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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 "libavutil/intreadwrite.h"
27 #include "avcodec.h"
28 #include "celp_filters.h"
29 #include "internal.h"
30 #include "libavutil/lfg.h"
31 
32 typedef struct CNGContext {
34  float *lpc_coef;
35  int order;
37  int inited;
38  float *filter_out;
39  float *excitation;
41 } CNGContext;
42 
44 {
45  CNGContext *p = avctx->priv_data;
46  av_freep(&p->refl_coef);
48  av_freep(&p->lpc_coef);
49  av_freep(&p->filter_out);
50  av_freep(&p->excitation);
51  return 0;
52 }
53 
55 {
56  CNGContext *p = avctx->priv_data;
57 
59  avctx->channels = 1;
60  avctx->sample_rate = 8000;
61 
62  p->order = 12;
63  avctx->frame_size = 640;
64  p->refl_coef = av_mallocz_array(p->order, sizeof(*p->refl_coef));
66  p->lpc_coef = av_mallocz_array(p->order, sizeof(*p->lpc_coef));
68  sizeof(*p->filter_out));
69  p->excitation = av_mallocz_array(avctx->frame_size, sizeof(*p->excitation));
70  if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef ||
71  !p->filter_out || !p->excitation) {
72  cng_decode_close(avctx);
73  return AVERROR(ENOMEM);
74  }
75 
76  av_lfg_init(&p->lfg, 0);
77 
78  return 0;
79 }
80 
81 static void make_lpc_coefs(float *lpc, const float *refl, int order)
82 {
83  float buf[100];
84  float *next, *cur;
85  int m, i;
86  next = buf;
87  cur = lpc;
88  for (m = 0; m < order; m++) {
89  next[m] = refl[m];
90  for (i = 0; i < m; i++)
91  next[i] = cur[i] + refl[m] * cur[m - i - 1];
92  FFSWAP(float*, next, cur);
93  }
94  if (cur != lpc)
95  memcpy(lpc, cur, sizeof(*lpc) * order);
96 }
97 
98 static void cng_decode_flush(AVCodecContext *avctx)
99 {
100  CNGContext *p = avctx->priv_data;
101  p->inited = 0;
102 }
103 
104 static int cng_decode_frame(AVCodecContext *avctx, void *data,
105  int *got_frame_ptr, AVPacket *avpkt)
106 {
107  AVFrame *frame = data;
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  }
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  }
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] = 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 
166  .name = "comfortnoise",
167  .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
168  .type = AVMEDIA_TYPE_AUDIO,
170  .priv_data_size = sizeof(CNGContext),
174  .close = cng_decode_close,
175  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
177  .capabilities = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_DR1,
178 };
Definition: lfg.h:27
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
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:201
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:104
int size
Definition: avcodec.h:1673
AVCodec.
Definition: avcodec.h:3730
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:42
AVCodec ff_comfortnoise_decoder
Definition: cngdec.c:165
#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:1027
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2524
#define av_cold
Definition: attributes.h:82
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1672
int inited
Definition: cngdec.c:37
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:179
const char * r
Definition: vf_curves.c:111
const char * name
Name of the codec implementation.
Definition: avcodec.h:3737
static void * av_mallocz_array(size_t nmemb, size_t size)
Definition: mem.h:229
float * lpc_coef
Definition: cngdec.c:34
float * filter_out
Definition: cngdec.c:38
#define FFMIN(a, b)
Definition: common.h:96
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:2536
static void cng_decode_flush(AVCodecContext *avctx)
Definition: cngdec.c:98
Libavcodec external API header.
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
int sample_rate
samples per second
Definition: avcodec.h:2516
main external API structure.
Definition: avcodec.h:1754
int order
Definition: cngdec.c:35
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1663
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:47
void * buf
Definition: avisynth_c.h:690
int skip_samples
Number of audio samples to skip at the start of the next decoded frame.
Definition: internal.h:187
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
float * refl_coef
Definition: cngdec.c:33
float * target_refl_coef
Definition: cngdec.c:33
static void make_lpc_coefs(float *lpc, const float *refl, int order)
Definition: cngdec.c:81
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:215
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:1796
static av_cold int cng_decode_close(AVCodecContext *avctx)
Definition: cngdec.c:43
AVLFG lfg
Definition: cngdec.c:40
int channels
number of audio channels
Definition: avcodec.h:2517
struct AVCodecInternal * internal
Private context used for internal data.
Definition: avcodec.h:1804
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
int target_energy
Definition: cngdec.c:36
#define av_freep(p)
float * excitation
Definition: cngdec.c:39
#define FFSWAP(type, a, b)
Definition: common.h:99
int energy
Definition: cngdec.c:36
This structure stores compressed data.
Definition: avcodec.h:1649
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:267
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:1002
static av_cold int cng_decode_init(AVCodecContext *avctx)
Definition: cngdec.c:54
for(j=16;j >0;--j)