# Audio addon

These functions are declared in the following header file.
Link with allegro_audio.

~~~~c
 #include <allegro5/allegro_audio.h>
~~~~

## Audio types

### API: ALLEGRO_AUDIO_DEPTH

Sample depth and type, and signedness. Mixers only use 32-bit signed
float (-1..+1), or 16-bit signed integers.
The unsigned value is a bit-flag applied to the depth value.

* ALLEGRO_AUDIO_DEPTH_INT8
* ALLEGRO_AUDIO_DEPTH_INT16
* ALLEGRO_AUDIO_DEPTH_INT24
* ALLEGRO_AUDIO_DEPTH_FLOAT32
* ALLEGRO_AUDIO_DEPTH_UNSIGNED

For convenience:

* ALLEGRO_AUDIO_DEPTH_UINT8
* ALLEGRO_AUDIO_DEPTH_UINT16
* ALLEGRO_AUDIO_DEPTH_UINT24

### API: ALLEGRO_AUDIO_PAN_NONE

A special value for the pan property of samples and audio streams.
Use this value to disable panning on samples and audio streams, and play
them without attentuation implied by panning support.

ALLEGRO_AUDIO_PAN_NONE is different from a pan value of 0.0 (centered) because,
when panning is enabled, we try to maintain a constant sound power level as a
sample is panned from left to right.  A sound coming out of one speaker
should sound as loud as it does when split over two speakers.
As a consequence, a sample with pan value 0.0 will be 3 dB softer than the
original level.

(Please correct us if this is wrong.)

### API: ALLEGRO_CHANNEL_CONF

Speaker configuration (mono, stereo, 2.1, etc).

* ALLEGRO_CHANNEL_CONF_1
* ALLEGRO_CHANNEL_CONF_2
* ALLEGRO_CHANNEL_CONF_3
* ALLEGRO_CHANNEL_CONF_4
* ALLEGRO_CHANNEL_CONF_5_1
* ALLEGRO_CHANNEL_CONF_6_1
* ALLEGRO_CHANNEL_CONF_7_1

### API: ALLEGRO_MIXER

A mixer is a type of stream which mixes together attached streams into a
single buffer.

### API: ALLEGRO_MIXER_QUALITY

* ALLEGRO_MIXER_QUALITY_POINT - point sampling
* ALLEGRO_MIXER_QUALITY_LINEAR - linear interpolation
* ALLEGRO_MIXER_QUALITY_CUBIC - cubic interpolation (since: 5.0.8, 5.1.4)

### API: ALLEGRO_PLAYMODE

Sample and stream playback mode.

* ALLEGRO_PLAYMODE_ONCE
* ALLEGRO_PLAYMODE_LOOP
* ALLEGRO_PLAYMODE_BIDIR

### API: ALLEGRO_SAMPLE_ID

An ALLEGRO_SAMPLE_ID represents a sample being played via [al_play_sample].
It can be used to later stop the sample with [al_stop_sample].

### API: ALLEGRO_SAMPLE

An ALLEGRO_SAMPLE object stores the data necessary for playing
pre-defined digital audio. It holds information pertaining to data length,
frequency, channel configuration, etc.  You can have an ALLEGRO_SAMPLE
object playing multiple times simultaneously.  The object holds a
user-specified PCM data buffer, of the format the object is created with.

See also: [ALLEGRO_SAMPLE_INSTANCE]

### API: ALLEGRO_SAMPLE_INSTANCE

An ALLEGRO_SAMPLE_INSTANCE object represents a playable instance
of a predefined sound effect.
It holds information pertaining to the looping mode, loop
start/end points, playing position, etc.  An instance uses the
data from an [ALLEGRO_SAMPLE] object.  Multiple instances may be created
from the same ALLEGRO_SAMPLE. An ALLEGRO_SAMPLE must not be
destroyed while there are instances which reference it.

To be played, an ALLEGRO_SAMPLE_INSTANCE object must be attached to an
[ALLEGRO_VOICE] object,
or to an [ALLEGRO_MIXER] object which is itself attached to an
ALLEGRO_VOICE object (or to another ALLEGRO_MIXER object which is attached
to an ALLEGRO_VOICE object, etc).

See also: [ALLEGRO_SAMPLE]

### API: ALLEGRO_AUDIO_STREAM

An ALLEGRO_AUDIO_STREAM object is used to stream generated audio to the sound
device, in real-time. This is done by reading from a buffer, which is split
into a number of fragments. Whenever a fragment has finished playing, the
user can refill it with new data.

