Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * The simplest AC-3 encoder
  3.  * Copyright (c) 2000 Fabrice Bellard
  4.  * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
  5.  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
  6.  *
  7.  * This file is part of FFmpeg.
  8.  *
  9.  * FFmpeg is free software; you can redistribute it and/or
  10.  * modify it under the terms of the GNU Lesser General Public
  11.  * License as published by the Free Software Foundation; either
  12.  * version 2.1 of the License, or (at your option) any later version.
  13.  *
  14.  * FFmpeg is distributed in the hope that it will be useful,
  15.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17.  * Lesser General Public License for more details.
  18.  *
  19.  * You should have received a copy of the GNU Lesser General Public
  20.  * License along with FFmpeg; if not, write to the Free Software
  21.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22.  */
  23.  
  24. /**
  25.  * @file
  26.  * floating-point AC-3 encoder.
  27.  */
  28.  
  29. #define CONFIG_AC3ENC_FLOAT 1
  30. #include "internal.h"
  31. #include "audiodsp.h"
  32. #include "ac3enc.h"
  33. #include "eac3enc.h"
  34. #include "kbdwin.h"
  35.  
  36.  
  37. #define AC3ENC_TYPE AC3ENC_TYPE_AC3
  38. #include "ac3enc_opts_template.c"
  39. static const AVClass ac3enc_class = {
  40.     .class_name = "AC-3 Encoder",
  41.     .item_name  = av_default_item_name,
  42.     .option     = ac3_options,
  43.     .version    = LIBAVUTIL_VERSION_INT,
  44. };
  45.  
  46. #include "ac3enc_template.c"
  47.  
  48.  
  49. /**
  50.  * Finalize MDCT and free allocated memory.
  51.  *
  52.  * @param s  AC-3 encoder private context
  53.  */
  54. av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
  55. {
  56.     ff_mdct_end(&s->mdct);
  57.     av_freep(&s->mdct_window);
  58. }
  59.  
  60.  
  61. /**
  62.  * Initialize MDCT tables.
  63.  *
  64.  * @param s  AC-3 encoder private context
  65.  * @return   0 on success, negative error code on failure
  66.  */
  67. av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
  68. {
  69.     float *window;
  70.     int i, n, n2;
  71.  
  72.     n  = 1 << 9;
  73.     n2 = n >> 1;
  74.  
  75.     window = av_malloc_array(n, sizeof(*window));
  76.     if (!window) {
  77.         av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
  78.         return AVERROR(ENOMEM);
  79.     }
  80.     ff_kbd_window_init(window, 5.0, n2);
  81.     for (i = 0; i < n2; i++)
  82.         window[n-1-i] = window[i];
  83.     s->mdct_window = window;
  84.  
  85.     return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
  86. }
  87.  
  88.  
  89. /*
  90.  * Normalize the input samples.
  91.  * Not needed for the floating-point encoder.
  92.  */
  93. static int normalize_samples(AC3EncodeContext *s)
  94. {
  95.     return 0;
  96. }
  97.  
  98.  
  99. /*
  100.  * Scale MDCT coefficients from float to 24-bit fixed-point.
  101.  */
  102. static void scale_coefficients(AC3EncodeContext *s)
  103. {
  104.     int chan_size = AC3_MAX_COEFS * s->num_blocks;
  105.     int cpl       = s->cpl_on;
  106.     s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
  107.                                s->mdct_coef_buffer  + (chan_size * !cpl),
  108.                                chan_size * (s->channels + cpl));
  109. }
  110.  
  111. static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],
  112.                                  const float *coef0, const float *coef1,
  113.                                  int len)
  114. {
  115.     s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);
  116. }
  117.  
  118. /*
  119.  * Clip MDCT coefficients to allowable range.
  120.  */
  121. static void clip_coefficients(AudioDSPContext *adsp, float *coef,
  122.                               unsigned int len)
  123. {
  124.     adsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
  125. }
  126.  
  127.  
  128. /*
  129.  * Calculate a single coupling coordinate.
  130.  */
  131. static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
  132. {
  133.     float coord = 0.125;
  134.     if (energy_cpl > 0)
  135.         coord *= sqrtf(energy_ch / energy_cpl);
  136.     return FFMIN(coord, COEF_MAX);
  137. }
  138.  
  139. av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)
  140. {
  141.     AC3EncodeContext *s = avctx->priv_data;
  142.     s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
  143.     if (!s->fdsp)
  144.         return AVERROR(ENOMEM);
  145.     return ff_ac3_encode_init(avctx);
  146. }
  147.  
  148. AVCodec ff_ac3_encoder = {
  149.     .name            = "ac3",
  150.     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
  151.     .type            = AVMEDIA_TYPE_AUDIO,
  152.     .id              = AV_CODEC_ID_AC3,
  153.     .priv_data_size  = sizeof(AC3EncodeContext),
  154.     .init            = ff_ac3_float_encode_init,
  155.     .encode2         = ff_ac3_float_encode_frame,
  156.     .close           = ff_ac3_encode_close,
  157.     .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
  158.                                                       AV_SAMPLE_FMT_NONE },
  159.     .priv_class      = &ac3enc_class,
  160.     .channel_layouts = ff_ac3_channel_layouts,
  161.     .defaults        = ac3_defaults,
  162. };
  163.