1 /*
2 ** Copyright 2003-2010, VisualOn, Inc.
3 **
4 ** Licensed under the Apache License, Version 2.0 (the "License");
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
8 ** http://www.apache.org/licenses/LICENSE-2.0
9 **
10 ** Unless required by applicable law or agreed to in writing, software
11 ** distributed under the License is distributed on an "AS IS" BASIS,
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16
17 /**************************************************************************
18 * File: gpclip.c *
19 * *
20 * Description:To avoid unstable synthesis on frame erasure, the gain *
21 * need to be limited(gain pitch < 1.0) when the following *
22 * case occurs *
23 * a resonance on LPC filter(lp_disp < 60Hz) *
24 * a good pitch prediction (lp_gp > 0.95) *
25 * *
26 ***************************************************************************/
27 #include "typedef.h"
28 #include "basic_op.h"
29
30 #define DIST_ISF_MAX 307 /* 120 Hz (6400Hz=16384) */
31 #define DIST_ISF_THRES 154 /* 60 (6400Hz=16384) */
32 #define GAIN_PIT_THRES 14746 /* 0.9 in Q14 */
33 #define GAIN_PIT_MIN 9830 /* 0.6 in Q14 */
34 #define M 16
35
36
Init_gp_clip(Word16 mem[])37 void Init_gp_clip(
38 Word16 mem[] /* (o) : memory of gain of pitch clipping algorithm */
39 )
40 {
41 mem[0] = DIST_ISF_MAX;
42 mem[1] = GAIN_PIT_MIN;
43 }
44
45
Gp_clip(Word16 mem[])46 Word16 Gp_clip(
47 Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
48 )
49 {
50 Word16 clip = 0;
51 if ((mem[0] < DIST_ISF_THRES) && (mem[1] > GAIN_PIT_THRES))
52 clip = 1;
53
54 return (clip);
55 }
56
57
Gp_clip_test_isf(Word16 isf[],Word16 mem[])58 void Gp_clip_test_isf(
59 Word16 isf[], /* (i) : isf values (in frequency domain) */
60 Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
61 )
62 {
63 Word16 dist, dist_min;
64 Word32 i;
65
66 dist_min = vo_sub(isf[1], isf[0]);
67
68 for (i = 2; i < M - 1; i++)
69 {
70 dist = vo_sub(isf[i], isf[i - 1]);
71 if(dist < dist_min)
72 {
73 dist_min = dist;
74 }
75 }
76
77 dist = extract_h(L_mac(vo_L_mult(26214, mem[0]), 6554, dist_min));
78
79 if (dist > DIST_ISF_MAX)
80 {
81 dist = DIST_ISF_MAX;
82 }
83 mem[0] = dist;
84
85 return;
86 }
87
88
Gp_clip_test_gain_pit(Word16 gain_pit,Word16 mem[])89 void Gp_clip_test_gain_pit(
90 Word16 gain_pit, /* (i) Q14 : gain of quantized pitch */
91 Word16 mem[] /* (i/o) : memory of gain of pitch clipping algorithm */
92 )
93 {
94 Word16 gain;
95 Word32 L_tmp;
96 L_tmp = (29491 * mem[1])<<1;
97 L_tmp += (3277 * gain_pit)<<1;
98
99 gain = extract_h(L_tmp);
100
101 if(gain < GAIN_PIT_MIN)
102 {
103 gain = GAIN_PIT_MIN;
104 }
105 mem[1] = gain;
106 return;
107 }
108
109
110
111