As with [ALLEGRO_SAMPLE_INSTANCE] objects, streams store information necessary
for playback, so you may not play the same stream multiple times simultaneously.
Streams also need to be attached to an [ALLEGRO_VOICE] object, or to an
[ALLEGRO_MIXER] object which, eventually, reaches an ALLEGRO_VOICE object.

While playing, you must periodically fill fragments with new audio data. To
know when a new fragment is ready to be filled, you can either directly check
with [al_get_available_audio_stream_fragments], or listen to events from the
stream.

You can register an audio stream event source to an event queue; see
[al_get_audio_stream_event_source].  An ALLEGRO_EVENT_AUDIO_STREAM_FRAGMENT
event is generated whenever a new fragment is ready.  When you receive an
event, use [al_get_audio_stream_fragment] to obtain a pointer to the fragment
to be filled. The size and format are determined by the parameters passed to
[al_create_audio_stream].

If you're late with supplying new data, the stream will be silent until new data
is provided. You must call [al_drain_audio_stream] when you're finished with
supplying data to the stream.

If the stream is created by [al_load_audio_stream] then it can also generate an
ALLEGRO_EVENT_AUDIO_STREAM_FINISHED event if it reaches the end of the file and
is not set to loop.

### API: ALLEGRO_VOICE

A voice represents an audio device on the system, which may be a real device,
or an abstract device provided by the operating system.
To play back audio, you would attach a mixer or sample or stream to a voice.

See also: [ALLEGRO_MIXER], [ALLEGRO_SAMPLE], [ALLEGRO_AUDIO_STREAM]


## Setting up audio

### API: al_install_audio

Install the audio subsystem.

Returns true on success, false on failure.

Note: most users will call [al_reserve_samples] and [al_init_acodec_addon]
after this.

See also: [al_reserve_samples], [al_uninstall_audio], [al_is_audio_installed],
[al_init_acodec_addon]

### API: al_uninstall_audio

Uninstalls the audio subsystem.

See also: [al_install_audio]

### API: al_is_audio_installed

Returns true if [al_install_audio] was called previously and returned
successfully.

### API: al_reserve_samples

Reserves a number of sample instances, attaching them to the default mixer.
If no default mixer is set when this function is called, then it will
automatically create a voice with an attached mixer, which becomes the default
mixer.  This diagram illustrates the structures that are set up:

                                  sample instance 1
                                / sample instance 2
    voice <-- default mixer <---         .
                                \        .
                                  sample instance N

Returns true on success, false on error.
[al_install_audio] must have been called first.

See also: [al_set_default_mixer], [al_play_sample]


## Misc audio functions

### API: al_get_allegro_audio_version

Returns the (compiled) version of the addon, in the same format as
[al_get_allegro_version].

### API: al_get_audio_depth_size

Return the size of a sample, in bytes, for the given format. The format is one
of the values listed under [ALLEGRO_AUDIO_DEPTH].

### API: al_get_channel_count

Return the number of channels for the given channel configuration, which is one
of the values listed under [ALLEGRO_CHANNEL_CONF].


## Voice functions

### API: al_create_voice

Creates a voice structure and allocates a voice from the digital sound driver.
The passed frequency, sample format and channel configuration are used as a
hint to what kind of data will be sent to the voice. However, the underlying
sound driver is free to use non-matching values. For example it may be the
native format of the sound hardware. If a mixer is attached to the voice, the
mixer will convert from the mixer's format to the voice format and care does
not have to be taken for this.

However if you access the voice directly, make sure to not rely on the
parameters passed to this function, but instead query the returned voice for
the actual settings.

See also: [al_destroy_voice]

### API: al_destroy_voice

Destroys the voice and deallocates it from the digital driver.
Does nothing if the voice is NULL.

See also: [al_create_voice]

### API: al_detach_voice

Detaches the mixer or sample or stream from the voice.

See also: [al_attach_mixer_to_voice], [al_attach_sample_instance_to_voice],
[al_attach_audio_stream_to_voice]

### API: al_attach_audio_stream_to_voice

Attaches an audio stream to a voice. The same rules as
[al_attach_sample_instance_to_voice] apply. This may fail if the driver can't create
a voice with the buffer count and buffer size the stream uses.

An audio stream attached directly to a voice has a number of limitations.  The
audio stream plays immediately and cannot be stopped. The stream position,
speed, gain, panning, cannot be changed.  At this time, we don't recommend
attaching audio streams directly to voices.  Use a mixer in between.

