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cngdec.c
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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 "avcodec.h"
27 #include "celp_filters.h"
28 #include "internal.h"
29 #include "libavutil/lfg.h"
30 
31 typedef struct CNGContext {
33  float *lpc_coef;
34  int order;
36  int inited;
37  float *filter_out;
38  float *excitation;
40 } CNGContext;
41 
43 {
44  CNGContext *p = avctx->priv_data;
45  av_freep(&p->refl_coef);
47  av_freep(&p->lpc_coef);
48  av_freep(&p->filter_out);
49  av_freep(&p->excitation);
50  return 0;
51 }
52 
54 {
55  CNGContext *p = avctx->priv_data;
56 
58  avctx->channels = 1;
59  avctx->sample_rate = 8000;
60 
61  p->order = 12;
62  avctx->frame_size = 640;
63  p->refl_coef = av_mallocz_array(p->order, sizeof(*p->refl_coef));
65  p->lpc_coef = av_mallocz_array(p->order, sizeof(*p->lpc_coef));
67  sizeof(*p->filter_out));
68  p->excitation = av_mallocz_array(avctx->frame_size, sizeof(*p->excitation));
69  if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef ||
70  !p->filter_out || !p->excitation) {
71  cng_decode_close(avctx);
72  return AVERROR(ENOMEM);
73  }
74 
75  av_lfg_init(&p->lfg, 0);
76 
77  return 0;
78 }
79 
80 static void make_lpc_coefs(float *lpc, const float *refl, int order)
81 {
82  float buf[100];
83  float *next, *cur;
84  int m, i;
85  next = buf;
86  cur = lpc;
87  for (m = 0; m < order; m++) {
88  next[m] = refl[m];
89  for (i = 0; i < m; i++)
90  next[i] = cur[i] + refl[m] * cur[m - i - 1];
91  FFSWAP(float*, next, cur);
92  }
93  if (cur != lpc)
94  memcpy(lpc, cur, sizeof(*lpc) * order);
95 }
96 
97 static void cng_decode_flush(AVCodecContext *avctx)
98 {
99  CNGContext *p = avctx->priv_data;
100  p->inited = 0;
101 }
102 
103 static int cng_decode_frame(AVCodecContext *avctx, void *data,
104  int *got_frame_ptr, AVPacket *avpkt)
105 {
106  AVFrame *frame = data;
107  CNGContext *p = avctx->priv_data;
108  int buf_size = avpkt->size;
109  int ret, i;
110  int16_t *buf_out;
111  float e = 1.0;
112  float scaling;
113 
114  if (avpkt->size) {
115  int dbov = -avpkt->data[0];
116  p->target_energy = 1081109975 * ff_exp10(dbov / 10.0) * 0.75;
117  memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef));
118  for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) {
119  p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0;
120  }
121  }
122 
123  if (p->inited) {
124  p->energy = p->energy / 2 + p->target_energy / 2;
125  for (i = 0; i < p->order; i++)
126  p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i];
127  } else {
128  p->energy = p->target_energy;
129  memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef));
130  p->inited = 1;
131  }
133 
134  for (i = 0; i < p->order; i++)
135  e *= 1.0 - p->refl_coef[i]*p->refl_coef[i];
136 
137  scaling = sqrt(e * p->energy / 1081109975);
138  for (i = 0; i < avctx->frame_size; i++) {
139  int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000;
140  p->excitation[i] = scaling * r;
141  }
143  p->excitation, avctx->frame_size, p->order);
144 
145  frame->nb_samples = avctx->frame_size;
146  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
147  return ret;
148  buf_out = (int16_t *)frame->data[0];
149  for (i = 0; i < avctx->frame_size; i++)
150  buf_out[i] = p->filter_out[i + p->order];
151  memcpy(p->filter_out, p->filter_out + avctx->frame_size,
152  p->order * sizeof(*p->filter_out));
153 
154  *got_frame_ptr = 1;
155 
156  return buf_size;
157 }
158 
160  .name = "comfortnoise",
161  .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
162  .type = AVMEDIA_TYPE_AUDIO,
164  .priv_data_size = sizeof(CNGContext),
168  .close = cng_decode_close,
169  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
171  .capabilities = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_DR1,
172 };
Definition: lfg.h:25
void ff_celp_lp_synthesis_filterf(float *out, const float *filter_coeffs, const float *in, int buffer_length, int filter_length)
LP synthesis filter.
Definition: celp_filters.c:84
This structure describes decoded (raw) audio or video data.
Definition: frame.h:180
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
static void flush(AVCodecContext *avctx)
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
static int cng_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
Definition: cngdec.c:103
int size
Definition: avcodec.h:1575
AVCodec.
Definition: avcodec.h:3531
AVCodec ff_comfortnoise_decoder
Definition: cngdec.c:159
#define AV_CODEC_CAP_DELAY
Encoder or decoder requires flushing with NULL input at the end in order to give the complete and cor...
Definition: avcodec.h:975
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2408
#define av_cold
Definition: attributes.h:82
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1574
unsigned m
Definition: audioconvert.c:187
int inited
Definition: cngdec.c:36
static av_always_inline double ff_exp10(double x)
Compute 10^x for floating point values.
Definition: ffmath.h:42
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
const char * r
Definition: vf_curves.c:107
const char * name
Name of the codec implementation.
Definition: avcodec.h:3538
float * lpc_coef
Definition: cngdec.c:33
float * filter_out
Definition: cngdec.c:37
#define FFMIN(a, b)
Definition: common.h:96
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:2420
static void cng_decode_flush(AVCodecContext *avctx)
Definition: cngdec.c:97
Libavcodec external API header.
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
int sample_rate
samples per second
Definition: avcodec.h:2400
main external API structure.
Definition: avcodec.h:1639
int order
Definition: cngdec.c:34
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:928
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:38
void * buf
Definition: avisynth_c.h:553
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:30
float * refl_coef
Definition: cngdec.c:32
float * target_refl_coef
Definition: cngdec.c:32
static void make_lpc_coefs(float *lpc, const float *refl, int order)
Definition: cngdec.c:80
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:194
static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
Definition: ccaption_dec.c:722
internal math functions header
common internal api header.
common internal and external API header
signed 16 bits
Definition: samplefmt.h:61
void * priv_data
Definition: avcodec.h:1681
static av_cold int cng_decode_close(AVCodecContext *avctx)
Definition: cngdec.c:42
AVLFG lfg
Definition: cngdec.c:39
int channels
number of audio channels
Definition: avcodec.h:2401
static void * av_mallocz_array(size_t nmemb, size_t size)
Definition: mem.h:229
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
int target_energy
Definition: cngdec.c:35
#define av_freep(p)
float * excitation
Definition: cngdec.c:38
#define FFSWAP(type, a, b)
Definition: common.h:99
int energy
Definition: cngdec.c:35
This structure stores compressed data.
Definition: avcodec.h:1551
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:237
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:950
static av_cold int cng_decode_init(AVCodecContext *avctx)
Definition: cngdec.c:53
for(j=16;j >0;--j)