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 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 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 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 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
