www.pudn.com > G711-729.rar > g72x.h

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 * for unrestricted use.  Users may copy or modify this source code without 
 * charge. 
 * 
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 * Sun source code is provided with no support and without any obligation on 
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 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 
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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_stat(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); 
extern int g723_24_encoder( 
		int sample, 
		int in_coding, 
		struct g72x_state *state_ptr); 
extern int g723_24_decoder( 
		int code, 
		int out_coding, 
		struct g72x_state *state_ptr); 
extern int g723_40_encoder( 
		int sample, 
		int in_coding, 
		struct g72x_state *state_ptr); 
extern int g723_40_decoder( 
		int code, 
		int out_coding, 
		struct g72x_state *state_ptr); 
 
#endif /* !_G72X_H */