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30 * Header file for CCITT conversion routines.
36 #define AUDIO_ENCODING_ULAW (1) /* ISDN u-law */
37 #define AUDIO_ENCODING_ALAW (2) /* ISDN A-law */
38 #define AUDIO_ENCODING_LINEAR (3) /* PCM 2's-complement (0-center) */
41 * The following is the definition of the state structure
42 * used by the G.721/G.723 encoder and decoder to preserve their internal
43 * state between successive calls. The meanings of the majority
44 * of the state structure fields are explained in detail in the
45 * CCITT Recommendation G.721. The field names are essentially indentical
46 * to variable names in the bit level description of the coding algorithm
47 * included in this Recommendation.
50 long yl; /* Locked or steady state step size multiplier. */
51 short yu; /* Unlocked or non-steady state step size multiplier. */
52 short dms; /* Short term energy estimate. */
53 short dml; /* Long term energy estimate. */
54 short ap; /* Linear weighting coefficient of 'yl' and 'yu'. */
56 short a[2]; /* Coefficients of pole portion of prediction filter. */
57 short b[6]; /* Coefficients of zero portion of prediction filter. */
59 * Signs of previous two samples of a partially
60 * reconstructed signal.
63 * Previous 6 samples of the quantized difference
64 * signal represented in an internal floating point
68 * Previous 2 samples of the quantized difference
69 * signal represented in an internal floating point
72 char td; /* delayed tone detect, new in 1988 version */
75 /* External function definitions. */
77 extern void g72x_init_state(struct g72x_state *);
78 extern int g721_encoder(
81 struct g72x_state *state_ptr);
82 extern int g721_decoder(
85 struct g72x_state *state_ptr);
86 extern int g723_24_encoder(
89 struct g72x_state *state_ptr);
90 extern int g723_24_decoder(
93 struct g72x_state *state_ptr);
94 extern int g723_40_encoder(
97 struct g72x_state *state_ptr);
98 extern int g723_40_decoder(
101 struct g72x_state *state_ptr);
110 extern int reconstruct(int,int,int);void
120 struct g72x_state *state_ptr);
145 unsigned char a_val);
148 linear2ulaw(int pcm_val);
150 extern int ulaw2linear( unsigned char u_val);
152 extern int predictor_zero(struct g72x_state *state_ptr);
154 extern int predictor_pole( struct g72x_state *state_ptr);
155 extern int step_size( struct g72x_state *state_ptr);
156 #endif /* !_G72X_H */