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 "codec_internal.h"
30 #include "decode.h"
31 #include "internal.h"
32 #include "libavutil/lfg.h"
33 
34 typedef struct CNGContext {
36  float *lpc_coef;
37  int order;
39  int inited;
40  float *filter_out;
41  float *excitation;
43 } CNGContext;
44 
46 {
47  CNGContext *p = avctx->priv_data;
48  av_freep(&p->refl_coef);
50  av_freep(&p->lpc_coef);
51  av_freep(&p->filter_out);
52  av_freep(&p->excitation);
53  return 0;
54 }
55 
57 {
58  CNGContext *p = avctx->priv_data;
59 
63  avctx->sample_rate = 8000;
64 
65  p->order = 12;
66  avctx->frame_size = 640;
67  p->refl_coef = av_calloc(p->order, sizeof(*p->refl_coef));
68  p->target_refl_coef = av_calloc(p->order, sizeof(*p->target_refl_coef));
69  p->lpc_coef = av_calloc(p->order, sizeof(*p->lpc_coef));
70  p->filter_out = av_calloc(avctx->frame_size + p->order,
71  sizeof(*p->filter_out));
72  p->excitation = av_calloc(avctx->frame_size, sizeof(*p->excitation));
73  if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef ||
74  !p->filter_out || !p->excitation) {
75  return AVERROR(ENOMEM);
76  }
77 
78  av_lfg_init(&p->lfg, 0);
79 
80  return 0;
81 }
82 
83 static void make_lpc_coefs(float *lpc, const float *refl, int order)
84 {
85  float buf[100];
86  float *next, *cur;
87  int m, i;
88  next = buf;
89  cur = lpc;
90  for (m = 0; m < order; m++) {
91  next[m] = refl[m];
92  for (i = 0; i < m; i++)
93  next[i] = cur[i] + refl[m] * cur[m - i - 1];
94  FFSWAP(float*, next, cur);
95  }
96  if (cur != lpc)
97  memcpy(lpc, cur, sizeof(*lpc) * order);
98 }
99 
100 static void cng_decode_flush(AVCodecContext *avctx)
101 {
102  CNGContext *p = avctx->priv_data;
103  p->inited = 0;
104 }
105 
107  int *got_frame_ptr, AVPacket *avpkt)
108 {
109  CNGContext *p = avctx->priv_data;
110  int buf_size = avpkt->size;
111  int ret, i;
112  int16_t *buf_out;
113  float e = 1.0;
114  float scaling;
115 
116  if (avpkt->size) {
117  int dbov = -avpkt->data[0];
118  p->target_energy = 1081109975 * ff_exp10(dbov / 10.0) * 0.75;
119  memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef));
120  for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) {
121  p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0;
122  }
123  }
124 
125  if (avctx->internal->skip_samples > 10 * avctx->frame_size) {
126  avctx->internal->skip_samples = 0;
127  return AVERROR_INVALIDDATA;
128  }
129 
130  if (p->inited) {
131  p->energy = p->energy / 2 + p->target_energy / 2;
132  for (i = 0; i < p->order; i++)
133  p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i];
134  } else {
135  p->energy = p->target_energy;
136  memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef));
137  p->inited = 1;
138  }
140 
141  for (i = 0; i < p->order; i++)
142  e *= 1.0 - p->refl_coef[i]*p->refl_coef[i];
143 
144  scaling = sqrt(e * p->energy / 1081109975);
145  for (i = 0; i < avctx->frame_size; i++) {
146  int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000;
147  p->excitation[i] = scaling * r;
148  }
150  p->excitation, avctx->frame_size, p->order);
151 
152  frame->nb_samples = avctx->frame_size;
153  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
154  return ret;
155  buf_out = (int16_t *)frame->data[0];
156  for (i = 0; i < avctx->frame_size; i++)
157  buf_out[i] = av_clip_int16(p->filter_out[i + p->order]);
158  memcpy(p->filter_out, p->filter_out + avctx->frame_size,
159  p->order * sizeof(*p->filter_out));
160 
161  *got_frame_ptr = 1;
162 
163  return buf_size;
164 }
165 
167  .p.name = "comfortnoise",
168  CODEC_LONG_NAME("RFC 3389 comfort noise generator"),
169  .p.type = AVMEDIA_TYPE_AUDIO,
171  .priv_data_size = sizeof(CNGContext),
174  .flush = cng_decode_flush,
175  .close = cng_decode_close,
176  .p.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
178  .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
179  .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
180 };
AVCodecContext::frame_size
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:1068
CNGContext::target_energy
int target_energy
Definition: cngdec.c:38
ff_exp10
static av_always_inline double ff_exp10(double x)
Compute 10^x for floating point values.
