Audio level controls

Macros
#define	DEFAULT_LINE_OUT_LEVEL   0.0
#define	DEFAULT_PGA_GAIN   16
#define	DEFAULT_HP_LEVEL   -6.0

Functions
int	Bela_setLineOutLevel (int channel, float decibel)
	Set the level of the audio line out. More...
int	Bela_setDacLevel (int channel, float decibels)
	Set the level of the audio DAC. More...
int	Bela_setDACLevel (float decibels)
int	Bela_setAdcLevel (int channel, float decibels)
	Set the level of the audio ADC. More...
int	Bela_setADCLevel (float decibels)
int	Bela_setAudioInputGain (int channel, float decibels)
	Set the gain of the audio input preamplifier. More...
int	Bela_setPgaGain (float decibels, int channel)
int	Bela_setHpLevel (int channel, float decibels)
	Set the level of the onboard headphone amplifier. More...
int	Bela_setHeadphoneLevel (float decibels)
int	Bela_muteSpeakers (int mute)
	Mute or unmute the onboard speaker amplifiers. More...

Detailed Description

These functions control the input and output levels for the audio codec. If a Bela program does not call these functions, sensible default levels will be used.

Macro Definition Documentation

#define DEFAULT_LINE_OUT_LEVEL   0.0

Default level of the line out in decibels. See Bela_setLineOutLevel().

#define DEFAULT_PGA_GAIN   16

Default level of the Programmable Gain Amplifier in decibels.

#define DEFAULT_HP_LEVEL   -6.0

Default level of the headphone output in decibels. See Bela_setHeadphoneLevel().

Function Documentation

int Bela_setLineOutLevel	(	int	channel,
		float	decibel
	)

Set the level of the audio line out.

Important: do not call this function from within render(), as it does not make any guarantees on real-time performance.

Parameters

channel	The channel to set. Use a negative value to set all channels.
decibels	Level of the line output. Valid values will depend on the codec in use.

Returns

0 on success, or nonzero if an error occurred.

int Bela_setDacLevel	(	int	channel,
		float	decibels
	)

Set the level of the audio DAC.

DEPRECATED.

Use Bela_setLineOutLevel() instead.

int Bela_setDACLevel

(

float

decibels

)

DEPRECATED.

Equivalent to Bela_setDacLevel(-1, decibels).

int Bela_setAdcLevel	(	int	channel,
		float	decibels
	)

Set the level of the audio ADC.

This function sets the level of the audio input. It does not affect the level of the (non-audio) analog inputs.

Important: do not call this function from within render(), as it does not make any guarantees on real-time performance.

Parameters

channel	The channel to set. Use a negative value to set all channels.
decibels	Level of the ADC input. Valid levels range from -12 (lowest) to 0 (highest) in steps of 1.5dB. Levels between increments of 1.5 will be rounded down.

Returns

0 on success, or nonzero if an error occurred.

int Bela_setADCLevel

(

float

decibels

)

DEPRECATED.

Equivalent to Bela_setAdcLevel(-1, decibels).

int Bela_setAudioInputGain	(	int	channel,
		float	decibels
	)

Set the gain of the audio input preamplifier.

This function sets the level of the Programmable Gain Amplifier(PGA), which amplifies the signal before the ADC.

Important: do not call this function from within render(), as it does not make any guarantees on real-time performance.

Parameters

channel	The channel to set. Use a negative value to set all channels.
decibels	Level of the PGA Valid levels range from 0 (lowest) to 59.5 (highest) in steps of 0.5dB. Levels between increments of 0.5 will be rounded. channel 1 is right

Returns

0 on success, or nonzero if an error occurred.

int Bela_setPgaGain	(	float	decibels,
		int	channel
	)

DEPRECATED.

Equivalent to Bela_setAudioInputGain(channel, decibels).

int Bela_setHpLevel	(	int	channel,
		float	decibels
	)

Set the level of the onboard headphone amplifier.

This function sets the level of the headphone output only (3-pin connector on the Bela cape or the output jack on the BeagleBone Audio Cape). It does not affect the level of the speakers or the line out pads on the cape.

Important: do not call this function from within render(), as it does not make any guarantees on real-time performance.

Parameters

channel	The channel to set. Use a negative value to set all channels.
decibels	Level of the headphone output. Valid levels range from -63.5 (lowest) to 0 (highest) in steps of 0.5dB. Levels between increments of 0.5 will be rounded down.

Returns

0 on success, or nonzero if an error occurred.

int Bela_setHeadphoneLevel

(

float

decibels

)

DEPRECATED Equivalent to Bela_setHpLevel(-1, decibels);

int Bela_muteSpeakers

(

int

mute

)

Mute or unmute the onboard speaker amplifiers.

This function mutes or unmutes the amplifiers on the Bela cape. Whether the speakers begin muted or unmuted depends on the BelaInitSettings structure passed to Bela_initAudio().

Important: do not call this function from within render(), as it does not make any guarantees on real-time performance.

Parameters

mute	0 to enable the speakers, nonzero to mute the speakers.

Returns

0 on success, or nonzero if an error occurred.