Returns true on success, false on failure.

See also: [al_detach_voice]

### API: al_attach_mixer_to_voice

Attaches a mixer to a voice. The same rules as [al_attach_sample_instance_to_voice]
apply, with the exception of the depth requirement.

Returns true on success, false on failure.

See also: [al_detach_voice]

### API: al_attach_sample_instance_to_voice

Attaches a sample to a voice, and allows it to play. The sample's volume
and loop mode will be ignored, and it must have the same frequency and
depth (including signed-ness) as the voice. This function may fail if the
selected driver doesn't support preloading sample data.

At this time, we don't recommend attaching samples directly to voices.
Use a mixer in between.

Returns true on success, false on failure.

See also: [al_detach_voice]

### API: al_get_voice_frequency

Return the frequency of the voice, e.g. 44100.

### API: al_get_voice_channels

Return the channel configuration of the voice.

See also: [ALLEGRO_CHANNEL_CONF].

### API: al_get_voice_depth

Return the audio depth of the voice.

See also: [ALLEGRO_AUDIO_DEPTH].

### API: al_get_voice_playing

Return true if the voice is currently playing.

See also: [al_set_voice_playing]

### API: al_set_voice_playing

Change whether a voice is playing or not.
This can only work if the voice has a non-streaming
object attached to it, e.g. a sample instance.
On success the voice's current sample position is reset.

Returns true on success, false on failure.

See also: [al_get_voice_playing]

### API: al_get_voice_position

When the voice has a non-streaming object attached to it, e.g. a sample,
returns the voice's current sample position.
Otherwise, returns zero.

See also: [al_set_voice_position].

### API: al_set_voice_position

Set the voice position.  This can only work if the voice has a non-streaming
object attached to it, e.g. a sample instance.

Returns true on success, false on failure.

See also: [al_get_voice_position].


## Sample functions

### API: al_create_sample

Create a sample data structure from the supplied buffer.
If `free_buf` is true then the buffer will be freed with [al_free] when the
sample data structure is destroyed.  For portability (especially Windows),
the buffer should have been allocated with [al_malloc].  Otherwise you should
free the sample data yourself.

To allocate a buffer of the correct size, you can use something like this:

~~~~c
int sample_size = al_get_channel_count(chan_conf)
                  * al_get_audio_depth_size(depth);
int bytes = samples * sample_size;
void *buffer = al_malloc(bytes);
~~~~

See also: [al_destroy_sample], [ALLEGRO_AUDIO_DEPTH], [ALLEGRO_CHANNEL_CONF]

### API: al_destroy_sample

Free the sample data structure. If it was created with the `free_buf`
parameter set to true, then the buffer will be freed with [al_free].

This function will stop any sample instances which may be playing the
buffer referenced by the [ALLEGRO_SAMPLE].

See also: [al_destroy_sample_instance], [al_stop_sample], [al_stop_samples]

### API: al_play_sample

Plays a sample on one of the sample instances created by [al_reserve_samples].
Returns true on success, false on failure.
Playback may fail because all the reserved sample instances are currently used.

Parameters:

* gain - relative volume at which the sample is played; 1.0 is normal.
* pan - 0.0 is centred, -1.0 is left, 1.0 is right, or ALLEGRO_AUDIO_PAN_NONE.
* speed - relative speed at which the sample is played; 1.0 is normal.
* loop - ALLEGRO_PLAYMODE_ONCE, ALLEGRO_PLAYMODE_LOOP, or ALLEGRO_PLAYMODE_BIDIR
* ret_id - if non-NULL the variable which this points to will be assigned
  an id representing the sample being played.

See also: [ALLEGRO_PLAYMODE], [ALLEGRO_AUDIO_PAN_NONE], [ALLEGRO_SAMPLE_ID],
[al_stop_sample], [al_stop_samples].

### API: al_stop_sample

Stop the sample started by [al_play_sample].

See also: [al_stop_samples]

### API: al_stop_samples

Stop all samples started by [al_play_sample].

See also: [al_stop_sample]

### API: al_get_sample_channels

Return the channel configuration.

See also: [ALLEGRO_CHANNEL_CONF], [al_get_sample_depth],
[al_get_sample_frequency], [al_get_sample_length], [al_get_sample_data]

### API: al_get_sample_depth

Return the audio depth.

