ado_mixer_element_accu3()

Create an accumulator (type 3) element

Synopsis:

#include <audio_driver.h>

ado_mixer_delement_t *
   ado_mixer_element_accu3 (
      ado_mixer_t *mixer,
      char *name,
      uint32_t number_of_voices,
      struct snd_mixer_element_accu3_range *ranges,
      ado_mixer_delement_control_accu3_t *control,
      void *instance_data,
      void (*instance_free) (void *data) );

Arguments:

mixer

A pointer to the ado_mixer_t structure that specifies the mixer to create the element in. This structure was created by ado_mixer_create().

name

The name of the element. Elements are referred to by name, so be careful; for some standard names, see <asound.h>.

attenuation

The amount of attenuation the element contributes to the stream passing through it; usually 0 dB.

number_of_voices

The number of voices in each channel that the element accumulates.

ranges

The range of the attenuation control for the type-3 accumulator.

control

A callback function, of type ado_mixer_delement_control_accu3_t, that determines the attenuation.

The prototype is:

int32_t control(
           MIXER_CONTEXT_T *context,
           ado_mixer_delement_t *element,
           uint8_t set,
           uint32_t *voices,
           void *instance_data );
  

instance_data

A pointer to any instance data that you need to pass to the control callback. This can be a pointer to allocated memory, in which case you'll need to define the instance_free function.

If you need to access this instance data, you have to call ado_mixer_get_element_instance_data() because ado_mixer_delement_t is an opaque data type.

instance_free

A function that must free any allocated instance data. It's called when the element is destroyed.

Description:

The ado_mixer_element_accu3() convenience function automates the creation of an accumulator (type 3) element. An accumulator of type 3 mixes together multiple inputs into a single output with programmable attenuation.

Returns:

A pointer to the newly allocated accumulator (type 3) element.

Classification:

QNX Neutrino

See also:

ado_mixer_create(), ado_mixer_element_accu1(), ado_mixer_element_accu2(), ado_mixer_get_element_instance_data()