/* * 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 "libavutil/ffmath.h"#include "libavutil/mem.h"#include "avcodec.h"#include "celp_filters.h"#include "codec_internal.h"#include "decode.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_freep(&p->refl_coef);    av_freep(&p->target_refl_coef);    av_freep(&p->lpc_coef);    av_freep(&p->filter_out);    av_freep(&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;    av_channel_layout_uninit(&avctx->ch_layout);    avctx->ch_layout   = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;    avctx->sample_rate = 8000;     p->order            = 12;    avctx->frame_size   = 640;    p->refl_coef        = av_calloc(p->order, sizeof(*p->refl_coef));    p->target_refl_coef = av_calloc(p->order, sizeof(*p->target_refl_coef));    p->lpc_coef         = av_calloc(p->order, sizeof(*p->lpc_coef));    p->filter_out       = av_calloc(avctx->frame_size + p->order,                                     sizeof(*p->filter_out));    p->excitation       = av_calloc(avctx->frame_size, sizeof(*p->excitation));    if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef ||        !p->filter_out || !p->excitation) {        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, AVFrame *frame,                            int *got_frame_ptr, AVPacket *avpkt){    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 * ff_exp10(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 (avctx->internal->skip_samples > 10 * avctx->frame_size) {        avctx->internal->skip_samples = 0;        return AVERROR_INVALIDDATA;    }     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] = av_clip_int16(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;} const FFCodec ff_comfortnoise_decoder = {    .p.name         = "comfortnoise",    CODEC_LONG_NAME("RFC 3389 comfort noise generator"),    .p.type         = AVMEDIA_TYPE_AUDIO,    .p.id           = AV_CODEC_ID_COMFORT_NOISE,    .priv_data_size = sizeof(CNGContext),    .init           = cng_decode_init,    FF_CODEC_DECODE_CB(cng_decode_frame),    .flush          = cng_decode_flush,    .close          = cng_decode_close,    .p.sample_fmts  = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,                                                     AV_SAMPLE_FMT_NONE },    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,};