See also: [ALLEGRO_AUDIO_DEPTH], [al_get_sample_channels],
[al_get_sample_frequency], [al_get_sample_length], [al_get_sample_data]

### API: al_get_sample_frequency

Return the frequency of the sample.

See also: [al_get_sample_channels], [al_get_sample_depth],
[al_get_sample_length], [al_get_sample_data]

### API: al_get_sample_length

Return the length of the sample in sample values.

See also: [al_get_sample_channels], [al_get_sample_depth],
[al_get_sample_frequency], [al_get_sample_data]

### API: al_get_sample_data

Return a pointer to the raw sample data.

See also: [al_get_sample_channels], [al_get_sample_depth],
[al_get_sample_frequency], [al_get_sample_length]


## Sample instance functions

### API: al_create_sample_instance

Creates a sample stream, using the supplied data.  This must be attached
to a voice or mixer before it can be played.
The argument may be NULL. You can then set the data later with
[al_set_sample].

See also: [al_destroy_sample_instance]

### API: al_destroy_sample_instance

Detaches the sample stream from anything it may be attached to and frees
it (the sample data is *not* freed!).

See also: [al_create_sample_instance]

### API: al_play_sample_instance

Play an instance of a sample data.
Returns true on success, false on failure.

See also: [al_stop_sample_instance]

### API: al_stop_sample_instance

Stop an sample instance playing.

See also: [al_play_sample_instance]

### API: al_get_sample_instance_channels

Return the channel configuration.

See also: [ALLEGRO_CHANNEL_CONF].

### API: al_get_sample_instance_depth

Return the audio depth.

See also: [ALLEGRO_AUDIO_DEPTH].

### API: al_get_sample_instance_frequency

Return the frequency of the sample instance.

### API: al_get_sample_instance_length

Return the length of the sample instance in sample values.

See also: [al_set_sample_instance_length], [al_get_sample_instance_time]

### API: al_set_sample_instance_length

Set the length of the sample instance in sample values.

Return true on success, false on failure.  Will fail if the sample instance is
currently playing.

See also: [al_get_sample_instance_length]

### API: al_get_sample_instance_position

Get the playback position of a sample instance.

See also: [al_set_sample_instance_position]

### API: al_set_sample_instance_position

Set the playback position of a sample instance.

Returns true on success, false on failure.

See also: [al_get_sample_instance_position]

### API: al_get_sample_instance_speed

Return the relative playback speed.

See also: [al_set_sample_instance_speed]

### API: al_set_sample_instance_speed

Set the relative playback speed.  1.0 is normal speed.

Return true on success, false on failure.  Will fail if the sample instance is
attached directly to a voice.

See also: [al_get_sample_instance_speed]

### API: al_get_sample_instance_gain

Return the playback gain.

See also: [al_set_sample_instance_gain]

### API: al_set_sample_instance_gain

Set the playback gain.

Returns true on success, false on failure.  Will fail if the sample instance
is attached directly to a voice.

See also: [al_get_sample_instance_gain]

### API: al_get_sample_instance_pan

Get the pan value.

See also: [al_set_sample_instance_pan].

### API: al_set_sample_instance_pan

Set the pan value on a sample instance.  A value of -1.0 means to play the
sample only through the left speaker; +1.0 means only through the right
speaker; 0.0 means the sample is centre balanced.
A special value [ALLEGRO_AUDIO_PAN_NONE] disables panning and plays the
sample at its original level.  This will be louder than a pan value of 0.0.

> Note: panning samples with more than two channels doesn't work yet.

Returns true on success, false on failure.
Will fail if the sample instance is attached directly to a voice.

See also: [al_get_sample_instance_pan], [ALLEGRO_AUDIO_PAN_NONE]

### API: al_get_sample_instance_time

Return the length of the sample instance in seconds,
assuming a playback speed of 1.0.

See also: [al_get_sample_instance_length]

### API: al_get_sample_instance_playmode

Return the playback mode.

See also: [ALLEGRO_PLAYMODE], [al_set_sample_instance_playmode]

### API: al_set_sample_instance_playmode

Set the playback mode.

Returns true on success, false on failure.

See also: [ALLEGRO_PLAYMODE], [al_get_sample_instance_playmode]

### API: al_get_sample_instance_playing

Return true if the sample instance is playing.

See also: [al_set_sample_instance_playing]

### API: al_set_sample_instance_playing

Change whether the sample instance is playing.

Returns true on success, false on failure.

See also: [al_get_sample_instance_playing]

### API: al_get_sample_instance_attached

Return whether the sample instance is attached to something.

