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cngenc.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 "avcodec.h"
26 #include "internal.h"
27 #include "lpc.h"
28 
29 typedef struct CNGContext {
31  int order;
33  double *ref_coef;
34 } CNGContext;
35 
37 {
38  CNGContext *p = avctx->priv_data;
39  ff_lpc_end(&p->lpc);
40  av_free(p->samples32);
41  av_free(p->ref_coef);
42  return 0;
43 }
44 
46 {
47  CNGContext *p = avctx->priv_data;
48  int ret;
49 
50  if (avctx->channels != 1) {
51  av_log(avctx, AV_LOG_ERROR, "Only mono supported\n");
52  return AVERROR(EINVAL);
53  }
54 
55  avctx->frame_size = 640;
56  p->order = 10;
57  if ((ret = ff_lpc_init(&p->lpc, avctx->frame_size, p->order, FF_LPC_TYPE_LEVINSON)) < 0)
58  return ret;
59  p->samples32 = av_malloc_array(avctx->frame_size, sizeof(*p->samples32));
60  p->ref_coef = av_malloc_array(p->order, sizeof(*p->ref_coef));
61  if (!p->samples32 || !p->ref_coef) {
62  cng_encode_close(avctx);
63  return AVERROR(ENOMEM);
64  }
65 
66  return 0;
67 }
68 
69 static int cng_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
70  const AVFrame *frame, int *got_packet_ptr)
71 {
72  CNGContext *p = avctx->priv_data;
73  int ret, i;
74  double energy = 0;
75  int qdbov;
76  int16_t *samples = (int16_t*) frame->data[0];
77 
78  if ((ret = ff_alloc_packet(avpkt, 1 + p->order))) {
79  av_log(avctx, AV_LOG_ERROR, "Error getting output packet\n");
80  return ret;
81  }
82 
83  for (i = 0; i < frame->nb_samples; i++) {
84  p->samples32[i] = samples[i];
85  energy += samples[i] * samples[i];
86  }
87  energy /= frame->nb_samples;
88  if (energy > 0) {
89  double dbov = 10 * log10(energy / 1081109975);
90  qdbov = av_clip_uintp2(-floor(dbov), 7);
91  } else {
92  qdbov = 127;
93  }
94  ret = ff_lpc_calc_ref_coefs(&p->lpc, p->samples32, p->order, p->ref_coef);
95  avpkt->data[0] = qdbov;
96  for (i = 0; i < p->order; i++)
97  avpkt->data[1 + i] = p->ref_coef[i] * 127 + 127;
98 
99  *got_packet_ptr = 1;
100  avpkt->size = 1 + p->order;
101 
102  return 0;
103 }
104 
106  .name = "comfortnoise",
107  .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
108  .type = AVMEDIA_TYPE_AUDIO,
110  .priv_data_size = sizeof(CNGContext),
112  .encode2 = cng_encode_frame,
113  .close = cng_encode_close,
114  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
116 };
This structure describes decoded (raw) audio or video data.
Definition: frame.h:171
Definition: lpc.h:52
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int size
Definition: avcodec.h:1423
AVCodec.
Definition: avcodec.h:3473
if()
Definition: avfilter.c:975
#define av_cold
Definition: attributes.h:74
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1422
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
Definition: lpc.c:158
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#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:175
const char * name
Name of the codec implementation.
Definition: avcodec.h:3480
Libavcodec external API header.
av_cold void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
Definition: lpc.c:296
ret
Definition: avfilter.c:974
int32_t
AVCodec ff_comfortnoise_encoder
Definition: cngenc.c:105
int32_t * samples32
Definition: cngenc.c:32
static av_cold int cng_encode_close(AVCodecContext *avctx)
Definition: cngenc.c:36
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:2281
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:59
LPCContext lpc
Definition: cngenc.c:30
main external API structure.
Definition: avcodec.h:1501
int order
Definition: cngdec.c:33
Levinson-Durbin recursion.
Definition: lpc.h:47
double * ref_coef
Definition: cngenc.c:33
av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order, enum FFLPCType lpc_type)
Initialize LPCContext.
Definition: lpc.c:274
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:182
static int cng_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
Definition: cngenc.c:69
common internal api header.
common internal and external API header
signed 16 bits
Definition: samplefmt.h:62
void * priv_data
Definition: avcodec.h:1543
#define av_free(p)
int channels
number of audio channels
Definition: avcodec.h:2262
attribute_deprecated int ff_alloc_packet(AVPacket *avpkt, int size)
Definition: utils.c:1836
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
static av_cold int cng_encode_init(AVCodecContext *avctx)
Definition: cngenc.c:45
#define av_malloc_array(a, b)
This structure stores compressed data.
Definition: avcodec.h:1399
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:225