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libavcodec
cngenc.c
Go to the documentation of this file.
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/*
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* RFC 3389 comfort noise generator
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* Copyright (c) 2012 Martin Storsjo
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <math.h>
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#include "
libavutil/common.h
"
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#include "
avcodec.h
"
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#include "
internal.h
"
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#include "
lpc.h
"
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typedef
struct
CNGContext
{
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LPCContext
lpc
;
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int
order
;
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int32_t
*
samples32
;
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double
*
ref_coef
;
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}
CNGContext
;
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static
av_cold
int
cng_encode_close
(
AVCodecContext
*avctx)
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{
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CNGContext
*p = avctx->
priv_data
;
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ff_lpc_end
(&p->
lpc
);
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av_free
(p->
samples32
);
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av_free
(p->
ref_coef
);
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return
0;
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}
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static
av_cold
int
cng_encode_init
(
AVCodecContext
*avctx)
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{
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CNGContext
*p = avctx->
priv_data
;
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int
ret
;
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if
(avctx->
channels
!= 1) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Only mono supported\n"
);
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return
AVERROR
(EINVAL);
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}
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avctx->
frame_size
= 640;
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p->
order
= 10;
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if
((ret =
ff_lpc_init
(&p->
lpc
, avctx->
frame_size
, p->
order
,
FF_LPC_TYPE_LEVINSON
)) < 0)
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return
ret
;
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p->
samples32
=
av_malloc
(avctx->
frame_size
*
sizeof
(*p->
samples32
));
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p->
ref_coef
=
av_malloc
(p->
order
*
sizeof
(*p->
ref_coef
));
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if
(!p->
samples32
|| !p->
ref_coef
) {
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cng_encode_close
(avctx);
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return
AVERROR
(ENOMEM);
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}
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return
0;
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}
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static
int
cng_encode_frame
(
AVCodecContext
*avctx,
AVPacket
*avpkt,
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const
AVFrame
*
frame
,
int
*got_packet_ptr)
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{
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CNGContext
*p = avctx->
priv_data
;
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int
ret
, i;
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double
energy = 0;
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int
qdbov;
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int16_t *samples = (int16_t*) frame->
data
[0];
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if
((ret =
ff_alloc_packet
(avpkt, 1 + p->
order
))) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Error getting output packet\n"
);
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return
ret
;
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}
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for
(i = 0; i < frame->
nb_samples
; i++) {
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p->
samples32
[i] = samples[i];
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energy += samples[i] * samples[i];
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}
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energy /= frame->
nb_samples
;
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if
(energy > 0) {
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double
dbov = 10 * log10(energy / 1081109975);
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qdbov = av_clip(-floor(dbov), 0, 127);
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}
else
{
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qdbov = 127;
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}
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ret =
ff_lpc_calc_ref_coefs
(&p->
lpc
, p->
samples32
, p->
order
, p->
ref_coef
);
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avpkt->
data
[0] = qdbov;
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for
(i = 0; i < p->
order
; i++)
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avpkt->
data
[1 + i] = p->
ref_coef
[i] * 127 + 127;
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*got_packet_ptr = 1;
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avpkt->
size
= 1 + p->
order
;
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return
0;
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}
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AVCodec
ff_comfortnoise_encoder
= {
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.
name
=
"comfortnoise"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"RFC 3389 comfort noise generator"
),
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.type =
AVMEDIA_TYPE_AUDIO
,
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.id =
AV_CODEC_ID_COMFORT_NOISE
,
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.priv_data_size =
sizeof
(
CNGContext
),
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.
init
=
cng_encode_init
,
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.encode2 =
cng_encode_frame
,
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.
close
=
cng_encode_close
,
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.
sample_fmts
= (
const
enum
AVSampleFormat
[]){
AV_SAMPLE_FMT_S16
,
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AV_SAMPLE_FMT_NONE
},
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};
Generated on Sun Mar 23 2014 23:49:52 for FFmpeg by
1.8.2