContext

alcSuspendContext

Description

This function suspends processing on a specified context.

void alcSuspendContext(
    ALCcontext *context
);
Parameters
  • context - A pointer to the context to be suspended
Possible Error States
State Description
ALC_INVALID_CONTEXT The specified context is invalid.
Version Requirements

OpenAL 1.0 or higher

Remarks

When a context is suspended, changes in OpenAL state will be accepted but will not be processed. A typical use of alcSuspendContext would be to suspend a context, apply all the OpenAL state changes at once, and then call alcProcessContext to apply all the state changes at once. In some cases, this procedure may be more efficient than application of properties in a non-suspended state. In some implementations, process and suspend calls are each a NOP.

See Also

alcProcessContext

alcDestroyContext

Description

This function destroys a context.

void alcDestroyContext(
    ALCcontext *context
);
Parameters
  • context - A pointer to the context
Possible Error States
State Description
ALC_INVALID_CONTEXT The specified context is invalid.
Version Requirements

OpenAL 1.0 or higher

Remarks

A context which is not current can be destroyed at any time (all sources within that context will also be deleted). alcMakeContextCurrent should be used to make sure the context to be destroyed is not current (NULL is valid for alcMakeContextCurrent).

See Also

alcCreateContext, alcMakeContextCurrent

alcGetCurrentContext

Description

This function retrieves the current context.

ALCcontext* alcGetCurrentContext(ALCvoid);
Parameters

None

Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

Returns a pointer to the current context.

See Also

alcGetContextsDevice

alcGetContextsDevice

Description

This function retrieves a context's device pointer.

ALCdevice* alcGetContextsDevice(ALCcontext *context);
Parameters
  • context - A pointer to a context
Possible Error States
State Description
ALC_INVALID_CONTEXT The specified context is invalid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns a pointer to the specified context's device.

See Also

alcGetCurrentContext

Context Error Functions

Error Codes

Error Code Description
ALC_NO_ERROR There is not currently an error
ALC_INVALID_DEVICE A bad device was passed to an OpenAL function
ALC_INVALID_CONTEXT A bad context was passed to an OpenAL function
ALC_INVALID_ENUM An unknown enum value was passed to an OpenAL function
ALC_INVALID_VALUE An invalid value was passed to an OpenAL function
ALC_OUT_OF_MEMORY The requested operation resulted in OpenAL running out of memory

Functions

alcGetError

Description

This function retrieves the current context error state.

ALCenum alcGetError(ALCdevice *device);
Parameters
  • device - A pointer to the device to retrieve the error state from
Possible Error States

None

Version Requirements

OpenAL 1.0 or higher

Remarks

None

Context Device Functions

Functions

alcOpenDevice

Description

This function opens a device by name.

ALCdevice* alcOpenDevice(
    const ALCchar* devicename
);
Parameters
  • devicename - A null-terminated string describing a device
Possible Error States

The return value will be NULL if there is an error.

Version Requirements

OpenAL 1.0 or higher

Remarks

Returns a pointer to the opened device. Will return NULL if a device can not be opened.

See Also

alcCloseDevice

alcCloseDevice

Description

This function closes an opened device.

ALCboolean alcCloseDevice(
    ALCdevice* device
);
Parameters
  • device - A pointer to an opened device
Possible Error States
State Description
ALC_INVALID_DEVICE The specified device name doesn't exist.
Version Requirements

OpenAL 1.0 or higher

Remarks

ALC_TRUE will be returned on success or ALC_FALSE on failure. Closing a device will fail if the device contains any contexts or buffers.

See Also

alcOpenDevice

Context Extension Functions

Functions

alcIsExtensionPresent

Description

This function queries if a specified context extension is available.

ALCboolean alcIsExtensionPresent(
    ALCdevice *device,
    const ALCchar *extName
);
Parameters
  • device - A pointer to the device to be queried for an extension
  • extName - A null-terminated string describing the extension
Possible Error States
State Description
ALC_INVALID_VALUE The string pointer is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns ALC_TRUE if the extension is available, ALC_FALSE if the extension is not available.

See Also

alcGetProcAddress, alcGetEnumValue

alcGetProcAddress

Description

This function retrieves the address of a specified context extension function.

void* alcGetProcAddress(
    ALCdevice* device,
    const ALCchar* funcName
);
Parameters
  • device - A pointer to the device to be queried for the function
  • funcName - a null-terminated string describing the function
Possible Error States
State Description
ALC_INVALID_VALUE The string pointer is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns the address of the function, or NULL if it is not found.

See Also

alcIsExtensionPresent, alcGetEnumValue

alcGetEnumValue

Description

This function retrieves the enum value for a specified enumeration name.

ALCenum alcGetEnumValue(
    ALCdevice* device,
    const ALCchar* enumName
);
Parameters
  • device - A pointer to the device to be queried
  • enumName - A null terminated string describing the enum value
Possible Error States
State Description
ALC_INVALID_VALUE The string pointer is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

Returns the enum value described by the enumName string. This is most often used for querying an enum value for an ALC extension.

