Loads a sample from a file, supporting both mono and stereo WAV and mono
VOC files, in 8 or 16-bit formats, as well as formats handled by functions
registered using register_sample_file_type(). Example:
SAMPLE *sample = load_sample(user_input);
if (!sample)
abort_on_error("Couldn't load sample!");
Return value:
Returns a pointer to the SAMPLE or NULL on error. Remember to free this
sample later to avoid memory leaks.
See also:
destroy_sample,
load_voc,
load_wav,
play_sample,
save_sample,
register_sample_file_type,
Voice control.
Examples using this:
exsample.
Loads a sample from a RIFF WAV file. Example:
SAMPLE *sample = load_wav("scream.wav");
if (!sample)
abort_on_error("Couldn't scare user!");
Return value:
Returns a pointer to the SAMPLE or NULL on error. Remember to free this
sample later to avoid memory leaks.
See also:
load_sample,
register_sample_file_type.
A version of load_wav() which reads from a packfile. Example:
PACKFILE *packfile;
SAMPLE *sample;
packfile = pack_fopen("sound.wav", F_READ);
if (!packfile)
abort_on_error("Couldn't open sound.wav");
sample = load_wav_pf(packfile);
if (!sample)
abort_on_error("Error loading sound.wav");
Return value:
Returns a pointer to the SAMPLE or NULL on error. Remember to free this
sample later to avoid memory leaks.
See also:
load_wav.
Loads a sample from a Creative Labs VOC file. Example:
SAMPLE *sample = load_voc("alarm.voc");
if (!sample)
abort_on_error("Couldn't alert user!");
Return value:
Returns a pointer to the SAMPLE or NULL on error. Remember to free this
sample later to avoid memory leaks.
See also:
load_sample,
register_sample_file_type.
A version of load_voc() which reads from a packfile. Example:
PACKFILE *packfile;
SAMPLE *sample;
packfile = pack_fopen("sound.wav", F_READ);
if (!packfile)
abort_on_error("Couldn't open sound.wav");
sample = load_wav_pf(packfile);
if (!sample)
abort_on_error("Error loading sound.wav");
Return value:
Returns a pointer to the SAMPLE or NULL on error. Remember to free this
sample later to avoid memory leaks.
See also:
load_voc.
Writes a sample into a file. The output format is determined from the
filename extension. At present Allegro does not natively support the
writing of any sample formats, so you must register a custom saver routine
with register_sample_file_type(). Example:
if (save_sample("sound.wav", sample) != 0)
abort_on_error("Couldn't save sample!");
Return value:
Returns zero on success, non-zero otherwise.
See also:
load_sample,
register_sample_file_type.
Constructs a new sample structure of the specified type. Read chapter
"Structures and types defined by Allegro" for an internal description of
the SAMPLE structure. The `bits' parameter can be 8 or 16, `stereo' can be
zero for mono samples and non-zero for stereo samples, `freq' is the
frequency in hertz, and `len' is the number of samples you want to allocate
for the full sound buffer.
Return value:
Returns a pointer to the created sample, or NULL if the sample could not
be created. Remember to free this sample later to avoid memory leaks.
See also:
load_sample,
destroy_sample,
Structures and types defined by Allegro.
Destroys a sample structure when you are done with it. It is safe to call
this even when the sample might be playing, because it checks and will
kill it off if it is active. Use this to avoid memory leaks in your
program.
See also:
load_sample.
Examples using this:
exsample.
Under DOS, locks all the memory used by a sample. You don't normally need
to call this function because load_sample() and create_sample() do it for
you.
See also:
load_sample,
create_sample.
Informs the load_sample() function of a new sample file type,
providing routines to read and write samples in this format (either
function may be NULL). Example:
SAMPLE *load_mp3(const char *filename)
{
...
}
register_sample_file_type("mp3", load_mp3, NULL);
See also:
load_sample,
save_sample.
Triggers a sample at the specified volume, pan position, and frequency.
The parameters `vol' and `pan' range from 0 (min/left) to 255 (max/right).
Frequency is relative rather than absolute: 1000 represents the frequency
that the sample was recorded at, 2000 is twice this, etc. If `loop' is not
zero, the sample will repeat until you call stop_sample(), and can be
manipulated while it is playing by calling adjust_sample(). Example:
/* Scream from the left speaker, twice the freq. */
int sound = play_sample(scream, 255, 0, 2000, 0);
Return value:
Returns the voice number that was allocated for the sample or negative if
no voices were available.
See also:
install_sound,
load_sample,
adjust_sample,
stop_sample,
Voice control.
Examples using this:
exsample,
exsprite.
Alters the parameters of a sample while it is playing (useful for
manipulating looped sounds). You can alter the volume, pan, and frequency,
and can also clear the loop flag, which will stop the sample when it next
reaches the end of its loop. The values of the parameters are just like
those of play_sample(). If there are several copies of the same sample
playing, this will adjust the first one it comes across. If the sample is
not playing it has no effect.
See also:
play_sample.
Examples using this:
exsample.
Stop a sample from playing, which is required if you have set a sample
going in looped mode. If there are several copies of the sample playing,
it will stop them all. You must still destroy the sample using
destroy_sample().
See also:
play_sample,
destroy_sample.
If you need more detailed control over how samples are played, you can use
the lower level voice functions rather than just calling play_sample(). This
is rather more work, because you have to explicitly allocate and free the
voices rather than them being automatically released when they finish
playing, but allows far more precise specification of exactly how you want
everything to sound. You may also want to modify a couple of fields from the
SAMPLE structure. Read chapter "Structures and types defined by Allegro" for
its definition.
