/* * 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 * fixed-point AC-3 encoder. */ #define FFT_FLOAT 0#undef CONFIG_AC3ENC_FLOAT#include "internal.h"#include "audiodsp.h"#include "ac3enc.h"#include "eac3enc.h" #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED#include "ac3enc_opts_template.c" static const AVClass ac3enc_class = {    .class_name = "Fixed-Point AC-3 Encoder",    .item_name  = av_default_item_name,    .option     = ac3_options,    .version    = LIBAVUTIL_VERSION_INT,}; /* * Normalize the input samples to use the maximum available precision. * This assumes signed 16-bit input samples. */static int normalize_samples(AC3EncodeContext *s){    int v = s->ac3dsp.ac3_max_msb_abs_int16(s->windowed_samples, AC3_WINDOW_SIZE);    v = 14 - av_log2(v);    if (v > 0)        s->ac3dsp.ac3_lshift_int16(s->windowed_samples, AC3_WINDOW_SIZE, v);    /* +6 to right-shift from 31-bit to 25-bit */    return v + 6;}  /* * Scale MDCT coefficients to 25-bit signed fixed-point. */static void scale_coefficients(AC3EncodeContext *s){    int blk, ch;     for (blk = 0; blk < s->num_blocks; blk++) {        AC3Block *block = &s->blocks[blk];        for (ch = 1; ch <= s->channels; ch++) {            s->ac3dsp.ac3_rshift_int32(block->mdct_coef[ch], AC3_MAX_COEFS,                                       block->coeff_shift[ch]);        }    }} static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],                                 const int32_t *coef0, const int32_t *coef1,                                 int len){    s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);} /* * Clip MDCT coefficients to allowable range. */static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef,                              unsigned int len){    adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);}  /* * Calculate a single coupling coordinate. */static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl){    if (energy_cpl <= COEF_MAX) {        return 1048576;    } else {        uint64_t coord   = energy_ch / (energy_cpl >> 24);        uint32_t coord32 = FFMIN(coord, 1073741824);        coord32          = ff_sqrt(coord32) << 9;        return FFMIN(coord32, COEF_MAX);    }}  #include "ac3enc_template.c"  /** * Finalize MDCT and free allocated memory. * * @param s  AC-3 encoder private context */av_cold void ff_ac3_fixed_mdct_end(AC3EncodeContext *s){    ff_mdct_end(&s->mdct);}  /** * Initialize MDCT tables. * * @param s  AC-3 encoder private context * @return   0 on success, negative error code on failure */av_cold int ff_ac3_fixed_mdct_init(AC3EncodeContext *s){    int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0);    s->mdct_window = ff_ac3_window;    return ret;}  static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx){    AC3EncodeContext *s = avctx->priv_data;    s->fixed_point = 1;    return ff_ac3_encode_init(avctx);}  AVCodec ff_ac3_fixed_encoder = {    .name            = "ac3_fixed",    .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            = ac3_fixed_encode_init,    .encode2         = ff_ac3_fixed_encode_frame,    .close           = ff_ac3_encode_close,    .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16P,                                                      AV_SAMPLE_FMT_NONE },    .priv_class      = &ac3enc_class,    .channel_layouts = ff_ac3_channel_layouts,    .defaults        = ac3_defaults,};