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117 lines
3.5 KiB
C
117 lines
3.5 KiB
C
/*
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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 Libav.
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*
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* Libav 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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* Libav 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 Libav; 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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.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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.long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"),
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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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};
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