1/* 2 * RFC 3389 comfort noise generator 3 * Copyright (c) 2012 Martin Storsjo 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include <math.h> 23 24#include "libavutil/common.h" 25#include "libavutil/ffmath.h" 26#include "libavutil/intreadwrite.h" 27#include "avcodec.h" 28#include "celp_filters.h" 29#include "codec_internal.h" 30#include "internal.h" 31#include "libavutil/lfg.h" 32 33typedef struct CNGContext { 34 float *refl_coef, *target_refl_coef; 35 float *lpc_coef; 36 int order; 37 int energy, target_energy; 38 int inited; 39 float *filter_out; 40 float *excitation; 41 AVLFG lfg; 42} CNGContext; 43 44static av_cold int cng_decode_close(AVCodecContext *avctx) 45{ 46 CNGContext *p = avctx->priv_data; 47 av_freep(&p->refl_coef); 48 av_freep(&p->target_refl_coef); 49 av_freep(&p->lpc_coef); 50 av_freep(&p->filter_out); 51 av_freep(&p->excitation); 52 return 0; 53} 54 55static av_cold int cng_decode_init(AVCodecContext *avctx) 56{ 57 CNGContext *p = avctx->priv_data; 58 59 avctx->sample_fmt = AV_SAMPLE_FMT_S16; 60 av_channel_layout_uninit(&avctx->ch_layout); 61 avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO; 62 avctx->sample_rate = 8000; 63 64 p->order = 12; 65 avctx->frame_size = 640; 66 p->refl_coef = av_calloc(p->order, sizeof(*p->refl_coef)); 67 p->target_refl_coef = av_calloc(p->order, sizeof(*p->target_refl_coef)); 68 p->lpc_coef = av_calloc(p->order, sizeof(*p->lpc_coef)); 69 p->filter_out = av_calloc(avctx->frame_size + p->order, 70 sizeof(*p->filter_out)); 71 p->excitation = av_calloc(avctx->frame_size, sizeof(*p->excitation)); 72 if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef || 73 !p->filter_out || !p->excitation) { 74 return AVERROR(ENOMEM); 75 } 76 77 av_lfg_init(&p->lfg, 0); 78 79 return 0; 80} 81 82static void make_lpc_coefs(float *lpc, const float *refl, int order) 83{ 84 float buf[100]; 85 float *next, *cur; 86 int m, i; 87 next = buf; 88 cur = lpc; 89 for (m = 0; m < order; m++) { 90 next[m] = refl[m]; 91 for (i = 0; i < m; i++) 92 next[i] = cur[i] + refl[m] * cur[m - i - 1]; 93 FFSWAP(float*, next, cur); 94 } 95 if (cur != lpc) 96 memcpy(lpc, cur, sizeof(*lpc) * order); 97} 98 99static void cng_decode_flush(AVCodecContext *avctx) 100{ 101 CNGContext *p = avctx->priv_data; 102 p->inited = 0; 103} 104 105static int cng_decode_frame(AVCodecContext *avctx, AVFrame *frame, 106 int *got_frame_ptr, AVPacket *avpkt) 107{ 108 CNGContext *p = avctx->priv_data; 109 int buf_size = avpkt->size; 110 int ret, i; 111 int16_t *buf_out; 112 float e = 1.0; 113 float scaling; 114 115 if (avpkt->size) { 116 int dbov = -avpkt->data[0]; 117 p->target_energy = 1081109975 * ff_exp10(dbov / 10.0) * 0.75; 118 memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef)); 119 for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) { 120 p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0; 121 } 122 } 123 124 if (avctx->internal->skip_samples > 10 * avctx->frame_size) { 125 avctx->internal->skip_samples = 0; 126 return AVERROR_INVALIDDATA; 127 } 128 129 if (p->inited) { 130 p->energy = p->energy / 2 + p->target_energy / 2; 131 for (i = 0; i < p->order; i++) 132 p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i]; 133 } else { 134 p->energy = p->target_energy; 135 memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef)); 136 p->inited = 1; 137 } 138 make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order); 139 140 for (i = 0; i < p->order; i++) 141 e *= 1.0 - p->refl_coef[i]*p->refl_coef[i]; 142 143 scaling = sqrt(e * p->energy / 1081109975); 144 for (i = 0; i < avctx->frame_size; i++) { 145 int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000; 146 p->excitation[i] = scaling * r; 147 } 148 ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef, 149 p->excitation, avctx->frame_size, p->order); 150 151 frame->nb_samples = avctx->frame_size; 152 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) 153 return ret; 154 buf_out = (int16_t *)frame->data[0]; 155 for (i = 0; i < avctx->frame_size; i++) 156 buf_out[i] = av_clip_int16(p->filter_out[i + p->order]); 157 memcpy(p->filter_out, p->filter_out + avctx->frame_size, 158 p->order * sizeof(*p->filter_out)); 159 160 *got_frame_ptr = 1; 161 162 return buf_size; 163} 164 165const FFCodec ff_comfortnoise_decoder = { 166 .p.name = "comfortnoise", 167 .p.long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), 168 .p.type = AVMEDIA_TYPE_AUDIO, 169 .p.id = AV_CODEC_ID_COMFORT_NOISE, 170 .priv_data_size = sizeof(CNGContext), 171 .init = cng_decode_init, 172 FF_CODEC_DECODE_CB(cng_decode_frame), 173 .flush = cng_decode_flush, 174 .close = cng_decode_close, 175 .p.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, 176 AV_SAMPLE_FMT_NONE }, 177 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF, 178 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | 179 FF_CODEC_CAP_INIT_CLEANUP, 180}; 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