See Also

alcIsExtensionPresent, alcGetProcAddress

Context State Functions

Functions

alcGetString

Description

This function returns pointers to strings related to the context.

const ALCchar * alcGetString(
    ALCdevice *device,
    ALenum param
);
Parameters
  • device - A pointer to the device to be queried
  • param - An attribute to be retrieved:
    • ALC_DEFAULT_DEVICE_SPECIFIER
    • ALC_CAPTURE_DEFAULT_DEVICE_SPECIFIER
    • ALC_DEVICE_SPECIFIER
    • ALC_CAPTURE_DEVICE_SPECIFIER
    • ALC_EXTENSIONS
Possible Error States
State Description
ALC_INVALID_ENUM The specified parameter is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

ALC_DEFAULT_DEVICE_SPECIFIER will return the name of the default output device.

ALC_CAPTURE_DEFAULT_DEVICE_SPECIFIER will return the name of the default capture device.

ALC_DEVICE_SPECIFIER will return the name of the specified output device if a pointer is supplied, or will return a list of all available devices if a NULL device pointer is supplied. A list is a pointer to a series of strings separated by NULL characters, with the list terminated by two NULL characters. See Enumeration Extension for more details.

ALC_CAPTURE_DEVICE_SPECIFIER will return the name of the specified capture device if a pointer is supplied, or will return a list of all available devices if a NULL device pointer is supplied.

ALC_EXTENSIONS returns a list of available context extensions, with each extension separated by a space and the list terminated by a NULL character.

alcGetIntegerv

Description

This function returns integers related to the context.

void alcGetIntegerv(
    ALCdevice* device,
    ALCenum param,
    ALCsizei size,
    ALCint* data
);
Parameters
  • device - A pointer to the device to be queried
  • param - An attribute to be retrieved:
    • ALC_MAJOR_VERSION
    • ALC_MINOR_VERSION
    • ALC_ATTRIBUTES_SIZE
    • ALC_ALL_ATTRIBUTES
  • size - The size of the destination buffer provided
  • data - A pointer to the data to be returned
Possible Error States
State Description
ALC_INVALID_VALUE The specified data pointer or size is not valid.
ALC_INVALID_ENUM The specified parameter is not valid.
ALC_INVALID_DEVICE The specified device is not valid.
ALC_INVALID_CONTEXT The specified context is not valid.
Version Requirements

OpenAL 1.0 or higher

Remarks

The versions returned refer to the specification version that the implementation meets.

Context Capture Functions

Functions

alcCaptureOpenDevice

Description

This function opens a capture device by name.

ALCdevice* alcCaptureOpenDevice(
    const ALCchar* devicename,
    ALCuint frequency,
    ALCenum format,
    ALCsizei buffersize
);
Parameters
  • devicename - A pointer to a device name string
  • frequency - The frequency that the data should be captured at
  • format - The requested capture buffer format
  • buffersize - The size of the capture buffer
Possible Error States
State Description
ALC_INVALID_VALUE One of the parameters has an invalid value.
ALC_OUT_OF_MEMORY The specified device is invalid, or can not capture audio.
Version Requirements

OpenAL 1.1 or higher

Remarks

Returns the capture device pointer, or NULL on failure.

See Also

alcCaptureCloseDevice

alcCaptureCloseDevice

Description

This function closes the specified capture device.

ALCboolean alcCaptureCloseDevice(
    ALCdevice* device
);
Parameters
  • device - A pointer to a capture device
Possible Error States
State Description
ALC_INVALID_DEVICE The specified device is not a valid capture device.
Version Requirements

OpenAL 1.1 or higher

Remarks

Returns ALC_TRUE if the close operation was successful, ALC_FALSE on failure.

See Also

alcCaptureOpenDevice

alcCaptureStart

Description

This function begins a capture operation.

void alcCaptureStart(
    ALCdevice *device
);
Parameters
  • device - A pointer to a capture device
Possible Error States
State Description
ALC_INVALID_DEVICE The specified device is not a valid capture device.
Version Requirements

OpenAL 1.1 or higher

Remarks

alcCaptureStart will begin recording to an internal ring buffer of the size specified when opening the capture device. The application can then retrieve the number of samples currently available using the ALC_CAPTURE_SAMPLES token with alcGetIntegerv. When the application determines that enough samples are available for processing, then it can obtain them with a call to alcCaptureSamples.

See Also

alcCaptureStop, alcCaptureSamples

alcCaptureStop

Description

This function stops a capture operation.

void alcCaptureStop(
    ALCdevice *device
);
Parameters
  • device - A pointer to a capture device
Possible Error States
State Description
ALC_INVALID_DEVICE The specified device is not a valid capture device.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alcCaptureStart, alcCaptureSamples

alcCaptureSamples

Description

This function completes a capture operation, and does not block.

void alcCaptureSamples(
    ALCdevice* device,
    ALCvoid* buffer,
    ALCsizei samples
);
Parameters
  • device - A pointer to a capture device
  • buffer - A pointer to a data buffer, which must be large enough to accommodate samples number of samples
  • samples - The number of samples to be retrieved
Possible Error States
State Description
ALC_INVALID_VALUE The specified number of samples is larger than the number of available samples.
ALC_INVALID_DEVICE The specified device is not a valid capture device.
Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alcCaptureStart, alcCaptureStop

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