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4349 | Serge | 1 | /* |
2 | * RFC 3389 comfort noise generator |
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3 | * Copyright (c) 2012 Martin Storsjo |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | #include |
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23 | |||
24 | #include "libavutil/common.h" |
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25 | #include "avcodec.h" |
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26 | #include "celp_filters.h" |
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27 | #include "internal.h" |
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28 | #include "libavutil/lfg.h" |
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29 | |||
30 | typedef struct CNGContext { |
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31 | float *refl_coef, *target_refl_coef; |
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32 | float *lpc_coef; |
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33 | int order; |
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34 | int energy, target_energy; |
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35 | int inited; |
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36 | float *filter_out; |
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37 | float *excitation; |
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38 | AVLFG lfg; |
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39 | } CNGContext; |
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40 | |||
41 | static av_cold int cng_decode_close(AVCodecContext *avctx) |
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42 | { |
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43 | CNGContext *p = avctx->priv_data; |
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44 | av_free(p->refl_coef); |
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45 | av_free(p->target_refl_coef); |
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46 | av_free(p->lpc_coef); |
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47 | av_free(p->filter_out); |
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48 | av_free(p->excitation); |
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49 | return 0; |
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50 | } |
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51 | |||
52 | static av_cold int cng_decode_init(AVCodecContext *avctx) |
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53 | { |
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54 | CNGContext *p = avctx->priv_data; |
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55 | |||
56 | avctx->sample_fmt = AV_SAMPLE_FMT_S16; |
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57 | avctx->channels = 1; |
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58 | avctx->sample_rate = 8000; |
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59 | |||
60 | p->order = 12; |
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61 | avctx->frame_size = 640; |
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62 | p->refl_coef = av_mallocz(p->order * sizeof(*p->refl_coef)); |
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63 | p->target_refl_coef = av_mallocz(p->order * sizeof(*p->target_refl_coef)); |
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64 | p->lpc_coef = av_mallocz(p->order * sizeof(*p->lpc_coef)); |
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65 | p->filter_out = av_mallocz((avctx->frame_size + p->order) * |
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66 | sizeof(*p->filter_out)); |
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67 | p->excitation = av_mallocz(avctx->frame_size * sizeof(*p->excitation)); |
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68 | if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef || |
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69 | !p->filter_out || !p->excitation) { |
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70 | cng_decode_close(avctx); |
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71 | return AVERROR(ENOMEM); |
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72 | } |
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73 | |||
74 | av_lfg_init(&p->lfg, 0); |
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75 | |||
76 | return 0; |
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77 | } |
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78 | |||
79 | static void make_lpc_coefs(float *lpc, const float *refl, int order) |
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80 | { |
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81 | float buf[100]; |
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82 | float *next, *cur; |
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83 | int m, i; |
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84 | next = buf; |
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85 | cur = lpc; |
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86 | for (m = 0; m < order; m++) { |
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87 | next[m] = refl[m]; |
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88 | for (i = 0; i < m; i++) |
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89 | next[i] = cur[i] + refl[m] * cur[m - i - 1]; |
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90 | FFSWAP(float*, next, cur); |
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91 | } |
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92 | if (cur != lpc) |
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93 | memcpy(lpc, cur, sizeof(*lpc) * order); |
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94 | } |
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95 | |||
96 | static void cng_decode_flush(AVCodecContext *avctx) |
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97 | { |
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98 | CNGContext *p = avctx->priv_data; |
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99 | p->inited = 0; |
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100 | } |
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101 | |||
102 | static int cng_decode_frame(AVCodecContext *avctx, void *data, |
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103 | int *got_frame_ptr, AVPacket *avpkt) |
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104 | { |
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105 | AVFrame *frame = data; |
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106 | CNGContext *p = avctx->priv_data; |
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107 | int buf_size = avpkt->size; |
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108 | int ret, i; |
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109 | int16_t *buf_out; |
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110 | float e = 1.0; |
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111 | float scaling; |
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112 | |||
113 | if (avpkt->size) { |
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114 | int dbov = -avpkt->data[0]; |
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115 | p->target_energy = 1081109975 * pow(10, dbov / 10.0) * 0.75; |
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116 | memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef)); |
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117 | for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) { |
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118 | p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0; |
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119 | } |
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120 | } |
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121 | |||
122 | if (p->inited) { |
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123 | p->energy = p->energy / 2 + p->target_energy / 2; |
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124 | for (i = 0; i < p->order; i++) |
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125 | p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i]; |
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126 | } else { |
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127 | p->energy = p->target_energy; |
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128 | memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef)); |
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129 | p->inited = 1; |
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130 | } |
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131 | make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order); |
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132 | |||
133 | for (i = 0; i < p->order; i++) |
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134 | e *= 1.0 - p->refl_coef[i]*p->refl_coef[i]; |
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135 | |||
136 | scaling = sqrt(e * p->energy / 1081109975); |
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137 | for (i = 0; i < avctx->frame_size; i++) { |
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138 | int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000; |
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139 | p->excitation[i] = scaling * r; |
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140 | } |
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141 | ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef, |
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142 | p->excitation, avctx->frame_size, p->order); |
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143 | |||
144 | frame->nb_samples = avctx->frame_size; |
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145 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
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146 | return ret; |
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147 | buf_out = (int16_t *)frame->data[0]; |
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148 | for (i = 0; i < avctx->frame_size; i++) |
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149 | buf_out[i] = p->filter_out[i + p->order]; |
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150 | memcpy(p->filter_out, p->filter_out + avctx->frame_size, |
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151 | p->order * sizeof(*p->filter_out)); |
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152 | |||
153 | *got_frame_ptr = 1; |
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154 | |||
155 | return buf_size; |
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156 | } |
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157 | |||
158 | AVCodec ff_comfortnoise_decoder = { |
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159 | .name = "comfortnoise", |
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160 | .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), |
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161 | .type = AVMEDIA_TYPE_AUDIO, |
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162 | .id = AV_CODEC_ID_COMFORT_NOISE, |
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163 | .priv_data_size = sizeof(CNGContext), |
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164 | .init = cng_decode_init, |
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165 | .decode = cng_decode_frame, |
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166 | .flush = cng_decode_flush, |
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167 | .close = cng_decode_close, |
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168 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, |
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169 | AV_SAMPLE_FMT_NONE }, |
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170 | .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, |
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171 | };>>>>>>>> |