www.pudn.com > VOIP(H323).rar > g72x.h
/* $Id: g72x.h,v 1.1 2004/04/26 14:57:43 martinm Exp $
$Log: g72x.h,v $
Revision 1.1 2004/04/26 14:57:43 martinm
Initial revision
*/
/*
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* for unrestricted use. Users may copy or modify this source code without
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*/
/*
* g72x.h
*
* Header file for CCITT conversion routines.
*
*/
#ifndef _G72X_H
#define _G72X_H
#define AUDIO_ENCODING_ULAW (1) /* ISDN u-law */
#define AUDIO_ENCODING_ALAW (2) /* ISDN A-law */
#define AUDIO_ENCODING_LINEAR (3) /* PCM 2's-complement (0-center) */
/*
* The following is the definition of the state structure
* used by the G.721/G.723 encoder and decoder to preserve their internal
* state between successive calls. The meanings of the majority
* of the state structure fields are explained in detail in the
* CCITT Recommendation G.721. The field names are essentially indentical
* to variable names in the bit level description of the coding algorithm
* included in this Recommendation.
*/
struct g72x_state {
long yl; /* Locked or steady state step size multiplier. */
short yu; /* Unlocked or non-steady state step size multiplier. */
short dms; /* Short term energy estimate. */
short dml; /* Long term energy estimate. */
short ap; /* Linear weighting coefficient of 'yl' and 'yu'. */
short a[2]; /* Coefficients of pole portion of prediction filter. */
short b[6]; /* Coefficients of zero portion of prediction filter. */
short pk[2]; /*
* Signs of previous two samples of a partially
* reconstructed signal.
*/
short dq[6]; /*
* Previous 6 samples of the quantized difference
* signal represented in an internal floating point
* format.
*/
short sr[2]; /*
* Previous 2 samples of the quantized difference
* signal represented in an internal floating point
* format.
*/
char td; /* delayed tone detect, new in 1988 version */
};
/* External function definitions. */
extern void g72x_init_state(struct g72x_state *);
extern int g721_encoder(int sample, int in_coding, struct g72x_state *state_ptr);
extern int g721_decoder(int code, int out_coding, struct g72x_state *state_ptr);
int g723_24_encoder(int sample, int in_coding, struct g72x_state *state_ptr);
int g723_24_decoder(int code, int out_coding, struct g72x_state *state_ptr);
int g723_40_encoder(int sample, int in_coding, struct g72x_state *state_ptr);
int g723_40_decoder(int code, int out_coding, struct g72x_state *state_ptr);
int tandem_adjust_ulaw(int sr, int se, int y, int i, int sign, short *qtab);
int ulaw2linear(unsigned char u_val);
int alaw2linear(unsigned char a_val);
int predictor_zero(struct g72x_state *state_ptr);
int predictor_pole(struct g72x_state *state_ptr);
int step_size(struct g72x_state *state_ptr);
int quantize(int d, int y, short *table, int size);
int reconstruct(int sign, int dqln, int y);
void update(int code_size, int y, int wi, int fi, int dq, int sr, int dqsez, struct g72x_state *state_ptr);
int tandem_adjust_alaw(int sr, int se, int y, int i, int sign, short *qtab);
//unsigned char linear2alaw(int pcm_val);
//unsigned char linear2ulaw(int pcm_val);
extern int pack_output(unsigned code, int bits, unsigned char *pDataTrack);
#endif /* !_G72X_H */