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2ba45a60 DM |
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 "avcodec.h" | |
26 | #include "celp_filters.h" | |
27 | #include "internal.h" | |
28 | #include "libavutil/lfg.h" | |
29 | ||
30 | typedef struct CNGContext { | |
31 | float *refl_coef, *target_refl_coef; | |
32 | float *lpc_coef; | |
33 | int order; | |
34 | int energy, target_energy; | |
35 | int inited; | |
36 | float *filter_out; | |
37 | float *excitation; | |
38 | AVLFG lfg; | |
39 | } CNGContext; | |
40 | ||
41 | static av_cold int cng_decode_close(AVCodecContext *avctx) | |
42 | { | |
43 | CNGContext *p = avctx->priv_data; | |
f6fa7814 DM |
44 | av_freep(&p->refl_coef); |
45 | av_freep(&p->target_refl_coef); | |
46 | av_freep(&p->lpc_coef); | |
47 | av_freep(&p->filter_out); | |
48 | av_freep(&p->excitation); | |
2ba45a60 DM |
49 | return 0; |
50 | } | |
51 | ||
52 | static av_cold int cng_decode_init(AVCodecContext *avctx) | |
53 | { | |
54 | CNGContext *p = avctx->priv_data; | |
55 | ||
56 | avctx->sample_fmt = AV_SAMPLE_FMT_S16; | |
57 | avctx->channels = 1; | |
58 | avctx->sample_rate = 8000; | |
59 | ||
60 | p->order = 12; | |
61 | avctx->frame_size = 640; | |
62 | p->refl_coef = av_mallocz_array(p->order, sizeof(*p->refl_coef)); | |
63 | p->target_refl_coef = av_mallocz_array(p->order, sizeof(*p->target_refl_coef)); | |
64 | p->lpc_coef = av_mallocz_array(p->order, sizeof(*p->lpc_coef)); | |
65 | p->filter_out = av_mallocz_array(avctx->frame_size + p->order, | |
66 | sizeof(*p->filter_out)); | |
67 | p->excitation = av_mallocz_array(avctx->frame_size, sizeof(*p->excitation)); | |
68 | if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef || | |
69 | !p->filter_out || !p->excitation) { | |
70 | cng_decode_close(avctx); | |
71 | return AVERROR(ENOMEM); | |
72 | } | |
73 | ||
74 | av_lfg_init(&p->lfg, 0); | |
75 | ||
76 | return 0; | |
77 | } | |
78 | ||
79 | static void make_lpc_coefs(float *lpc, const float *refl, int order) | |
80 | { | |
81 | float buf[100]; | |
82 | float *next, *cur; | |
83 | int m, i; | |
84 | next = buf; | |
85 | cur = lpc; | |
86 | for (m = 0; m < order; m++) { | |
87 | next[m] = refl[m]; | |
88 | for (i = 0; i < m; i++) | |
89 | next[i] = cur[i] + refl[m] * cur[m - i - 1]; | |
90 | FFSWAP(float*, next, cur); | |
91 | } | |
92 | if (cur != lpc) | |
93 | memcpy(lpc, cur, sizeof(*lpc) * order); | |
94 | } | |
95 | ||
96 | static void cng_decode_flush(AVCodecContext *avctx) | |
97 | { | |
98 | CNGContext *p = avctx->priv_data; | |
99 | p->inited = 0; | |
100 | } | |
101 | ||
102 | static int cng_decode_frame(AVCodecContext *avctx, void *data, | |
103 | int *got_frame_ptr, AVPacket *avpkt) | |
104 | { | |
105 | AVFrame *frame = data; | |
106 | CNGContext *p = avctx->priv_data; | |
107 | int buf_size = avpkt->size; | |
108 | int ret, i; | |
109 | int16_t *buf_out; | |
110 | float e = 1.0; | |
111 | float scaling; | |
112 | ||
113 | if (avpkt->size) { | |
114 | int dbov = -avpkt->data[0]; | |
115 | p->target_energy = 1081109975 * pow(10, dbov / 10.0) * 0.75; | |
116 | memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef)); | |
117 | for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) { | |
118 | p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0; | |
119 | } | |
120 | } | |
121 | ||
122 | if (p->inited) { | |
123 | p->energy = p->energy / 2 + p->target_energy / 2; | |
124 | for (i = 0; i < p->order; i++) | |
125 | p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i]; | |
126 | } else { | |
127 | p->energy = p->target_energy; | |
128 | memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef)); | |
129 | p->inited = 1; | |
130 | } | |
131 | make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order); | |
132 | ||
133 | for (i = 0; i < p->order; i++) | |
134 | e *= 1.0 - p->refl_coef[i]*p->refl_coef[i]; | |
135 | ||
136 | scaling = sqrt(e * p->energy / 1081109975); | |
137 | for (i = 0; i < avctx->frame_size; i++) { | |
138 | int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000; | |
139 | p->excitation[i] = scaling * r; | |
140 | } | |
141 | ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef, | |
142 | p->excitation, avctx->frame_size, p->order); | |
143 | ||
144 | frame->nb_samples = avctx->frame_size; | |
145 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) | |
146 | return ret; | |
147 | buf_out = (int16_t *)frame->data[0]; | |
148 | for (i = 0; i < avctx->frame_size; i++) | |
149 | buf_out[i] = p->filter_out[i + p->order]; | |
150 | memcpy(p->filter_out, p->filter_out + avctx->frame_size, | |
151 | p->order * sizeof(*p->filter_out)); | |
152 | ||
153 | *got_frame_ptr = 1; | |
154 | ||
155 | return buf_size; | |
156 | } | |
157 | ||
158 | AVCodec ff_comfortnoise_decoder = { | |
159 | .name = "comfortnoise", | |
160 | .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), | |
161 | .type = AVMEDIA_TYPE_AUDIO, | |
162 | .id = AV_CODEC_ID_COMFORT_NOISE, | |
163 | .priv_data_size = sizeof(CNGContext), | |
164 | .init = cng_decode_init, | |
165 | .decode = cng_decode_frame, | |
166 | .flush = cng_decode_flush, | |
167 | .close = cng_decode_close, | |
168 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, | |
169 | AV_SAMPLE_FMT_NONE }, | |
170 | .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, | |
171 | }; |