FFmpeg
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  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 (avctx->internal->skip_samples > 10 * avctx->frame_size) {
124  avctx->internal->skip_samples = 0;
125  return AVERROR_INVALIDDATA;
126  }
127 
128  if (p->inited) {
129  p->energy = p->energy / 2 + p->target_energy / 2;
130  for (i = 0; i < p->order; i++)
131  p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i];
132  } else {
133  p->energy = p->target_energy;
134  memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef));
135  p->inited = 1;
136  }
138 
139  for (i = 0; i < p->order; i++)
140  e *= 1.0 - p->refl_coef[i]*p->refl_coef[i];
141 
142  scaling = sqrt(e * p->energy / 1081109975);
143  for (i = 0; i < avctx->frame_size; i++) {
144  int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000;
145  p->excitation[i] = scaling * r;
146  }
148  p->excitation, avctx->frame_size, p->order);
149 
150  frame->nb_samples = avctx->frame_size;
151  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
152  return ret;
153  buf_out = (int16_t *)frame->data[0];
154  for (i = 0; i < avctx->frame_size; i++)
155  buf_out[i] = av_clip_int16(p->filter_out[i + p->order]);
156  memcpy(p->filter_out, p->filter_out + avctx->frame_size,
157  p->order * sizeof(*p->filter_out));
158 
159  *got_frame_ptr = 1;
160 
161  return buf_size;
162 }
163 
165  .name = "comfortnoise",
166  .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
167  .type = AVMEDIA_TYPE_AUDIO,
169  .priv_data_size = sizeof(CNGContext),
173  .close = cng_decode_close,
174  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
176  .capabilities = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_DR1,
177  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE |
179 };
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:48
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:295
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
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:1481
AVCodec.
Definition: avcodec.h:3492
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
AVCodec ff_comfortnoise_decoder
Definition: cngdec.c:164
#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:1009
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:40
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2236
#define av_cold
Definition: attributes.h:82
uint8_t * data
Definition: avcodec.h:1480
int inited
Definition: cngdec.c:37
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
static av_always_inline double ff_exp10(double x)
Compute 10^x for floating point values.
Definition: ffmath.h:42
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
const char * r
Definition: vf_curves.c:114
const char * name
Name of the codec implementation.
Definition: avcodec.h:3499
float * lpc_coef
Definition: cngdec.c:34
float * filter_out
Definition: cngdec.c:38
#define FFMIN(a, b)
Definition: common.h:96
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:2248
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:2228
LPCContext lpc
Definition: cngenc.c:30
main external API structure.
Definition: avcodec.h:1568
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:1968
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:766
int skip_samples
Number of audio samples to skip at the start of the next decoded frame.
Definition: internal.h:185
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:80
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
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:1595
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:2229
struct AVCodecInternal * internal
Private context used for internal data.
Definition: avcodec.h:1603
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
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1457
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:361
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:984
static av_cold int cng_decode_init(AVCodecContext *avctx)
Definition: cngdec.c:54
for(j=16;j >0;--j)
void * av_mallocz_array(size_t nmemb, size_t size)
Definition: mem.c:191