See also: [al_attach_sample_instance_to_mixer],
[al_attach_sample_instance_to_voice], [al_detach_sample_instance]

### API: al_detach_sample_instance

Detach the sample instance from whatever it's attached to,
if anything.

Returns true on success.

See also: [al_attach_sample_instance_to_mixer],
[al_attach_sample_instance_to_voice], [al_get_sample_instance_attached]

### API: al_get_sample

Return the sample data that the sample instance plays.

Note this returns a pointer to an internal structure, *not* the
[ALLEGRO_SAMPLE] that you may have passed to [al_set_sample].
You may, however, check which sample buffer is being played by the sample
instance with [al_get_sample_data], and so on.

See also: [al_set_sample]

### API: al_set_sample

Change the sample data that a sample instance plays.  This can be quite an
involved process.

First, the sample is stopped if it is not already.

Next, if data is NULL, the sample is detached from its parent (if any).

If data is not NULL, the sample may be detached and reattached to its
parent (if any).  This is not necessary if the old sample data and new
sample data have the same frequency, depth and channel configuration.
Reattaching may not always succeed.

On success, the sample remains stopped.  The playback position and loop
end points are reset to their default values.  The loop mode remains
unchanged.

Returns true on success, false on failure.  On failure, the sample will
be stopped and detached from its parent.

See also: [al_get_sample]


## Mixer functions

### API: al_create_mixer

Creates a mixer stream, to attach sample streams or other mixers to. It
will mix into a buffer at the requested frequency and channel count.

The only supported audio depths are ALLEGRO_AUDIO_DEPTH_FLOAT32
and ALLEGRO_AUDIO_DEPTH_INT16 (not yet complete).

Returns true on success, false on error.

See also: [al_destroy_mixer], [ALLEGRO_AUDIO_DEPTH], [ALLEGRO_CHANNEL_CONF]

### API: al_destroy_mixer

Destroys the mixer stream.

See also: [al_create_mixer]

### API: al_get_default_mixer

Return the default mixer, or NULL if one has not been set.
Although different configurations of mixers and voices can be used, in
most cases a single mixer attached to a voice is what you want.
The default mixer is used by [al_play_sample].

See also: [al_reserve_samples], [al_play_sample], [al_set_default_mixer],
[al_restore_default_mixer]

### API: al_set_default_mixer

Sets the default mixer. All samples started with [al_play_sample]
will be stopped. If you are using your own mixer, this should be
called before [al_reserve_samples].

Returns true on success, false on error.

See also: [al_reserve_samples], [al_play_sample], [al_get_default_mixer],
[al_restore_default_mixer]

### API: al_restore_default_mixer

Restores Allegro's default mixer. All samples started with [al_play_sample]
will be stopped.
Returns true on success, false on error.

See also: [al_get_default_mixer], [al_set_default_mixer], [al_reserve_samples].

### API: al_attach_mixer_to_mixer

Attaches the mixer passed as the first argument onto the mixer passed as the
second argument. The same rules as with [al_attach_sample_instance_to_mixer]
apply, with the added caveat that both mixers must be the same frequency.
Returns true on success, false on error.

Currently both mixers must have the same audio depth, otherwise the function
fails.

See also: [al_detach_mixer].

### API: al_attach_sample_instance_to_mixer

Attach a sample instance to a mixer.  The instance must not already be attached
to anything.

Returns true on success, false on failure.

See also: [al_detach_sample_instance].

### API: al_attach_audio_stream_to_mixer

Attach a stream to a mixer.

Returns true on success, false on failure.

See also: [al_detach_audio_stream].

### API: al_get_mixer_frequency

Return the mixer frequency.

See also: [al_set_mixer_frequency]

### API: al_set_mixer_frequency

Set the mixer frequency.  This will only work if the mixer is not attached to
anything.

Returns true on success, false on failure.

See also: [al_get_mixer_frequency]

### API: al_get_mixer_channels

Return the mixer channel configuration.

See also: [ALLEGRO_CHANNEL_CONF].

### API: al_get_mixer_depth

Return the mixer audio depth.

See also: [ALLEGRO_AUDIO_DEPTH].

### API: al_get_mixer_gain

Return the mixer gain (amplification factor). The default is 1.0.

Since: 5.0.6, 5.1.0

See also: [al_set_mixer_gain].

### API: al_set_mixer_gain

Set the mixer gain (amplification factor).

Returns true on success, false on failure.

