/* * 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_array(avctx->frame_size, sizeof(*p->samples32)); p->ref_coef = av_malloc_array(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", .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), .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, .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE }, };