lpc10/lpcdec.c

   1 /*
   2
   3  * Revision 1.2  1996/08/20  20:30:11  jaf
   4  * Removed all static local variables that were SAVE'd in the Fortran
   5  * code, and put them in struct lpc10_encoder_state that is passed as an
   6  * argument.
   7  *
   8  * Removed init function, since all initialization is now done in
   9  * init_lpc10_encoder_state().
  10  *
  11  * Changed name of function from lpcenc_ to lpc10_encode, simply to make
  12  * all lpc10 functions have more consistent naming with each other.
  13  *
  14  * Revision 1.1  1996/08/19  22:31:48  jaf
  15  * Initial revision
  16  *
  17
  18 */
  19
  20 /*  -- translated by f2c (version 19951025).
  21    You must link the resulting object file with the libraries:
  22         -lf2c -lm   (in that order)
  23 */
  24
  25 #include "f2c.h"
  26
  27 extern int lpcdec_(integer *bits, real *speech);
  28 extern int initlpcdec_(void);
  29
  30 /* Common Block Declarations */
  31
  32 extern struct {
  33     integer order, lframe;
  34     logical corrp;
  35 } contrl_;
  36
  37 #define contrl_1 contrl_
  38
  39 /* Table of constant values */
  40
  41 static integer c__10 = 10;
  42
  43 /* ***************************************************************** */
  44
  45 /*
  46  * Revision 1.2  1996/08/20  20:30:11  jaf
  47  * Removed all static local variables that were SAVE'd in the Fortran
  48  * code, and put them in struct lpc10_encoder_state that is passed as an
  49  * argument.
  50  *
  51  * Removed init function, since all initialization is now done in
  52  * init_lpc10_encoder_state().
  53  *
  54  * Changed name of function from lpcenc_ to lpc10_encode, simply to make
  55  * all lpc10 functions have more consistent naming with each other.
  56  *
  57  * Revision 1.1  1996/08/19  22:31:48  jaf
  58  * Initial revision
  59  * */
  60 /* Revision 1.1  1996/03/28  00:03:00  jaf */
  61 /* Initial revision */
  62
  63
  64 /* ***************************************************************** */
  65
  66 /* Decode 54 bits to one frame of 180 speech samples. */
  67
  68 /* Input: */
  69 /*  BITS   - 54 encoded bits, stored 1 per array element. */
  70 /*           Indices 1 through 53 read (SYNC bit ignored). */
  71 /* Output: */
  72 /*  SPEECH - Speech encoded as real values in the range [-1,+1]. */
  73 /*           Indices 1 through 180 written. */
  74
  75 /* This subroutine maintains local state from one call to the next.  If */
  76 /* you want to switch to using a new audio stream for this filter, or */
  77 /* reinitialize its state for any other reason, call the ENTRY */
  78 /* INITLPCDEC. */
  79
  80 /* Subroutine */ int lpc10_decode(integer *bits, real *speech,
  81                                   struct lpc10_decoder_state *st)
  82 {
  83     integer irms, voice[2], pitch, ipitv;
  84     extern /* Subroutine */ int decode_(integer *, integer *, integer *,
  85             integer *, integer *, real *, real *, struct lpc10_decoder_state *);
  86     real rc[10];
  87     extern /* Subroutine */ int chanrd_(integer *, integer *, integer *,
  88             integer *, integer *), synths_(integer *,
  89             integer *, real *, real *, real *, integer *,
  90                                            struct lpc10_decoder_state *);
  91     integer irc[10], len;
  92     real rms;
  93
  94
  95 /*   LPC Configuration parameters: */
  96 /* Frame size, Prediction order, Pitch period */
  97 /*       Arguments */
  98 /*   LPC Processing control variables: */
  99
 100 /* *** Read-only: initialized in setup */
 101
 102 /*  Files for Speech, Parameter, and Bitstream Input & Output, */
 103 /*    and message and debug outputs. */
 104
 105 /* Here are the only files which use these variables: */
 106
 107 /* lpcsim.f setup.f trans.f error.f vqsetup.f */
 108
 109 /* Many files which use fdebug are not listed, since it is only used in */
 110 /* those other files conditionally, to print trace statements. */
 111 /*      integer fsi, fso, fpi, fpo, fbi, fbo, pbin, fmsg, fdebug */
 112 /*  LPC order, Frame size, Quantization rate, Bits per frame, */
 113 /*    Error correction */
 114 /* Subroutine SETUP is the only place where order is assigned a value, */
 115 /* and that value is 10.  It could increase efficiency 1% or so to */
 116 /* declare order as a constant (i.e., a Fortran PARAMETER) instead of as
 117 */
 118 /* a variable in a COMMON block, since it is used in many places in the */
 119 /* core of the coding and decoding routines.  Actually, I take that back.