Since: 5.0.6, 5.1.0

See also: [al_get_mixer_gain]

### API: al_get_mixer_quality

Return the mixer quality.

See also: [ALLEGRO_MIXER_QUALITY], [al_set_mixer_quality]

### API: al_set_mixer_quality

Set the mixer quality.  This can only succeed if the mixer does not have
anything attached to it.

Returns true on success, false on failure.

See also: [ALLEGRO_MIXER_QUALITY], [al_get_mixer_quality]

### API: al_get_mixer_playing

Return true if the mixer is playing.

See also: [al_set_mixer_playing].

### API: al_set_mixer_playing

Change whether the mixer is playing.

Returns true on success, false on failure.

See also: [al_get_mixer_playing].

### API: al_get_mixer_attached

Return true if the mixer is attached to something.

See also: [al_attach_sample_instance_to_mixer], [al_attach_audio_stream_to_mixer],
[al_attach_mixer_to_mixer], [al_detach_mixer]

### API: al_detach_mixer

Detach the mixer from whatever it is attached to, if anything.

See also: [al_attach_mixer_to_mixer].

### API: al_set_mixer_postprocess_callback

Sets a post-processing filter function that's called after the attached
streams have been mixed. The buffer's format will be whatever the mixer
was created with. The sample count and user-data pointer is also passed.



## Stream functions

### API: al_create_audio_stream

Creates an [ALLEGRO_AUDIO_STREAM]. The stream will be set to play by default.
It will feed audio data from a buffer, which is split into a number of
fragments.

Parameters:

* fragment_count - How many fragments to use for the audio stream.
    Usually only two fragments are required - splitting the audio buffer in
    two halves. But it means that the only time when new data can be supplied
    is whenever one half has finished playing.  When using many fragments,
    you usually will use fewer samples for one, so there always will be
    (small) fragments available to be filled with new data.

* frag_samples - The size of a fragment in samples. See note below.

* freq - The frequency, in Hertz.

* depth - Must be one of the values listed for [ALLEGRO_AUDIO_DEPTH].

* chan_conf - Must be one of the values listed for [ALLEGRO_CHANNEL_CONF].

The choice of *fragment_count*, *frag_samples* and *freq* directly influences
the audio delay. The delay in seconds can be expressed as:

    delay = fragment_count * frag_samples / freq

This is only the delay due to Allegro's streaming, there may be additional
delay caused by sound drivers and/or hardware.

> *Note:* If you know the fragment size in bytes, you can get the size in samples
> like this:
>
>     sample_size = al_get_channel_count(chan_conf) * al_get_audio_depth_size(depth);
>     samples = bytes_per_fragment / sample_size;
>
> The size of the complete buffer is:
>
>     buffer_size = bytes_per_fragment * fragment_count

> *Note:* unlike many Allegro objects, audio streams are not implicitly destroyed
when Allegro is shut down.  You must destroy them manually with
[al_destroy_audio_stream] before the audio system is shut down.

### API: al_destroy_audio_stream

Destroy an audio stream which was created with [al_create_audio_stream]
or [al_load_audio_stream].

> *Note:* If the stream is still attached to a mixer or voice,
[al_detach_audio_stream] is automatically called on it first.

See also: [al_drain_audio_stream].

### API: al_get_audio_stream_event_source

Retrieve the associated event source.

See [al_get_audio_stream_fragment] for a description of the
ALLEGRO_EVENT_AUDIO_STREAM_FRAGMENT event that audio streams emit.

### API: al_drain_audio_stream

You should call this to finalise an audio stream that you will no longer
be feeding, to wait for all pending buffers to finish playing.
The stream's playing state will change to false.

See also: [al_destroy_audio_stream]

### API: al_rewind_audio_stream

Set the streaming file playing position to the beginning. Returns true on
success. Currently this can only be called on streams created with
[al_load_audio_stream], [al_load_audio_stream_f] and the format-specific
functions underlying those functions.

### API: al_get_audio_stream_frequency

Return the stream frequency.

### API: al_get_audio_stream_channels

Return the stream channel configuration.

See also: [ALLEGRO_CHANNEL_CONF].

### API: al_get_audio_stream_depth

Return the stream audio depth.

See also: [ALLEGRO_AUDIO_DEPTH].

### API: al_get_audio_stream_length

Return the stream length in samples.

### API: al_get_audio_stream_speed

Return the relative playback speed.

See also: [al_set_audio_stream_speed].

### API: al_set_audio_stream_speed

Set the relative playback speed.  1.0 is normal speed.

