ref: 58e851b529876f97b1a5191e797097f9ed719009
dir: /lpc10/lpcdec.c/
/* * Revision 1.2 1996/08/20 20:30:11 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 22:31:48 jaf * Initial revision * */ /* -- translated by f2c (version 19951025). You must link the resulting object file with the libraries: -lf2c -lm (in that order) */ #include "f2c.h" extern int lpcdec_(integer *bits, real *speech); extern int initlpcdec_(void); /* Common Block Declarations */ extern struct { integer order, lframe; logical corrp; } contrl_; #define contrl_1 contrl_ /* Table of constant values */ static integer c__10 = 10; /* ***************************************************************** */ /* * Revision 1.2 1996/08/20 20:30:11 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 22:31:48 jaf * Initial revision * */ /* Revision 1.1 1996/03/28 00:03:00 jaf */ /* Initial revision */ /* ***************************************************************** */ /* Decode 54 bits to one frame of 180 speech samples. */ /* Input: */ /* BITS - 54 encoded bits, stored 1 per array element. */ /* Indices 1 through 53 read (SYNC bit ignored). */ /* Output: */ /* SPEECH - Speech encoded as real values in the range [-1,+1]. */ /* Indices 1 through 180 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 */ /* INITLPCDEC. */ /* Subroutine */ int lpc10_decode(integer *bits, real *speech, struct lpc10_decoder_state *st) { integer irms, voice[2], pitch, ipitv; extern /* Subroutine */ int decode_(integer *, integer *, integer *, integer *, integer *, real *, real *, struct lpc10_decoder_state *); real rc[10]; extern /* Subroutine */ int chanrd_(integer *, integer *, integer *, integer *, integer *), synths_(integer *, integer *, real *, real *, real *, integer *, struct lpc10_decoder_state *); integer irc[10], len; real rms; /* LPC Configuration parameters: */ /* Frame size, Prediction order, Pitch period */ /* Arguments */ /* LPC Processing control variables: */ /* *** Read-only: initialized in setup */ /* Files for Speech, Parameter, and Bitstream Input & Output, */ /* and message and debug outputs. */ /* Here are the only files which use these variables: */ /* lpcsim.f setup.f trans.f error.f vqsetup.f */ /* Many files which use fdebug are not listed, since it is only used in */ /* those other files conditionally, to print trace statements. */ /* integer fsi, fso, fpi, fpo, fbi, fbo, pbin, fmsg, fdebug */ /* LPC order, Frame size, Quantization rate, Bits per frame, */ /* Error correction */ /* Subroutine SETUP is the only place where order is assigned a value, */ /* and that value is 10. It could increase efficiency 1% or so to */ /* declare order as a constant (i.e., a Fortran PARAMETER) instead of as */ /* a variable in a COMMON block, since it is used in many places in the */ /* core of the coding and decoding routines. Actually, I take that back. */ /* At least when compiling with f2c, the upper bound of DO loops is */ /* stored in a local variable before the DO loop begins, and then that is */ /* compared against on each iteration. */ /* Similarly for lframe, which is given a value of MAXFRM in SETUP. */ /* Similarly for quant, which is given a value of 2400 in SETUP. quant */ /* is used in only a few places, and never in the core coding and */ /* decoding routines, so it could be eliminated entirely. */ /* nbits is similar to quant, and is given a value of 54 in SETUP. */ /* corrp is given a value of .TRUE. in SETUP, and is only used in the */ /* subroutines ENCODE and DECODE. It doesn't affect the speed of the */ /* coder significantly whether it is .TRUE. or .FALSE., or whether it is */ /* a constant or a variable, since it is only examined once per frame. */ /* Leaving it as a variable that is set to .TRUE. seems like a good */ /* idea, since it does enable some error-correction capability for */ /* unvoiced frames, with no change in the coding rate, and no noticeable */ /* quality difference in the decoded speech. */ /* integer quant, nbits */ /* *** Read/write: variables for debugging, not needed for LPC algorithm */ /* Current frame, Unstable frames, Output clip count, Max onset buffer, */ /* Debug listing detail level, Line count on listing page */ /* nframe is not needed for an embedded LPC10 at all. */ /* nunsfm is initialized to 0 in SETUP, and incremented in subroutine */ /* ERROR, which is only called from RCCHK. When LPC10 is embedded into */ /* an application, I would recommend removing the call to ERROR in RCCHK, */ /* and remove ERROR and nunsfm completely. */ /* iclip is initialized to 0 in SETUP, and incremented in entry SWRITE in */ /* sread.f. When LPC10 is embedded into an application, one might want */ /* to cause it to be incremented in a routine that takes the output of */ /* SYNTHS and sends it to an audio device. It could be optionally */ /* displayed, for those that might want to know what it is. */ /* maxosp is never initialized to 0 in SETUP, although it probably should */ /* be, and it is updated in subroutine ANALYS. I doubt that its value */ /* would be of much interest to an application in which LPC10 is */ /* embedded. */ /* listl and lincnt are not needed for an embedded LPC10 at all. */ /* integer nframe, nunsfm, iclip, maxosp, listl, lincnt */ /* common /contrl/ fsi, fso, fpi, fpo, fbi, fbo, pbin, fmsg, fdebug */ /* common /contrl/ quant, nbits */ /* common /contrl/ nframe, nunsfm, iclip, maxosp, listl, lincnt */ /* Local variables that need not be saved */ /* Uncoded speech parameters */ /* Coded speech parameters */ /* Others */ /* Local state */ /* None */ /* Parameter adjustments */ if (bits) { --bits; } if (speech) { --speech; } /* Function Body */ chanrd_(&c__10, &ipitv, &irms, irc, &bits[1]); decode_(&ipitv, &irms, irc, voice, &pitch, &rms, rc, st); synths_(voice, &pitch, &rms, rc, &speech[1], &len, st); return 0; } /* lpcdec_ */