 120 */
 121 /* At least when compiling with f2c, the upper bound of DO loops is */
 122 /* stored in a local variable before the DO loop begins, and then that is
 123 */
 124 /* compared against on each iteration. */
 125 /* Similarly for lframe, which is given a value of MAXFRM in SETUP. */
 126 /* Similarly for quant, which is given a value of 2400 in SETUP.  quant */
 127 /* is used in only a few places, and never in the core coding and */
 128 /* decoding routines, so it could be eliminated entirely. */
 129 /* nbits is similar to quant, and is given a value of 54 in SETUP. */
 130 /* corrp is given a value of .TRUE. in SETUP, and is only used in the */
 131 /* subroutines ENCODE and DECODE.  It doesn't affect the speed of the */
 132 /* coder significantly whether it is .TRUE. or .FALSE., or whether it is
 133 */
 134 /* a constant or a variable, since it is only examined once per frame. */
 135 /* Leaving it as a variable that is set to .TRUE.  seems like a good */
 136 /* idea, since it does enable some error-correction capability for */
 137 /* unvoiced frames, with no change in the coding rate, and no noticeable
 138 */
 139 /* quality difference in the decoded speech. */
 140 /*      integer quant, nbits */
 141 /* *** Read/write: variables for debugging, not needed for LPC algorithm
 142 */
 143
 144 /*  Current frame, Unstable frames, Output clip count, Max onset buffer,
 145 */
 146 /*    Debug listing detail level, Line count on listing page */
 147
 148 /* nframe is not needed for an embedded LPC10 at all. */
 149 /* nunsfm is initialized to 0 in SETUP, and incremented in subroutine */
 150 /* ERROR, which is only called from RCCHK.  When LPC10 is embedded into */
 151 /* an application, I would recommend removing the call to ERROR in RCCHK,
 152 */
 153 /* and remove ERROR and nunsfm completely. */
 154 /* iclip is initialized to 0 in SETUP, and incremented in entry SWRITE in
 155 */
 156 /* sread.f.  When LPC10 is embedded into an application, one might want */
 157 /* to cause it to be incremented in a routine that takes the output of */
 158 /* SYNTHS and sends it to an audio device.  It could be optionally */
 159 /* displayed, for those that might want to know what it is. */
 160 /* maxosp is never initialized to 0 in SETUP, although it probably should
 161 */
 162 /* be, and it is updated in subroutine ANALYS.  I doubt that its value */
 163 /* would be of much interest to an application in which LPC10 is */
 164 /* embedded. */
 165 /* listl and lincnt are not needed for an embedded LPC10 at all. */
 166 /*      integer nframe, nunsfm, iclip, maxosp, listl, lincnt */
 167 /*      common /contrl/ fsi, fso, fpi, fpo, fbi, fbo, pbin, fmsg, fdebug */
 168 /*      common /contrl/ quant, nbits */
 169 /*      common /contrl/ nframe, nunsfm, iclip, maxosp, listl, lincnt */
 170 /*       Local variables that need not be saved */
 171 /*       Uncoded speech parameters */
 172 /*       Coded speech parameters */
 173 /*       Others */
 174 /*       Local state */
 175 /*       None */
 176     /* Parameter adjustments */
 177     if (bits) {
 178         --bits;
 179         }
 180     if (speech) {
 181         --speech;
 182         }
 183
 184     /* Function Body */
 185
 186     chanrd_(&c__10, &ipitv, &irms, irc, &bits[1]);
 187     decode_(&ipitv, &irms, irc, voice, &pitch, &rms, rc, st);
 188     synths_(voice, &pitch, &rms, rc, &speech[1], &len, st);
 189     return 0;
 190 } /* lpcdec_ */