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/*
** Copyright 2003-2010, VisualOn, Inc.
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
/**************************************************************************
* File: gpclip.c *
* *
* Description:To avoid unstable synthesis on frame erasure, the gain *
* need to be limited(gain pitch < 1.0) when the following *
* case occurs *
* a resonance on LPC filter(lp_disp < 60Hz) *
* a good pitch prediction (lp_gp > 0.95) *
* *
***************************************************************************/
#include "typedef.h"
#include "basic_op.h"
#define DIST_ISF_MAX 307 /* 120 Hz (6400Hz=16384) */
#define DIST_ISF_THRES 154 /* 60 (6400Hz=16384) */
#define GAIN_PIT_THRES 14746 /* 0.9 in Q14 */
#define GAIN_PIT_MIN 9830 /* 0.6 in Q14 */
#define M 16
void Init_gp_clip(
Word16 mem[] /* (o) : memory of gain of pitch clipping algorithm */
)
{
mem[0] = DIST_ISF_MAX;
mem[1] = GAIN_PIT_MIN;
}
Word16 Gp_clip(
Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
)
{
Word16 clip = 0;
if ((mem[0] < DIST_ISF_THRES) && (mem[1] > GAIN_PIT_THRES))
clip = 1;
return (clip);
}
void Gp_clip_test_isf(
Word16 isf[], /* (i) : isf values (in frequency domain) */
Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
)
{
Word16 dist, dist_min;
Word32 i;
dist_min = vo_sub(isf[1], isf[0]);
for (i = 2; i < M - 1; i++)
{
dist = vo_sub(isf[i], isf[i - 1]);
if(dist < dist_min)
{
dist_min = dist;
}
}
dist = extract_h(L_mac(vo_L_mult(26214, mem[0]), 6554, dist_min));
if (dist > DIST_ISF_MAX)
{
dist = DIST_ISF_MAX;
}
mem[0] = dist;
return;
}
void Gp_clip_test_gain_pit(
Word16 gain_pit, /* (i) Q14 : gain of quantized pitch */
Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
)
{
Word16 gain;
Word32 L_tmp;
L_tmp = (29491 * mem[1])<<1;
L_tmp += (3277 * gain_pit)<<1;
gain = extract_h(L_tmp);
if(gain < GAIN_PIT_MIN)
{
gain = GAIN_PIT_MIN;
}
mem[1] = gain;
return;
}
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