g72x.h

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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);
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);


extern int
quantize(
         int            d,
         int            y,
        short           *table,
        int             size);
extern int reconstruct(int,int,int);void

extern update(
        int             code_size,
        int             y,
        int             wi,
        int             fi,
        int             dq,
        int             sr,
        int             dqsez,
        struct g72x_state *state_ptr);
extern int
tandem_adjust_alaw(
        int             sr,
        int             se,
        int             y,
        int             i,
        int             sign,
        short           *qtab);

extern int
tandem_adjust_ulaw(
        int             sr,
        int             se,
        int             y,
        int             i,
        int             sign,
        short           *qtab);

extern unsigned char
linear2alaw(
        int             pcm_val);

extern int
alaw2linear(
        unsigned char   a_val);

extern unsigned char
linear2ulaw(int         pcm_val);

extern int ulaw2linear( unsigned char   u_val);

extern int predictor_zero(struct g72x_state *state_ptr);

extern int predictor_pole(      struct g72x_state *state_ptr);
extern int step_size(   struct g72x_state *state_ptr);
#endif /* !_G72X_H */