agc.h File Reference

routine that implements automatic gain control More...

#include <sphinxbase/sphinxbase_export.h>
#include <sphinxbase/prim_type.h>
#include <sphinxbase/fe.h>

Go to the source code of this file.

Data Structures
struct	agc_s
	Structure holding data for doing AGC. More...

Typedefs
typedef enum agc_type_e	agc_type_t
	Types of acoustic gain control to apply to the features.
typedef struct agc_s	agc_t
	Structure holding data for doing AGC.

Enumerations
enum	agc_type_e { AGC_NONE = 0, AGC_MAX, AGC_EMAX, AGC_NOISE }
	Types of acoustic gain control to apply to the features.

Functions
SPHINXBASE_EXPORT agc_type_t	agc_type_from_str (const char *str)
	Convert string representation (from command-line) to agc_type_t.
SPHINXBASE_EXPORT agc_t *	agc_init (void)
	Initialize AGC structure with default values.
SPHINXBASE_EXPORT void	agc_free (agc_t *agc)
	Free AGC structure.
SPHINXBASE_EXPORT void	agc_max (agc_t *agc, mfcc_t **mfc, int32 n_frame)
	Apply AGC to the given mfc vectors (normalize all C0 mfc coefficients in the given input such that the max C0 value is 0, by subtracting the input max C0 from all). More...
SPHINXBASE_EXPORT void	agc_emax (agc_t *agc, mfcc_t **mfc, int32 n_frame)
	Apply AGC to the given block of MFC vectors. More...
SPHINXBASE_EXPORT void	agc_emax_update (agc_t *agc)
	Update AGC parameters for next utterance. More...
SPHINXBASE_EXPORT float32	agc_emax_get (agc_t *agc)
	Get the current AGC maximum estimate.
SPHINXBASE_EXPORT void	agc_emax_set (agc_t *agc, float32 m)
	Set the current AGC maximum estimate.
SPHINXBASE_EXPORT void	agc_noise (agc_t *agc, mfcc_t **mfc, int32 n_frame)
	Apply AGC using noise threshold to the given block of MFC vectors. More...
SPHINXBASE_EXPORT float32	agc_get_threshold (agc_t *agc)
	Get the current AGC noise threshold.
SPHINXBASE_EXPORT void	agc_set_threshold (agc_t *agc, float32 threshold)
	Set the current AGC noise threshold.

Variables
SPHINXBASE_EXPORT const char *	agc_type_str []
	String representations of agc_type_t values. More...

Detailed Description

routine that implements automatic gain control

Warning

This function may not be fully compatible with SphinxTrain's family of AGC.

This implements AGC.

Definition in file agc.h.

Function Documentation

SPHINXBASE_EXPORT void agc_emax	(	agc_t *	agc,
		mfcc_t **	mfc,
		int32	n_frame
	)

Apply AGC to the given block of MFC vectors.

Unlike agc_max() this does not require the entire utterance to be available. Call agc_emax_update() at the end of each utterance to update the AGC parameters.

Parameters

agc	In: AGC structure
mfc	In/Out: mfc[f] = cepstrum vector in frame f
n_frame	In: number of frames of cepstrum vectors supplied

Definition at line 142 of file agc.c.

References agc_s::max, agc_s::obs_frame, and agc_s::obs_max.

SPHINXBASE_EXPORT void agc_emax_update

(

agc_t *

agc

)

Update AGC parameters for next utterance.

Parameters

agc	In: AGC structure

Definition at line 159 of file agc.c.

References E_INFO, agc_s::max, agc_s::obs_frame, agc_s::obs_max, and agc_s::obs_utt.

Referenced by feat_update_stats().

SPHINXBASE_EXPORT void agc_max	(	agc_t *	agc,
		mfcc_t **	mfc,
		int32	n_frame
	)

Apply AGC to the given mfc vectors (normalize all C0 mfc coefficients in the given input such that the max C0 value is 0, by subtracting the input max C0 from all).

This function operates on an entire utterance at a time. Hence, the entire utterance must be available beforehand (batchmode).

Apply AGC to the given mfc vectors (normalize all C0 mfc coefficients in the given input such that the max C0 value is 0, by subtracting the input max C0 from all).

Parameters

agc	In: AGC structure (not used)
mfc	In/Out: mfc[f] = cepstrum vector in frame f
n_frame	In: number of frames of cepstrum vectors supplied

Definition at line 109 of file agc.c.

References E_INFO, agc_s::obs_frame, and agc_s::obs_max.

SPHINXBASE_EXPORT void agc_noise	(	agc_t *	agc,
		mfcc_t **	mfc,
		int32	n_frame
	)

Apply AGC using noise threshold to the given block of MFC vectors.

Parameters

agc	In: AGC structure
mfc	In/Out: mfc[f] = cepstrum vector in frame f
n_frame	In: number of frames of cepstrum vectors supplied

Definition at line 180 of file agc.c.

References E_INFO, and agc_s::noise_thresh.

Variable Documentation

SPHINXBASE_EXPORT const char* agc_type_str[]

String representations of agc_type_t values.

Definition at line 70 of file agc.c.

Referenced by agc_type_from_str(), and feat_init().