src/g72x.h

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  25
  26 /*
  27  * g72x.h
  28  *
  29  * Header file for CCITT conversion routines.
  30  *
  31  */
  32 #ifndef _G72X_H
  33 #define _G72X_H
  34
  35 /* aliases */
  36 #define g721_decoder lsx_g721_decoder
  37 #define g721_encoder lsx_g721_encoder
  38 #define g723_24_decoder lsx_g723_24_decoder
  39 #define g723_24_encoder lsx_g723_24_encoder
  40 #define g723_40_decoder lsx_g723_40_decoder
  41 #define g723_40_encoder lsx_g723_40_encoder
  42 #define g72x_init_state lsx_g72x_init_state
  43 #define predictor_pole lsx_g72x_predictor_pole
  44 #define predictor_zero lsx_g72x_predictor_zero
  45 #define quantize lsx_g72x_quantize
  46 #define reconstruct lsx_g72x_reconstruct
  47 #define step_size lsx_g72x_step_size
  48 #define tandem_adjust_alaw lsx_g72x_tandem_adjust_alaw
  49 #define tandem_adjust_ulaw lsx_g72x_tandem_adjust_ulaw
  50 #define update lsx_g72x_update
  51
  52 #define AUDIO_ENCODING_ULAW     (1)     /* ISDN u-law */
  53 #define AUDIO_ENCODING_ALAW     (2)     /* ISDN A-law */
  54 #define AUDIO_ENCODING_LINEAR   (3)     /* PCM 2's-complement (0-center) */
  55
  56 /*
  57  * The following is the definition of the state structure
  58  * used by the G.721/G.723 encoder and decoder to preserve their internal
  59  * state between successive calls.  The meanings of the majority
  60  * of the state structure fields are explained in detail in the
  61  * CCITT Recommendation G.721.  The field names are essentially indentical
  62  * to variable names in the bit level description of the coding algorithm
  63  * included in this Recommendation.
  64  */
  65 struct g72x_state {
  66         long yl;        /* Locked or steady state step size multiplier. */
  67         short yu;       /* Unlocked or non-steady state step size multiplier. */
  68         short dms;      /* Short term energy estimate. */
  69         short dml;      /* Long term energy estimate. */
  70         short ap;       /* Linear weighting coefficient of 'yl' and 'yu'. */
  71
  72         short a[2];     /* Coefficients of pole portion of prediction filter. */
  73         short b[6];     /* Coefficients of zero portion of prediction filter. */
  74         short pk[2];    /*
  75                          * Signs of previous two samples of a partially
  76                          * reconstructed signal.
  77                          */
  78         short dq[6];    /*
  79                          * Previous 6 samples of the quantized difference
  80                          * signal represented in an internal floating point
  81                          * format.
  82                          */
  83         short sr[2];    /*
  84                          * Previous 2 samples of the quantized difference
  85                          * signal represented in an internal floating point
  86                          * format.
  87                          */
  88         char td;        /* delayed tone detect, new in 1988 version */
  89 };
  90
  91 /* External function definitions. */
  92
  93 extern void g72x_init_state(struct g72x_state *);
  94 extern int g721_encoder(
  95         int sample,
  96         int in_coding,
  97         struct g72x_state *state_ptr);
  98 extern int g721_decoder(
  99         int code,
 100         int out_coding,
 101         struct g72x_state *state_ptr);
 102 extern int g723_16_encoder(
 103         int sample,
 104         int in_coding,
 105         struct g72x_state *state_ptr);
 106 extern int g723_16_decoder(
 107         int code,
 108         int out_coding,
 109         struct g72x_state *state_ptr);
 110 extern int g723_24_encoder(
 111         int sample,
 112         int in_coding,
 113         struct g72x_state *state_ptr);
 114 extern int g723_24_decoder(
 115         int code,
 116         int out_coding,
 117         struct g72x_state *state_ptr);
 118 extern int g723_40_encoder(
 119         int sample,
 120         int in_coding,
 121         struct g72x_state *state_ptr);
 122 extern int g723_40_decoder(
 123         int code,
 124         int out_coding,
 125         struct g72x_state *state_ptr);
 126
 127 int predictor_zero(struct g72x_state *state_ptr);
 128 int predictor_pole(struct g72x_state *state_ptr);
 129 int step_size(struct g72x_state *state_ptr);
 130 int quantize(int d,
 131              int y,
 132              short const *table,
 133              int size);
 134 int reconstruct(int sign,
 135                 int dqln,
 136                 int y);
 137 void update(int code_size,
 138             int y,
 139             int wi,
 140             int fi,
 141             int dq,
 142             int sr,
 143             int dqsez,
 144             struct g72x_state *state_ptr);
 145 int tandem_adjust_alaw(int sr,
 146                        int se,
 147                        int y,
 148                        int i,
 149                        int sign,
 150                        short const *qtab);
 151 int tandem_adjust_ulaw(int sr,
 152                        int se,
 153                        int y,
 154                        int i,
 155                        int sign,
 156                        short const *qtab);
 157 #endif /* !_G72X_H */