Programmer's Guide

OpenAL Programmer's Guide - Versions 1.0 and 1.1

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:

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).
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

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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

Programmer's Guide

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

alGenBuffers

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alDeleteBuffers

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alIsBuffer

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alBufferData

Description

Parameters

Possible Error States

Version Requirements

Remarks

alBufferf

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alBuffer3f

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alBufferfv

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alBufferi

Description

Parameters

Possible Error States

Version Requirements

Remarks

See Also

alBuffer3i

Description

Parameters

Possible Error States