Programmer's Guide (original) (raw)

OpenAL Programmer's Guide - Versions 1.0 and 1.1

Table of Contents

• About this Document
  • Introduction
  • Intended Audience
  • Other OpenAL Resources
• Introduction to OpenAL
  • Objects
  • Device Enumeration
  • Initializing/Exiting
  • Listener properties
  • Buffer Properties
  • Source Properties
  • Queuing Buffers on a Source
  • Doppler Shift
  • Error Handling
  • Extensions
• Buffer Functions
  • Properties
  • Functions
• Source Functions
  • Properties
  • Functions
• Listener Functions
  • Properties
  • Functions
• State Functions
  • Properties
  • Functions
• Error Functions
  • Error Codes
  • Functions
• Extension Functions
  • Functions
• Context Management Functions
  • Properties
  • Functions
• Context Error Functions
  • Error Codes
  • Functions
• Context Device Functions
  • Functions
• Context Extension Functions
  • Functions
• Context State Functions
  • Functions
• Context Capture Functions
  • Functions

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:

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 andALC_DEFAULT_DEVICE_SPECIFIER.

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

The programmer can find out more about the capabilities of each device by querying to see which extensions it supports usingalcIsExtensionPresent andalIsExtensionPresent.

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, andalGetSource3f.

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. ThealListener[f, 3f, fv, i] and alGetListener[f, 3f, fv, i] families of functions can be used to set or retrieve the following listener properties:

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:

Example:

// Retrieve Buffer Frequency alGetBufferi(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] andalGetSource[f, 3f, fv, i] families of functions can be used to set or retrieve the following source properties:

* 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 functionsalSourceQueueBuffers andalSourceUnqueueBuffers are used. The program can attach a buffer or a set of buffers to a source usingalSourceQueueBuffers, and then callalSourcePlay 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 usealSourceQueueBuffers to attach buffers to streaming sources. Any source can have all buffers detached from it usingalSourcei(..., 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 (withalSourcei or with alSourceQueueBuffers).
2. All buffers attached to a source usingalSourceQueueBuffers 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:

3D Mathematical representation of vls and vss: left∣vright∣=\left | v \right | = \left∣vright∣=\sqrt{v.x \times v.x + v.y \times v.y + v.z \times v.z}$ v1bulletv2=v1.xtimesv2.x+v1.ytimesv2.y+v1.ztimesv2.zv1 \bullet v2 = v1.x \times v2.x + v1.y \times v2.y + v1.z \times v2.zv1bulletv2=v1.xtimesv2.x+v1.ytimesv2.y+v1.ztimesv2.z vls=min(fracSLbulletLVleft∣SLright∣,fracSSDF)vls = \min{( \frac{SL \bullet LV}{\left | SL \right |}, \frac{SS}{DF} )}vls=min(fracSLbulletLVleft∣SLright∣,fracSSDF) vss=min(fracSLbulletSVleft∣SLright∣,fracSSDF)vss = \min{( \frac{SL \bullet SV}{\left | SL \right |}, \frac{SS}{DF} )}vss=min(fracSLbulletSVleft∣SLright∣,fracSSDF) f′=ftimesfracSS−DFtimesvlsSS−DFtimesvss{f}' = f \times \frac{SS - DF \times vls}{SS - DF \times vss}f′=ftimesfracSS−DFtimesvlsSS−DFtimesvss

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 usingalGetFloat{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 usingalGetError. alGetError clears the error state of OpenAL when it is called, so it is common for an OpenAL application to callalGetError at the beginning of a critical operation to clear the error state, perform the critical operation, and then usealGetError again to test whether or not an error occurred.

Error Codes:

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 eitheralIsExtensionPresent oralcIsExtensionPresent depending on the type of extension. The Appendices contain more details about some of Creative’s extensions to OpenAL.

Buffer Functions

Properties

Functions

• alGenBuffers
• alDeleteBuffers
• alIsBuffer
• alBufferData
• alBufferf
• alBuffer3f
• alBufferfv
• alBufferi
• alBuffer3i
• alBufferiv
• alGetBufferf
• alGetBuffer3f
• alGetBufferfv
• alGetBufferi
• alGetBuffer3i
• alGetBufferiv

alGenBuffers

Description

This function generates one or more buffers, which contain audio data (seealBufferData). References to buffers are ALuint values, which are used wherever a buffer reference is needed (in calls such asalDeleteBuffers, alSourcei,alSourceQueueBuffers, andalSourceUnqueueBuffers).

