1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
/*
* RFC 3389 comfort noise generator
* Copyright (c) 2012 Martin Storsjo
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include "libavutil/common.h"
#include "avcodec.h"
#include "celp_filters.h"
#include "libavutil/lfg.h"
typedef struct CNGContext {
AVFrame avframe;
float *refl_coef, *target_refl_coef;
float *lpc_coef;
int order;
int energy, target_energy;
int inited;
float *filter_out;
float *excitation;
AVLFG lfg;
} CNGContext;
static av_cold int cng_decode_close(AVCodecContext *avctx)
{
CNGContext *p = avctx->priv_data;
av_free(p->refl_coef);
av_free(p->target_refl_coef);
av_free(p->lpc_coef);
av_free(p->filter_out);
av_free(p->excitation);
return 0;
}
static av_cold int cng_decode_init(AVCodecContext *avctx)
{
CNGContext *p = avctx->priv_data;
avctx->sample_fmt = AV_SAMPLE_FMT_S16;
avctx->channels = 1;
avctx->sample_rate = 8000;
avcodec_get_frame_defaults(&p->avframe);
avctx->coded_frame = &p->avframe;
p->order = 12;
avctx->frame_size = 640;
p->refl_coef = av_mallocz(p->order * sizeof(*p->refl_coef));
p->target_refl_coef = av_mallocz(p->order * sizeof(*p->target_refl_coef));
p->lpc_coef = av_mallocz(p->order * sizeof(*p->lpc_coef));
p->filter_out = av_mallocz((avctx->frame_size + p->order) *
sizeof(*p->filter_out));
p->excitation = av_mallocz(avctx->frame_size * sizeof(*p->excitation));
if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef ||
!p->filter_out || !p->excitation) {
cng_decode_close(avctx);
return AVERROR(ENOMEM);
}
av_lfg_init(&p->lfg, 0);
return 0;
}
static void make_lpc_coefs(float *lpc, const float *refl, int order)
{
float buf[100];
float *next, *cur;
int m, i;
next = buf;
cur = lpc;
for (m = 0; m < order; m++) {
next[m] = refl[m];
for (i = 0; i < m; i++)
next[i] = cur[i] + refl[m] * cur[m - i - 1];
FFSWAP(float*, next, cur);
}
if (cur != lpc)
memcpy(lpc, cur, sizeof(*lpc) * order);
}
static void cng_decode_flush(AVCodecContext *avctx)
{
CNGContext *p = avctx->priv_data;
p->inited = 0;
}
static int cng_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
CNGContext *p = avctx->priv_data;
int buf_size = avpkt->size;
int ret, i;
int16_t *buf_out;
float e = 1.0;
float scaling;
if (avpkt->size) {
int dbov = -avpkt->data[0];
p->target_energy = 1081109975 * pow(10, dbov / 10.0) * 0.75;
memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef));
for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) {
p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0;
}
}
if (p->inited) {
p->energy = p->energy / 2 + p->target_energy / 2;
for (i = 0; i < p->order; i++)
p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i];
} else {
p->energy = p->target_energy;
memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef));
p->inited = 1;
}
make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order);
for (i = 0; i < p->order; i++)
e *= 1.0 - p->refl_coef[i]*p->refl_coef[i];
scaling = sqrt(e * p->energy / 1081109975);
for (i = 0; i < avctx->frame_size; i++) {
int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000;
p->excitation[i] = scaling * r;
}
ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef,
p->excitation, avctx->frame_size, p->order);
p->avframe.nb_samples = avctx->frame_size;
if ((ret = avctx->get_buffer(avctx, &p->avframe)) < 0) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return ret;
}
buf_out = (int16_t *)p->avframe.data[0];
for (i = 0; i < avctx->frame_size; i++)
buf_out[i] = p->filter_out[i + p->order];
memcpy(p->filter_out, p->filter_out + avctx->frame_size,
p->order * sizeof(*p->filter_out));
*got_frame_ptr = 1;
*(AVFrame *)data = p->avframe;
return buf_size;
}
AVCodec ff_comfortnoise_decoder = {
.name = "comfortnoise",
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_COMFORT_NOISE,
.priv_data_size = sizeof(CNGContext),
.init = cng_decode_init,
.decode = cng_decode_frame,
.flush = cng_decode_flush,
.close = cng_decode_close,
.long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
AV_SAMPLE_FMT_NONE },
.capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1,
};
|
