diff options
Diffstat (limited to '1.4.23-rc4/codecs/lpc10/ivfilt.c')
| -rw-r--r-- | 1.4.23-rc4/codecs/lpc10/ivfilt.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/1.4.23-rc4/codecs/lpc10/ivfilt.c b/1.4.23-rc4/codecs/lpc10/ivfilt.c new file mode 100644 index 000000000..784de2571 --- /dev/null +++ b/1.4.23-rc4/codecs/lpc10/ivfilt.c @@ -0,0 +1,136 @@ +/* + +$Log$ +Revision 1.16 2004/06/26 03:50:14 markster +Merge source cleanups (bug #1911) + +Revision 1.15 2003/09/19 01:20:22 markster +Code cleanups (bug #66) + +Revision 1.2 2003/09/19 01:20:22 markster +Code cleanups (bug #66) + +Revision 1.1.1.1 2003/02/12 13:59:15 matteo +mer feb 12 14:56:57 CET 2003 + +Revision 1.2 2000/01/05 08:20:39 markster +Some OSS fixes and a few lpc changes to make it actually work + + * Revision 1.1 1996/08/19 22:31:53 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" + +#ifdef P_R_O_T_O_T_Y_P_E_S +extern int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *nsamp, real *ivrc); +#endif + +/* ********************************************************************* */ + +/* IVFILT Version 48 */ + +/* $Log$ + * Revision 1.16 2004/06/26 03:50:14 markster + * Merge source cleanups (bug #1911) + * + * Revision 1.15 2003/09/19 01:20:22 markster + * Code cleanups (bug #66) + * + * Revision 1.2 2003/09/19 01:20:22 markster + * Code cleanups (bug #66) + * + * Revision 1.1.1.1 2003/02/12 13:59:15 matteo + * mer feb 12 14:56:57 CET 2003 + * + * Revision 1.2 2000/01/05 08:20:39 markster + * Some OSS fixes and a few lpc changes to make it actually work + * + * Revision 1.1 1996/08/19 22:31:53 jaf + * Initial revision + * */ +/* Revision 1.3 1996/03/15 21:36:29 jaf */ +/* Just added a few comments about which array indices of the arguments */ +/* are used, and mentioning that this subroutine has no local state. */ + +/* Revision 1.2 1996/03/13 00:01:00 jaf */ +/* Comments added explaining that none of the local variables of this */ +/* subroutine need to be saved from one invocation to the next. */ + +/* Revision 1.1 1996/02/07 14:47:34 jaf */ +/* Initial revision */ + + +/* ********************************************************************* */ + +/* 2nd order inverse filter, speech is decimated 4:1 */ + +/* Input: */ +/* LEN - Length of speech buffers */ +/* NSAMP - Number of samples to filter */ +/* LPBUF - Low pass filtered speech buffer */ +/* Indices LEN-NSAMP-7 through LEN read. */ +/* Output: */ +/* IVBUF - Inverse filtered speech buffer */ +/* Indices LEN-NSAMP+1 through LEN written. */ +/* IVRC - Inverse filter reflection coefficients (for voicing) */ +/* Indices 1 and 2 both written (also read, but only after writing). +*/ + +/* This subroutine has no local state. */ + +/* Subroutine */ int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer * + nsamp, real *ivrc) +{ + /* System generated locals */ + integer i__1; + + /* Local variables */ + integer i__, j, k; + real r__[3], pc1, pc2; + +/* Arguments */ +/* Local variables that need not be saved */ +/* Local state */ +/* None */ +/* Calculate Autocorrelations */ + /* Parameter adjustments */ + --ivbuf; + --lpbuf; + --ivrc; + + /* Function Body */ + for (i__ = 1; i__ <= 3; ++i__) { + r__[i__ - 1] = 0.f; + k = (i__ - 1) << 2; + i__1 = *len; + for (j = (i__ << 2) + *len - *nsamp; j <= i__1; j += 2) { + r__[i__ - 1] += lpbuf[j] * lpbuf[j - k]; + } + } +/* Calculate predictor coefficients */ + pc1 = 0.f; + pc2 = 0.f; + ivrc[1] = 0.f; + ivrc[2] = 0.f; + if (r__[0] > 1e-10f) { + ivrc[1] = r__[1] / r__[0]; + ivrc[2] = (r__[2] - ivrc[1] * r__[1]) / (r__[0] - ivrc[1] * r__[1]); + pc1 = ivrc[1] - ivrc[1] * ivrc[2]; + pc2 = ivrc[2]; + } +/* Inverse filter LPBUF into IVBUF */ + i__1 = *len; + for (i__ = *len + 1 - *nsamp; i__ <= i__1; ++i__) { + ivbuf[i__] = lpbuf[i__] - pc1 * lpbuf[i__ - 4] - pc2 * lpbuf[i__ - 8]; + } + return 0; +} /* ivfilt_ */ + |