/* * 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 "celp_filters.h" #include "internal.h" #include "libavutil/lfg.h" typedef struct CNGContext { float *refl_coef, *target_refl_coef; float *lpc_coef; int order; int energy, target_energy; int inited; float *filter_out; float *excitation; AVLFG lfg; } CNGContext; static av_cold int cng_decode_close(AVCodecContext *avctx) { CNGContext *p = avctx->priv_data; av_free(p->refl_coef); av_free(p->target_refl_coef); av_free(p->lpc_coef); av_free(p->filter_out); av_free(p->excitation); return 0; } static av_cold int cng_decode_init(AVCodecContext *avctx) { CNGContext *p = avctx->priv_data; avctx->sample_fmt = AV_SAMPLE_FMT_S16; avctx->channels = 1; avctx->sample_rate = 8000; p->order = 12; avctx->frame_size = 640; p->refl_coef = av_mallocz(p->order * sizeof(*p->refl_coef)); p->target_refl_coef = av_mallocz(p->order * sizeof(*p->target_refl_coef)); p->lpc_coef = av_mallocz(p->order * sizeof(*p->lpc_coef)); p->filter_out = av_mallocz((avctx->frame_size + p->order) * sizeof(*p->filter_out)); p->excitation = av_mallocz(avctx->frame_size * sizeof(*p->excitation)); if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef || !p->filter_out || !p->excitation) { cng_decode_close(avctx); return AVERROR(ENOMEM); } av_lfg_init(&p->lfg, 0); return 0; } static void make_lpc_coefs(float *lpc, const float *refl, int order) { float buf[100]; float *next, *cur; int m, i; next = buf; cur = lpc; for (m = 0; m < order; m++) { next[m] = refl[m]; for (i = 0; i < m; i++) next[i] = cur[i] + refl[m] * cur[m - i - 1]; FFSWAP(float*, next, cur); } if (cur != lpc) memcpy(lpc, cur, sizeof(*lpc) * order); } static void cng_decode_flush(AVCodecContext *avctx) { CNGContext *p = avctx->priv_data; p->inited = 0; } static int cng_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt) { AVFrame *frame = data; CNGContext *p = avctx->priv_data; int buf_size = avpkt->size; int ret, i; int16_t *buf_out; float e = 1.0; float scaling; if (avpkt->size) { int dbov = -avpkt->data[0]; p->target_energy = 1081109975 * pow(10, dbov / 10.0) * 0.75; memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef)); for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) { p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0; } } if (p->inited) { p->energy = p->energy / 2 + p->target_energy / 2; for (i = 0; i < p->order; i++) p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i]; } else { p->energy = p->target_energy; memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef)); p->inited = 1; } make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order); for (i = 0; i < p->order; i++) e *= 1.0 - p->refl_coef[i]*p->refl_coef[i]; scaling = sqrt(e * p->energy / 1081109975); for (i = 0; i < avctx->frame_size; i++) { int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000; p->excitation[i] = scaling * r; } ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef, p->excitation, avctx->frame_size, p->order); frame->nb_samples = avctx->frame_size; if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) return ret; buf_out = (int16_t *)frame->data[0]; for (i = 0; i < avctx->frame_size; i++) buf_out[i] = p->filter_out[i + p->order]; memcpy(p->filter_out, p->filter_out + avctx->frame_size, p->order * sizeof(*p->filter_out)); *got_frame_ptr = 1; return buf_size; } AVCodec ff_comfortnoise_decoder = { .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_decode_init, .decode = cng_decode_frame, .flush = cng_decode_flush, .close = cng_decode_close, .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE }, .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, };