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  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] = av_clip_int16(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:268
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:104
int size
Definition: avcodec.h:1478
AVCodec.
Definition: avcodec.h:3477
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:1006
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2229
#define av_cold
Definition: attributes.h:82
uint8_t * data
Definition: avcodec.h:1477
int inited
Definition: cngdec.c:37
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:260
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:3484
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:2241
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:2221
LPCContext lpc
Definition: cngenc.c:30
main external API structure.
Definition: avcodec.h:1565
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:1964
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:81
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:282
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:1592
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:2222
struct AVCodecInternal * internal
Private context used for internal data.
Definition: avcodec.h:1600
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:1454
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:334
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:981
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