FFmpeg
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_packet2(avctx, avpkt, 1 + p->order, 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  }
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  av_assert1(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:295
Definition: lpc.h:52
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int size
Definition: avcodec.h:1478
AVCodec.
Definition: avcodec.h:3481
int ff_alloc_packet2(AVCodecContext *avctx, AVPacket *avpkt, int64_t size, int64_t min_size)
Check AVPacket size and/or allocate data.
Definition: encode.c:32
#define av_cold
Definition: attributes.h:82
uint8_t * data
Definition: avcodec.h:1477
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
Definition: lpc.c:159
#define av_log(a,...)
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
const char * name
Name of the codec implementation.
Definition: avcodec.h:3488
av_cold void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
Definition: lpc.c:322
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
int32_t
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
AVCodec ff_comfortnoise_encoder
Definition: cngenc.c:105
int32_t * samples32
Definition: cngenc.c:32
if(ret)
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:2245
Libavcodec external API header.
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
LPCContext lpc
Definition: cngenc.c:30
main external API structure.
Definition: avcodec.h:1565
int order
Definition: cngdec.c:35
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:300
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
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:61
void * priv_data
Definition: avcodec.h:1592
#define av_free(p)
int channels
number of audio channels
Definition: avcodec.h:2226
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
Filter the word “frame” indicates either a video frame or a group of audio samples
static av_cold int cng_encode_init(AVCodecContext *avctx)
Definition: cngenc.c:45
#define av_malloc_array(a, b)
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:361