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i've tested, now you can too

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Brian West
2012-12-20 20:08:42 -06:00
parent d3fcfa8245
commit d67b96af8a
94 changed files with 25305 additions and 2005 deletions
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64
libs/libcodec2/src/lpc.c
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@@ -2,14 +2,14 @@
FILE........: lpc.c
AUTHOR......: David Rowe
DATE CREATED: 30/9/90
DATE CREATED: 30 Sep 1990 (!)
Linear Prediction functions written in C.
\*---------------------------------------------------------------------------*/
/*
Copyright (C) 2009 David Rowe
Copyright (C) 2009-2012 David Rowe
All rights reserved.
@@ -22,18 +22,74 @@
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#define LPC_MAX_N 512 /* maximum no. of samples in frame */
#define PI 3.141592654 /* mathematical constant */
#define ALPHA 1.0
#define BETA 0.94
#include <assert.h>
#include <math.h>
#include "defines.h"
#include "lpc.h"
/*---------------------------------------------------------------------------*\
pre_emp()
Pre-emphasise (high pass filter with zero close to 0 Hz) a frame of
speech samples. Helps reduce dynamic range of LPC spectrum, giving
greater weight and hensea better match to low energy formants.
Should be balanced by de-emphasis of the output speech.
\*---------------------------------------------------------------------------*/
void pre_emp(
float Sn_pre[], /* output frame of speech samples */
float Sn[], /* input frame of speech samples */
float *mem, /* Sn[-1]single sample memory */
int Nsam /* number of speech samples to use */
)
{
int i;
for(i=0; i<Nsam; i++) {
Sn_pre[i] = Sn[i] - ALPHA * mem[0];
mem[0] = Sn[i];
}
}
/*---------------------------------------------------------------------------*\
de_emp()
De-emphasis filter (low pass filter with polse close to 0 Hz).
\*---------------------------------------------------------------------------*/
void de_emp(
float Sn_de[], /* output frame of speech samples */
float Sn[], /* input frame of speech samples */
float *mem, /* Sn[-1]single sample memory */
int Nsam /* number of speech samples to use */
)
{
int i;
for(i=0; i<Nsam; i++) {
Sn_de[i] = Sn[i] + BETA * mem[0];
mem[0] = Sn_de[i];
}
}
/*---------------------------------------------------------------------------*\
hanning_window()