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

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, alGenBuffersdoes 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. SeealSourcei and alSourceUnqueueBuffersfor 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

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

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

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

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

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

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

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

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

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

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

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
• value - Pointer to an ALint to hold the retrieved data

Possible Error States

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

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
• values - Pointer to an ALint vector to hold the retrieved data

Possible Error States

Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alBufferi, alBuffer3i,alBufferiv, alGetBufferi,alGetBuffer3i

Source Functions

Properties

Functions

• alGenSources
• alDeleteSources
• alIsSource
• alSourcef
• alSource3f
• alSourcefv
• alSourcei
• alSource3i
• alSourceiv
• alGetSourcef
• alGetSource3f
• alGetSourcefv
• alGetSourcei
• alGetSource3i
• alGetSourceiv
• alSourcePlay
• alSourcePlayv
• alSourcePause
• alSourcePausev
• alSourceStop
• alSourceStopv
• alSourceRewind
• alSourceRewindv
• alSourceQueueBuffers
• alSourceUnqueueBuffers

alGenSources

Description

This function generates one or more sources. References to sources areALuint 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

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, alGenSourcesdoes 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

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 andAL_FALSE if not.

boolean alIsSource( ALuint source );

Parameters

• source - A source name to be tested for validity

Possible Error States

Version Requirements

OpenAL 1.0 or higher

Remarks

None

See Also

alGenSources, alDeleteSources

alSourcef

Description

This function sets a floating-point 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

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

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

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

Version Requirements

OpenAL 1.0 or higher

Remarks

The buffer name zero is reserved as a “NULL Buffer" and is accepted byalSourcei(…, AL_BUFFER, …) as a valid buffer of zero length. The NULLBuffer 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

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

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

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

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

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

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 theAL_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

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 theAL_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

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

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

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

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

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

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 alGetSourcei call to retrieveAL_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

Version Requirements

OpenAL 1.0 or higher

Remarks

When first created, a source will be of type AL_UNDETERMINED. A successfulalSourceQueueBuffers 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

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

Functions

• alListenerf
• alListener3f
• alListenerfv
• alListeneri
• alListener3i
• alListeneriv
• alGetListenerf
• alGetListener3f
• alGetListenerfv
• alGetListeneri
• alGetListener3i
• alGetListeneriv

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

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

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

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

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

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

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

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

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

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

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

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

Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alListeneri, alListener3i,alListeneriv, alGetListeneri,alGetListener3i

State Functions

Properties

Functions

• alEnable
• alDisable
• alIsEnabled
• alGetBoolean
• alGetDouble
• alGetFloat
• alGetInteger
• alGetBooleanv
• alGetDoublev
• alGetFloatv
• alGetIntegerv
• alGetString
• alDistanceModel
• alDopplerFactor
• alSpeedOfSound

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

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

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

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

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

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

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

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

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

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

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

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

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:

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:

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:

The AL_NONE distance model works according to the following formula:

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

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

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

Version Requirements

OpenAL 1.1 or higher

Remarks

The default speed of sound value is 343.3.

Error Functions

Error Codes

Functions

• alGetError

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 alGetErroris 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
• alGetProcAddress
• alGetEnumValue

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

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

Functions

• alcCreateContext
• alcMakeContextCurrent
• alcProcessContext
• alcSuspendContext
• alcDestroyContext
• alcGetCurrentContext
• alcGetContextsDevice

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

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

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

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

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 alcSuspendContextwould 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

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 foralcMakeContextCurrent).

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

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

Functions

• alcGetError

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
• alcCloseDevice

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

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
• alcGetProcAddress
• alcGetEnumValue

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

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

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

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
• alcGetIntegerv

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

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 NULLdevice pointer is supplied. A list is a pointer to a series of strings separated by NULL characters, with the list terminated by two NULLcharacters. 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

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
• alcCaptureCloseDevice
• alcCaptureStart
• alcCaptureStop
• alcCaptureSamples

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

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

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

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 theALC_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

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

Version Requirements

OpenAL 1.1 or higher

Remarks

None

See Also

alcCaptureStart, alcCaptureStop