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