151 lines
4.2 KiB
C
151 lines
4.2 KiB
C
/*
|
|
* SpanDSP - a series of DSP components for telephony
|
|
*
|
|
* gsm0610_preprocess.c - GSM 06.10 full rate speech codec.
|
|
*
|
|
* Written by Steve Underwood <steveu@coppice.org>
|
|
*
|
|
* Copyright (C) 2006 Steve Underwood
|
|
*
|
|
* All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU Lesser General Public License version 2.1,
|
|
* as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU Lesser General Public 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.
|
|
*
|
|
* This code is based on the widely used GSM 06.10 code available from
|
|
* http://kbs.cs.tu-berlin.de/~jutta/toast.html
|
|
*/
|
|
|
|
/*! \file */
|
|
|
|
#if defined(HAVE_CONFIG_H)
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include <assert.h>
|
|
#include <inttypes.h>
|
|
#if defined(HAVE_TGMATH_H)
|
|
#include <tgmath.h>
|
|
#endif
|
|
#if defined(HAVE_MATH_H)
|
|
#include <math.h>
|
|
#endif
|
|
#include "floating_fudge.h"
|
|
#include <stdlib.h>
|
|
|
|
#include "spandsp/telephony.h"
|
|
#include "spandsp/fast_convert.h"
|
|
#include "spandsp/bitstream.h"
|
|
#include "spandsp/saturated.h"
|
|
#include "spandsp/gsm0610.h"
|
|
|
|
#include "gsm0610_local.h"
|
|
|
|
/*
|
|
4.2.0 .. 4.2.3 PREPROCESSING SECTION
|
|
|
|
After A-law to linear conversion (or directly from the
|
|
A to D converter) the following scaling is assumed for
|
|
input to the RPE-LTP algorithm:
|
|
|
|
in: 0.1.....................12
|
|
S.v.v.v.v.v.v.v.v.v.v.v.v.*.*.*
|
|
|
|
Where S is the sign bit, v a valid bit, and * a "don't care" bit.
|
|
The original signal is called sop[..]
|
|
|
|
out: 0.1................... 12
|
|
S.S.v.v.v.v.v.v.v.v.v.v.v.v.0.0
|
|
*/
|
|
|
|
void gsm0610_preprocess(gsm0610_state_t *s, const int16_t amp[GSM0610_FRAME_LEN], int16_t so[GSM0610_FRAME_LEN])
|
|
{
|
|
int16_t z1;
|
|
int16_t mp;
|
|
int16_t s1;
|
|
int16_t msp;
|
|
int16_t SO;
|
|
int32_t L_z2;
|
|
int32_t L_s2;
|
|
int32_t L_temp;
|
|
#if !defined(__GNUC__)
|
|
int16_t lsp;
|
|
#endif
|
|
int k;
|
|
|
|
z1 = s->z1;
|
|
L_z2 = s->L_z2;
|
|
mp = s->mp;
|
|
for (k = 0; k < GSM0610_FRAME_LEN; k++)
|
|
{
|
|
/* 4.2.1 Downscaling of the input signal */
|
|
SO = (amp[k] >> 1) & ~3;
|
|
|
|
/* This is supposed to have been downscaled by previous routine. */
|
|
assert(SO >= -0x4000);
|
|
assert(SO <= 0x3FFC);
|
|
|
|
/* 4.2.2 Offset compensation */
|
|
|
|
/* This part implements a high-pass filter and requires extended
|
|
arithmetic precision for the recursive part of this filter.
|
|
The input of this procedure is the array so[0...159] and the
|
|
output the array sof[0...159].
|
|
*/
|
|
/* Compute the non-recursive part */
|
|
s1 = SO - z1;
|
|
z1 = SO;
|
|
|
|
assert(s1 != INT16_MIN);
|
|
|
|
/* Compute the recursive part */
|
|
L_s2 = s1;
|
|
L_s2 <<= 15;
|
|
|
|
/* Perform a 31 by 16 bits multiplication */
|
|
#if defined(__GNUC__)
|
|
L_z2 = ((int64_t) L_z2*32735 + 0x4000) >> 15;
|
|
/* Alternate (ANSI) version of below line does slightly different rounding:
|
|
* L_temp = L_z2 >> 9;
|
|
* L_temp += L_temp >> 5;
|
|
* L_temp = (++L_temp) >> 1;
|
|
* L_z2 = L_z2 - L_temp;
|
|
*/
|
|
L_z2 = sat_add32(L_z2, L_s2);
|
|
#else
|
|
/* This does L_z2 = L_z2 * 0x7FD5/0x8000 + L_s2 */
|
|
msp = (int16_t) (L_z2 >> 15);
|
|
lsp = (int16_t) (L_z2 - ((int32_t) msp << 15));
|
|
|
|
L_s2 += gsm_mult_r(lsp, 32735);
|
|
L_temp = (int32_t) msp*32735;
|
|
L_z2 = sat_add32(L_temp, L_s2);
|
|
#endif
|
|
|
|
/* Compute sof[k] with rounding */
|
|
L_temp = sat_add32(L_z2, 16384);
|
|
|
|
/* 4.2.3 Preemphasis */
|
|
msp = gsm_mult_r(mp, -28180);
|
|
mp = (int16_t) (L_temp >> 15);
|
|
so[k] = sat_add16(mp, msp);
|
|
}
|
|
/*endfor*/
|
|
|
|
s->z1 = z1;
|
|
s->L_z2 = L_z2;
|
|
s->mp = mp;
|
|
}
|
|
/*- End of function --------------------------------------------------------*/
|
|
/*- End of file ------------------------------------------------------------*/
|