High Level API Functions

Functions
void	ic_init (ic_state_t *state)
	Initialise IC data structures and set parameters according to ic_defines.h. More...
void	ic_filter (ic_state_t *state, int32_t y_data[IC_FRAME_ADVANCE], int32_t x_data[IC_FRAME_ADVANCE], int32_t output[IC_FRAME_ADVANCE])
	Filter one frame of audio data inside the IC. More...
void	ic_adapt (ic_state_t *state, uint8_t vad, int32_t output[IC_FRAME_ADVANCE])
	Adapts the IC filter according to previous frame's statistics and VAD input. More...

Detailed Description

Function Documentation

ic_adapt()

void ic_adapt	(	ic_state_t *	state,
		uint8_t	vad,
		int32_t	output[IC_FRAME_ADVANCE]
	)

Adapts the IC filter according to previous frame's statistics and VAD input.

This function should be called after each call to ic_filter. Filter and adapt functions are seprated so that the external VAD function can operate on that frame's filtered samples.

Parameters

[in,out]	state	pointer to IC state structure
[in]	vad	VAD probability between 0 (0% VAD probability) and 255 (100% VAD probability)
[in]	output	array reference to previously filtered output samples

ic_filter()

void ic_filter	(	ic_state_t *	state,
		int32_t	y_data[IC_FRAME_ADVANCE],
		int32_t	x_data[IC_FRAME_ADVANCE],
		int32_t	output[IC_FRAME_ADVANCE]
	)

Filter one frame of audio data inside the IC.

This should be called once per new frame of IC_FRAME_ADVANCE samples. The y_data array contains the microphone data that is to have the noise subtracted from it and x_data is the noise reference source which is internally delayed before being fed into the adaptive filter. Note that the y_data input array is internally delayed by the call to ic_filter() and so contains the delayed y_data afterwards. Typically it does not matter which mic channel is connected to x or y_data as long as the separation is appropriate. The performance of this filter has been optimised for a 71mm mic separation distance.

Parameters

[in,out]	state	pointer to IC state structure
[in,out]	y_data	array reference of mic 0 input buffer. Modified during call
[in]	x_data	array reference of mic 1 input buffer
[out]	output	array reference containing IC processed output buffer

ic_init()

void ic_init

(

ic_state_t *

state

)

Initialise IC data structures and set parameters according to ic_defines.h.

This is the first function that must called after creating an ic_state_t instance.

Parameters

[in,out]

state

pointer to IC state structure