Return true on success, false on failure.  Will fail if the sample instance is
attached directly to a voice.

See also: [al_get_audio_stream_speed].

### API: al_get_audio_stream_gain

Return the playback gain.

See also: [al_set_audio_stream_gain].

### API: al_set_audio_stream_gain

Set the playback gain.

Returns true on success, false on failure.  Will fail if the sample instance
is attached directly to a voice.

See also: [al_get_audio_stream_gain].

### API: al_get_audio_stream_pan

Get the pan value.

See also: [al_set_audio_stream_pan].

### API: al_set_audio_stream_pan

Set the pan value on an audio stream.  A value of -1.0 means to play the
stream only through the left speaker; +1.0 means only through the right
speaker; 0.0 means the sample is centre balanced.
A special value [ALLEGRO_AUDIO_PAN_NONE] disables panning and plays the
stream at its original level.  This will be louder than a pan value of 0.0.

Returns true on success, false on failure.
Will fail if the sample instance is attached directly to a voice.

See also: [al_get_audio_stream_pan], [ALLEGRO_AUDIO_PAN_NONE]

### API: al_get_audio_stream_playing

Return true if the stream is playing.

See also: [al_set_audio_stream_playing].

### API: al_set_audio_stream_playing

Change whether the stream is playing.

Returns true on success, false on failure.

See also: [al_get_audio_stream_playing]

### API: al_get_audio_stream_playmode

Return the playback mode.

See also: [ALLEGRO_PLAYMODE], [al_set_audio_stream_playmode].

### API: al_set_audio_stream_playmode

Set the playback mode.

Returns true on success, false on failure.

See also: [ALLEGRO_PLAYMODE], [al_get_audio_stream_playmode].

### API: al_get_audio_stream_attached

Return whether the stream is attached to something.

See also: [al_attach_audio_stream_to_mixer], [al_attach_audio_stream_to_voice],
[al_detach_audio_stream].

### API: al_detach_audio_stream

Detach the stream from whatever it's attached to,
if anything.

See also: [al_attach_audio_stream_to_mixer], [al_attach_audio_stream_to_voice],
[al_get_audio_stream_attached].

### API: al_get_audio_stream_fragment

When using Allegro's audio streaming, you will use this function to continuously
provide new sample data to a stream.

If the stream is ready for new data, the function will return the address
of an internal buffer to be filled with audio data.
The length and format of the buffer are specified with [al_create_audio_stream]
or can be queried with the various functions described here.
Once the buffer is filled, you must signal this to Allegro by passing the
buffer to [al_set_audio_stream_fragment].

If the stream is not ready for new data, the function will return NULL.

> *Note:* If you listen to events from the stream, an
ALLEGRO_EVENT_AUDIO_STREAM_FRAGMENT event will be generated whenever a new
fragment is ready. However, getting an event is *not* a guarantee that
[al_get_audio_stream_fragment] will not return NULL, so you still must check for it.

See also: [al_set_audio_stream_fragment], [al_get_audio_stream_event_source],
[al_get_audio_stream_frequency], [al_get_audio_stream_channels],
[al_get_audio_stream_depth], [al_get_audio_stream_length]

### API: al_set_audio_stream_fragment

This function needs to be called for every successful call of
[al_get_audio_stream_fragment] to indicate that the buffer is filled with new data.

See also: [al_get_audio_stream_fragment]

### API: al_get_audio_stream_fragments

Returns the number of fragments this stream uses. This is the same value as
passed to [al_create_audio_stream] when a new stream is created.

See also: [al_get_available_audio_stream_fragments]

### API: al_get_available_audio_stream_fragments

Returns the number of available fragments in the stream, that is, fragments
which are not currently filled with data for playback.

See also: [al_get_audio_stream_fragment], [al_get_audio_stream_fragments]

### API: al_seek_audio_stream_secs

Set the streaming file playing position to time. Returns true on success.
Currently this can only be called on streams created with
[al_load_audio_stream], [al_load_audio_stream_f] and the format-specific
functions underlying those functions.

See also: [al_get_audio_stream_position_secs],
[al_get_audio_stream_length_secs]

### API: al_get_audio_stream_position_secs

Return the position of the stream in seconds.
Currently this can only be called on streams created with
[al_load_audio_stream].

See also: [al_get_audio_stream_length_secs]

### API: al_get_audio_stream_length_secs

Return the length of the stream in seconds, if known.
Otherwise returns zero.