Definition: ffmath.h:42
FF_CODEC_CAP_INIT_CLEANUP
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: codec_internal.h:42
r
const char * r
Definition: vf_curves.c:126
AVERROR
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
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1040
av_lfg_init
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
AVCodecInternal::skip_samples
int skip_samples
Number of audio samples to skip at the start of the next decoded frame.
Definition: internal.h:132
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:330
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:374
make_lpc_coefs
static void make_lpc_coefs(float *lpc, const float *refl, int order)
Definition: cngdec.c:83
FFCodec
Definition: codec_internal.h:127
CNGContext::lpc_coef
float * lpc_coef
Definition: cngdec.c:36
ff_celp_lp_synthesis_filterf
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:85
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:2092
CNGContext::inited
int inited
Definition: cngdec.c:39
av_cold
#define av_cold
Definition: attributes.h:90
CNGContext::excitation
float * excitation
Definition: cngdec.c:41
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:306
intreadwrite.h
av_lfg_get
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:53
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
lfg.h
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts_bsf.c:365
cng_decode_frame
static int cng_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)
Definition: cngdec.c:106
ff_comfortnoise_decoder
const FFCodec ff_comfortnoise_decoder
Definition: cngdec.c:166
decode.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
av_clip_int16
#define av_clip_int16
Definition: common.h:110
AVCodecContext::internal
struct AVCodecInternal * internal
Private context used for internal data.
Definition: avcodec.h:466
CNGContext
Definition: cngdec.c:34
CNGContext::filter_out
float * filter_out
Definition: cngdec.c:40
celp_filters.h
cng_decode_close
static av_cold int cng_decode_close(AVCodecContext *avctx)
Definition: cngdec.c:45
cng_decode_flush
static void cng_decode_flush(AVCodecContext *avctx)
Definition: cngdec.c:100
CNGContext::refl_coef
float * refl_coef
Definition: cngdec.c:35
AV_CODEC_CAP_CHANNEL_CONF
#define AV_CODEC_CAP_CHANNEL_CONF
Codec should fill in channel configuration and samplerate instead of container.
Definition: codec.h:109
AVLFG
Context structure for the Lagged Fibonacci PRNG.
Definition: lfg.h:33
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1461
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:375
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:301
codec_internal.h
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1056
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
AV_CODEC_ID_COMFORT_NOISE
@ AV_CODEC_ID_COMFORT_NOISE
Definition: codec_id.h:498
CNGContext::energy
int energy
Definition: cngdec.c:38
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
CNGContext::lfg
AVLFG lfg
Definition: cngdec.c:42
common.h
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:58
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:211
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:272
avcodec.h
CNGContext::order
int order
Definition: cngdec.c:37
ret
ret
Definition: filter_design.txt:187
FFSWAP
#define FFSWAP(type, a, b)
Definition: macros.h:52
frame
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
Definition: filter_design.txt:264
AVCodecContext
main external API structure.
Definition: avcodec.h:431
av_channel_layout_uninit
void av_channel_layout_uninit(AVChannelLayout *channel_layout)
Free any allocated data in the channel layout and reset the channel count to 0.
Definition: channel_layout.c:632
cng_decode_init
static av_cold int cng_decode_init(AVCodecContext *avctx)
Definition: cngdec.c:56
ffmath.h
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:368
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:458
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
CNGContext::target_refl_coef
float * target_refl_coef
Definition: cngdec.c:35