/*
  * 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 & 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,

 };