Currently this can only be called on streams created with
[al_load_audio_stream], [al_load_audio_stream_f] and the format-specific
functions underlying those functions.

See also: [al_get_audio_stream_position_secs]

### API: al_set_audio_stream_loop_secs

Sets the loop points for the stream in seconds.
Currently this can only be called on streams created with
[al_load_audio_stream], [al_load_audio_stream_f] and the format-specific
functions underlying those functions.

## Audio file I/O

### API: al_register_sample_loader

Register a handler for [al_load_sample].  The given function will be used to
handle the loading of sample files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `loader` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_sample_loader_f], [al_register_sample_saver]

### API: al_register_sample_loader_f

Register a handler for [al_load_sample_f].  The given function will be used to
handle the loading of sample files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `loader` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_sample_loader]

### API: al_register_sample_saver

Register a handler for [al_save_sample].  The given function will be used to
handle the saving of sample files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `saver` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_sample_saver_f], [al_register_sample_loader]

### API: al_register_sample_saver_f

Register a handler for [al_save_sample_f].  The given function will be used to
handle the saving of sample files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `saver` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_sample_saver]

### API: al_register_audio_stream_loader

Register a handler for [al_load_audio_stream].  The given function will be
used to open streams from files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `stream_loader` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_audio_stream_loader_f]

### API: al_register_audio_stream_loader_f

Register a handler for [al_load_audio_stream_f].  The given function will be
used to open streams from files with the given extension.

The extension should include the leading dot ('.') character.
It will be matched case-insensitively.

The `stream_loader` argument may be NULL to unregister an entry.

Returns true on success, false on error.
Returns false if unregistering an entry that doesn't exist.

See also: [al_register_audio_stream_loader]

### API: al_load_sample

Loads a few different audio file formats based on their extension.

Note that this stores the entire file in memory at once, which
may be time consuming.  To read the file as it is needed, 
use [al_load_audio_stream].

Returns the sample on success, NULL on failure.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_register_sample_loader], [al_init_acodec_addon]

### API: al_load_sample_f

Loads an audio file from an [ALLEGRO_FILE] stream into an [ALLEGRO_SAMPLE].
The file type is determined by the passed 'ident' parameter, which is a file
name extension including the leading dot.

Note that this stores the entire file in memory at once, which
may be time consuming.  To read the file as it is needed, 
use [al_load_audio_stream_f].

Returns the sample on success, NULL on failure.
The file remains open afterwards.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_register_sample_loader_f], [al_init_acodec_addon]

### API: al_load_audio_stream

Loads an audio file from disk as it is needed.

Unlike regular streams, the one returned by this function
need not be fed by the user; the library will automatically
read more of the file as it is needed.  The stream will 
contain *buffer_count* buffers with *samples* samples.

The audio stream will start in the playing state.
It should be attached to a voice or mixer to generate any output.
See [ALLEGRO_AUDIO_STREAM] for more details.

Returns the stream on success, NULL on failure.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_load_audio_stream_f], [al_register_audio_stream_loader],
[al_init_acodec_addon]

### API: al_load_audio_stream_f

Loads an audio file from [ALLEGRO_FILE] stream as it is needed.

Unlike regular streams, the one returned by this function
need not be fed by the user; the library will automatically
read more of the file as it is needed.  The stream will 
contain *buffer_count* buffers with *samples* samples.

The file type is determined by the passed 'ident' parameter, which is a file
name extension including the leading dot.

The audio stream will start in the playing state.
It should be attached to a voice or mixer to generate any output.
See [ALLEGRO_AUDIO_STREAM] for more details.

Returns the stream on success, NULL on failure.
On success the file should be considered owned by the audio stream,
and will be closed when the audio stream is destroyed.
On failure the file will be closed.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_load_audio_stream], [al_register_audio_stream_loader_f],
[al_init_acodec_addon]

### API: al_save_sample

Writes a sample into a file.  Currently, wav is
the only supported format, and the extension
must be ".wav".

Returns true on success, false on error.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_save_sample_f], [al_register_sample_saver],
[al_init_acodec_addon]

### API: al_save_sample_f

Writes a sample into a [ALLEGRO_FILE] filestream.  Currently, wav is
the only supported format, and the extension
must be ".wav".

Returns true on success, false on error.
The file remains open afterwards.

> *Note:* the allegro_audio library does not support any audio file formats by
default.  You must use the allegro_acodec addon, or register your own format
handler.

See also: [al_save_sample], [al_register_sample_saver_f],
[al_init_acodec_addon]

