Channels

Mixer channels 0 to 23 that play sounds. More...

Functions
int	audio_channel_play_sound (int channel, audio_sound_t sound)
int	audio_play_sound (audio_sound_t sound)
int	audio_channel_stop (int channel)
int	audio_channel_is_playing (int channel)
int	audio_channel_get_playing_sound (int channel, audio_sound_t *sound_out)
int	audio_channel_set_volume (int channel, int volume_percent)
int	audio_channel_set_volume_and_pan (int channel, int volume_percent, int pan)
int	audio_channel_set_pitch (int channel, float ratio)

Detailed Description

Mixer channels 0 to 23 that play sounds.

A channel keeps its volume, pan and pitch until they are changed, including across sounds and before the first sound plays. Commands that return AUDIO_OK without a reply from the driver (play, stop and the volume, pan and pitch setters) are validated by the library, sent, and executed by the driver in the order they were sent; a later call such as audio_channel_is_playing() sees their effect.

Function Documentation

audio_channel_get_playing_sound()

int audio_channel_get_playing_sound	(	int	channel,
		audio_sound_t *	sound_out )

The sound playing on a channel.

Parameters

	channel	0 to 23.
[out]	sound_out	Receives the handle, or AUDIO_SOUND_INVALID when the channel is idle.

Returns

AUDIO_OK or a negative error.

audio_channel_is_playing()

int audio_channel_is_playing

(

int

channel

)

Whether a channel is playing. A sound that finished counts as not playing.

Parameters

channel

0 to 23.

Returns

1 playing, 0 idle, or a negative error.

audio_channel_play_sound()

int audio_channel_play_sound	(	int	channel,
		audio_sound_t	sound )

Plays a sound on a channel, replacing whatever was playing there. The channel keeps its volume, pan and pitch.

Parameters

channel	0 to 23.
sound	A handle from a load function.

Returns

AUDIO_OK, or -AUDIO_ERR_INVALID_ARGUMENT for a channel out of range or a handle that is not live.

audio_channel_set_pitch()

int audio_channel_set_pitch	(	int	channel,
		float	ratio )

Sets the playback speed as a ratio of the sound's own rate. Applies at once to a playing sound and persists.

Parameters

channel	0 to 23.
ratio	0.0625 to 4.0; 1.0 plays at the sound's rate.

Returns

AUDIO_OK or -AUDIO_ERR_INVALID_ARGUMENT.

audio_channel_set_volume()

int audio_channel_set_volume	(	int	channel,
		int	volume_percent )

Sets the channel volume and leaves pan and pitch unchanged. Applies at once to a playing sound and persists.

Parameters

channel	0 to 23.
volume_percent	0 to 100.

Returns

AUDIO_OK or -AUDIO_ERR_INVALID_ARGUMENT.

audio_channel_set_volume_and_pan()

int audio_channel_set_volume_and_pan	(	int	channel,
		int	volume_percent,
		int	pan )

Sets volume and pan together. Applies at once to a playing sound and persists.

Parameters

channel	0 to 23.
volume_percent	0 to 100.
pan	-100 (left) to 100 (right), 0 centered; it works as a balance for stereo sounds.

Returns

AUDIO_OK or -AUDIO_ERR_INVALID_ARGUMENT.

audio_channel_stop()

int audio_channel_stop

(

int

channel

)

Stops the sound on a channel. Volume, pan and pitch are kept.

Parameters

channel

0 to 23.

Returns

AUDIO_OK, also for an idle channel, or -AUDIO_ERR_INVALID_ARGUMENT.

audio_play_sound()

int audio_play_sound

(

audio_sound_t

sound

)

Plays a sound on the first idle channel, searching from channel 0. The channel is reset to volume 100, centered, normal pitch before the sound starts.

Parameters

sound

A handle from a load function.

Returns

The channel number 0-23, -AUDIO_ERR_NO_FREE_CHANNEL (nothing is interrupted), -AUDIO_ERR_INVALID_ARGUMENT or -AUDIO_ERR_NOT_INITIALIZED.

Note

Waits for the driver's answer, since the channel number is the result.