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116 lines
3.5 KiB
116 lines
3.5 KiB
/* |
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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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.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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};
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