See also:
install_sound,
allocate_voice,
deallocate_voice,
reallocate_voice,
release_voice,
voice_start,
voice_set_priority,
voice_check,
voice_set_position,
voice_set_playmode,
voice_set_volume,
voice_set_frequency,
voice_set_pan,
SAMPLE.
Allocates a sound card voice and prepares it for playing the specified
sample, setting up sensible default parameters (maximum volume, centre
pan, no change of pitch, no looping). When you are finished with the
voice you must free it by calling deallocate_voice() or release_voice().
Allegro can manage up to 256 simultaneous voices, but that limit may be
lower due to hardware reasons.
Return value:
Returns the voice number, or -1 if no voices are available.
See also:
Voice control,
deallocate_voice,
reallocate_voice,
release_voice,
load_sample.
Frees a sound card voice, stopping it from playing and releasing whatever
resources it is using.
See also:
allocate_voice,
voice_stop.
Switches an already-allocated voice to use a different sample. Calling
reallocate_voice(voice, sample) is equivalent to:
deallocate_voice(voice);
voice = allocate_voice(sample);
See also:
allocate_voice,
deallocate_voice,
load_sample.
Releases a sound card voice, indicating that you are no longer interested
in manipulating it. The sound will continue to play, and any resources
that it is using will automatically be freed when it finishes. This is
essentially the same as deallocate_voice(), but it waits for the sound to
stop playing before taking effect.
See also:
allocate_voice,
deallocate_voice.
Activates a voice, using whatever parameters have been set for it.
See also:
Voice control,
allocate_voice,
voice_stop,
release_voice.
Examples using this:
exstream.
Stops a voice, storing the current position and state so that it may
later be resumed by calling voice_start().
See also:
voice_start,
deallocate_voice,
release_voice.
Examples using this:
exstream.
Sets the priority of a voice (range 0-255). This is used to decide which
voices should be chopped off, if you attempt to play more than the
sound card driver can handle.
See also:
Voice control.
Checks whether a voice is currently allocated.
Return value:
Returns a pointer to the sample that the voice is using, or NULL if the
voice is inactive (ie. it has been deallocated, or the release_voice()
function has been called and the sample has then finished playing).
See also:
allocate_voice,
voice_start,
voice_get_position.
Returns the current position of a voice, in sample units, or -1 if it has
finished playing.
See also:
Voice control,
voice_set_position.
Sets the position of a voice, in sample units.
See also:
Voice control,
voice_get_position,
voice_set_playmode.
Adjusts the loop status of the specified voice. This can be done while
the voice is playing, so you can start a sample in looped mode (having
set the loop start and end positions to the appropriate values), and then
clear the loop flag when you want to end the sound, which will cause it
to continue past the loop end, play the subsequent part of the sample,
and finish in the normal way. The mode parameter is a bitfield containing
the following values:
-
PLAYMODE_PLAY
Plays the sample a single time. This is the default if you don't set
the loop flag.
-
PLAYMODE_LOOP
Loops repeatedly through the sample, jumping back to the loop start
position upon reaching the loop end.
-
PLAYMODE_FORWARD
Plays the sample from beginning to end. This is the default if you
don't set the backward flag.
-
PLAYMODE_BACKWARD
Reverses the direction of the sample. If you combine this with the
loop flag, the sample jumps to the loop end position upon reaching the
loop start (ie. you do not need to reverse the loop start and end
values when you play the sample in reverse).
-
PLAYMODE_BIDIR
When used in combination with the loop flag, causes the sample to
change direction each time it reaches one of the loop points, so it
alternates between playing forwards and in reverse.
See also:
Voice control.
Returns the current volume of the voice, range 0-255. Otherwise it
returns -1 if that cannot be determined (because it has finished or
been preempted by a different sound).
See also:
Voice control,
voice_set_volume.
Sets the volume of the voice, range 0-255.
See also:
Voice control,
voice_get_volume,
voice_ramp_volume.
Starts a volume ramp (crescendo or diminuendo) from the current volume to
the specified ending volume, lasting for time milliseconds. The volume is
a value in the range 0-255.
See also:
Voice control,
voice_set_volume.
Interrupts a volume ramp operation.
See also:
voice_ramp_volume.
Returns the current pitch of the voice, in Hz.
See also:
Voice control,
voice_set_frequency.
Sets the pitch of the voice, in Hz.
See also:
Voice control,
voice_get_frequency,
voice_sweep_frequency.
Starts a frequency sweep (glissando) from the current pitch to the
specified ending pitch, lasting for time milliseconds.
See also:
Voice control,
voice_set_frequency.
Interrupts a frequency sweep operation.
See also:
voice_sweep_frequency.
Returns the current pan position, from 0 (left) to 255 (right).
See also:
Voice control,
voice_set_pan.
Sets the pan position, ranging from 0 (left) to 255 (right).
See also:
Voice control,
voice_get_pan,
voice_sweep_pan.
Starts a pan sweep (left <-> right movement) from the current position to
the specified ending position, lasting for time milliseconds.
See also:
Voice control,
voice_set_pan.
Interrupts a pan sweep operation.
See also:
voice_sweep_pan.
Sets the echo parameters for a voice (not currently implemented).
See also:
Voice control.
Sets the tremolo parameters for a voice (not currently implemented).
See also:
Voice control.
Sets the vibrato parameters for a voice (not currently implemented).
See also:
Voice control.