/* * 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 Libav. * * Libav 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. * * Libav 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 Libav; 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 "ac3enc.h"#include "eac3enc.h"#include "kbdwin.h"  #if CONFIG_AC3_ENCODER#define AC3ENC_TYPE AC3ENC_TYPE_AC3#include "ac3enc_opts_template.c"static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,                                      ac3_options, LIBAVUTIL_VERSION_INT };#endif #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(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);}  /* * Apply KBD window to input samples prior to MDCT. */static void apply_window(void *dsp, float *output,                         const float *input, const float *window,                         unsigned int len){    AVFloatDSPContext *fdsp = dsp;    fdsp->vector_fmul(output, input, window, len);}  /* * 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));}  /* * Clip MDCT coefficients to allowable range. */static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len){    dsp->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);}  #if CONFIG_AC3_ENCODERAVCodec ff_ac3_encoder = {    .name            = "ac3",    .type            = AVMEDIA_TYPE_AUDIO,    .id              = CODEC_ID_AC3,    .priv_data_size  = sizeof(AC3EncodeContext),    .init            = ff_ac3_encode_init,    .encode2         = ff_ac3_float_encode_frame,    .close           = ff_ac3_encode_close,    .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLT,                                                      AV_SAMPLE_FMT_NONE },    .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),    .priv_class      = &ac3enc_class,    .channel_layouts = ff_ac3_channel_layouts,    .defaults        = ac3_defaults,};#endif