/* * The simplest AC-3 encoder * Copyright (c) 2000 Fabrice Bellard * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com> * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de> * * 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 */ /** * @file * floating-point AC-3 encoder. */ #define AC3ENC_FLOAT 1#include "audiodsp.h"#include "ac3enc.h"#include "codec_internal.h"#include "eac3enc.h"#include "kbdwin.h"  /* * Scale MDCT coefficients from float to 24-bit fixed-point. */static void scale_coefficients(AC3EncodeContext *s){    int chan_size = AC3_MAX_COEFS * s->num_blocks;    int cpl       = s->cpl_on;    s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),                               s->mdct_coef_buffer  + (chan_size * !cpl),                               chan_size * (s->channels + cpl));}  /* * Clip MDCT coefficients to allowable range. */static void clip_coefficients(AudioDSPContext *adsp, float *coef,                              unsigned int len){    adsp->vector_clipf(coef, coef, len, COEF_MIN, COEF_MAX);}  /* * Calculate a single coupling coordinate. */static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl){    float coord = 0.125;    if (energy_cpl > 0)        coord *= sqrtf(energy_ch / energy_cpl);    return FFMIN(coord, COEF_MAX);} static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],                                 const float *coef0, const float *coef1,                                 int len){    s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);} #include "ac3enc_template.c" /** * Initialize MDCT tables. * * @param s  AC-3 encoder private context * @return   0 on success, negative error code on failure */static av_cold int ac3_float_mdct_init(AC3EncodeContext *s){    const float scale = -2.0 / AC3_WINDOW_SIZE;    float *window = av_malloc_array(AC3_BLOCK_SIZE, sizeof(*window));    if (!window) {        av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");        return AVERROR(ENOMEM);    }     ff_kbd_window_init(window, 5.0, AC3_BLOCK_SIZE);    s->mdct_window = window;     return av_tx_init(&s->tx, &s->tx_fn, AV_TX_FLOAT_MDCT, 0,                      AC3_BLOCK_SIZE, &scale, 0);}  av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx){    AC3EncodeContext *s = avctx->priv_data;    s->mdct_init               = ac3_float_mdct_init;    s->allocate_sample_buffers = allocate_sample_buffers;    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);    if (!s->fdsp)        return AVERROR(ENOMEM);    return ff_ac3_encode_init(avctx);} const FFCodec ff_ac3_encoder = {    .p.name          = "ac3",    CODEC_LONG_NAME("ATSC A/52A (AC-3)"),    .p.type          = AVMEDIA_TYPE_AUDIO,    .p.id            = AV_CODEC_ID_AC3,    .p.capabilities  = AV_CODEC_CAP_DR1,    .priv_data_size  = sizeof(AC3EncodeContext),    .init            = ff_ac3_float_encode_init,    FF_CODEC_ENCODE_CB(ff_ac3_float_encode_frame),    .close           = ff_ac3_encode_close,    .p.sample_fmts   = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,                                                      AV_SAMPLE_FMT_NONE },    .p.priv_class    = &ff_ac3enc_class,    .p.supported_samplerates = ff_ac3_sample_rate_tab,    CODEC_OLD_CHANNEL_LAYOUTS_ARRAY(ff_ac3_channel_layouts)    .p.ch_layouts    = ff_ac3_ch_layouts,    .defaults        = ff_ac3_enc_defaults,    .caps_internal   = FF_CODEC_CAP_INIT_CLEANUP,};