/* * 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 CONFIG_AC3ENC_FLOAT 1#include "internal.h"#include "audiodsp.h"#include "ac3enc.h"#include "eac3enc.h"#include "kbdwin.h"  #define AC3ENC_TYPE AC3ENC_TYPE_AC3#include "ac3enc_opts_template.c"static const AVClass ac3enc_class = {    .class_name = "AC-3 Encoder",    .item_name  = av_default_item_name,    .option     = ac3_options,    .version    = LIBAVUTIL_VERSION_INT,}; #include "ac3enc_template.c"  /** * Finalize MDCT and free allocated memory. * * @param s  AC-3 encoder private context */av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s){    ff_mdct_end(&s->mdct);    av_freep(&s->mdct_window);}  /** * Initialize MDCT tables. * * @param s  AC-3 encoder private context * @return   0 on success, negative error code on failure */av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s){    float *window;    int i, n, n2;     n  = 1 << 9;    n2 = n >> 1;     window = av_malloc_array(n, 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, n2);    for (i = 0; i < n2; i++)        window[n-1-i] = window[i];    s->mdct_window = window;     return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);}  /* * Normalize the input samples. * Not needed for the floating-point encoder. */static int normalize_samples(AC3EncodeContext *s){    return 0;}  /* * 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));} 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);} /* * Clip MDCT coefficients to allowable range. */static void clip_coefficients(AudioDSPContext *adsp, float *coef,                              unsigned int len){    adsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);}  /* * 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);} av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx){    AC3EncodeContext *s = avctx->priv_data;    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);    if (!s->fdsp)        return AVERROR(ENOMEM);    return ff_ac3_encode_init(avctx);} AVCodec ff_ac3_encoder = {    .name            = "ac3",    .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),    .type            = AVMEDIA_TYPE_AUDIO,    .id              = AV_CODEC_ID_AC3,    .priv_data_size  = sizeof(AC3EncodeContext),    .init            = ff_ac3_float_encode_init,    .encode2         = ff_ac3_float_encode_frame,    .close           = ff_ac3_encode_close,    .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,                                                      AV_SAMPLE_FMT_NONE },    .priv_class      = &ac3enc_class,    .channel_layouts = ff_ac3_channel_layouts,    .defaults        = ac3_defaults,};