lpcenc.c

lpc10-15为美军2400bps语音压缩标准的C语音源代码。

/*

$Log: lpcenc.c,v $
 * Revision 1.2  1996/08/20  20:31:21  jaf
 * Removed all static local variables that were SAVE'd in the Fortran
 * code, and put them in struct lpc10_encoder_state that is passed as an
 * argument.
 *
 * Removed init function, since all initialization is now done in
 * init_lpc10_encoder_state().
 *
 * Changed name of function from lpcenc_ to lpc10_encode, simply to make
 * all lpc10 functions have more consistent naming with each other.
 *
 * Revision 1.1  1996/08/19  22:31:44  jaf
 * Initial revision
 *

*/

#ifdef P_R_O_T_O_T_Y_P_E_S
extern int lpcenc_(real *speech, integer *bits);
extern int initlpcenc_(void);
/*:ref: prepro_ 14 2 6 4 */
/*:ref: analys_ 14 5 6 4 4 6 6 */
/*:ref: encode_ 14 7 4 4 6 6 4 4 4 */
/*:ref: chanwr_ 14 5 4 4 4 4 4 */
/*:ref: initprepro_ 14 0 */
/*:ref: initanalys_ 14 0 */
#endif

/*  -- translated by f2c (version 19951025).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* Table of constant values */

static integer c__180 = 180;
static integer c__10 = 10;

/* ***************************************************************** */

/* $Log: lpcenc.c,v $
 * Revision 1.2  1996/08/20  20:31:21  jaf
 * Removed all static local variables that were SAVE'd in the Fortran
 * code, and put them in struct lpc10_encoder_state that is passed as an
 * argument.
 *
 * Removed init function, since all initialization is now done in
 * init_lpc10_encoder_state().
 *
 * Changed name of function from lpcenc_ to lpc10_encode, simply to make
 * all lpc10 functions have more consistent naming with each other.
 *
 * Revision 1.1  1996/08/19  22:31:44  jaf
 * Initial revision
 * */
/* Revision 1.2  1996/03/28  00:01:22  jaf */
/* Commented out some trace statements. */

/* Revision 1.1  1996/03/28  00:00:27  jaf */
/* Initial revision */


/* ***************************************************************** */

/* Encode one frame of 180 speech samples to 54 bits. */

/* Input: */
/*  SPEECH - Speech encoded as real values in the range [-1,+1]. */
/*           Indices 1 through 180 read, and modified (by PREPRO). */
/* Output: */
/*  BITS   - 54 encoded bits, stored 1 per array element. */
/*           Indices 1 through 54 written. */

/* This subroutine maintains local state from one call to the next.  If */
/* you want to switch to using a new audio stream for this filter, or */
/* reinitialize its state for any other reason, call the ENTRY */
/* INITLPCENC. */

/* Subroutine */ int lpc10_encode(real *speech, integer *bits,
				  struct lpc10_encoder_state *st)
{
    integer irms, voice[2], pitch, ipitv;
    real rc[10];
    extern /* Subroutine */ int encode_(integer *, integer *, real *, real *, 
	    integer *, integer *, integer *), chanwr_(integer *, integer *, 
	    integer *, integer *, integer *, struct lpc10_encoder_state *),
            analys_(real *, integer *, 
	    integer *, real *, real *, struct lpc10_encoder_state *),
            prepro_(real *, integer *, struct lpc10_encoder_state *);
    integer irc[10];
    real rms;

/*       Arguments */
/* $Log: lpcenc.c,v $
 * Revision 1.2  1996/08/20  20:31:21  jaf
 * Removed all static local variables that were SAVE'd in the Fortran
 * code, and put them in struct lpc10_encoder_state that is passed as an
 * argument.
 *
 * Removed init function, since all initialization is now done in
 * init_lpc10_encoder_state().
 *
 * Changed name of function from lpcenc_ to lpc10_encode, simply to make
 * all lpc10 functions have more consistent naming with each other.
 *
 * Revision 1.1  1996/08/19  22:31:44  jaf
 * Initial revision
 * */
/* Revision 1.3  1996/03/29  22:03:47  jaf */
/* Removed definitions for any constants that were no longer used. */

/* Revision 1.2  1996/03/26  19:34:33  jaf */
/* Added comments indicating which constants are not needed in an */
/* application that uses the LPC-10 coder. */

/* Revision 1.1  1996/02/07  14:43:51  jaf */
/* Initial revision */

/*   LPC Configuration parameters: */
/* Frame size, Prediction order, Pitch period */
/*       Local variables that need not be saved */
/*       Uncoded speech parameters */
/*       Coded speech parameters */
/*       Local state */
/*       None */
    /* Parameter adjustments */
    if (speech) {
	--speech;
	}
    if (bits) {
	--bits;
	}

    /* Function Body */
    prepro_(&speech[1], &c__180, st);
    analys_(&speech[1], voice, &pitch, &rms, rc, st);
    encode_(voice, &pitch, &rms, rc, &ipitv, &irms, irc);
    chanwr_(&c__10, &ipitv, &irms, irc, &bits[1], st);
    return 0;
} /* lpcenc_ */