libavcodec/ac3enc_float.c

   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 Libav.
   8  *
   9  * Libav 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  * Libav 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 Libav; 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 "ac3enc.h"
  32 #include "eac3enc.h"
  33 #include "kbdwin.h"
  34
  35
  36 #if CONFIG_AC3_ENCODER
  37 #define AC3ENC_TYPE AC3ENC_TYPE_AC3
  38 #include "ac3enc_opts_template.c"
  39 static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,
  40                                       ac3_options, LIBAVUTIL_VERSION_INT };
  41 #endif
  42
  43 #include "ac3enc_template.c"
  44
  45
  46 /**
  47  * Finalize MDCT and free allocated memory.
  48  *
  49  * @param s  AC-3 encoder private context
  50  */
  51 av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
  52 {
  53     ff_mdct_end(&s->mdct);
  54     av_freep(&s->mdct_window);
  55 }
  56
  57
  58 /**
  59  * Initialize MDCT tables.
  60  *
  61  * @param s  AC-3 encoder private context
  62  * @return   0 on success, negative error code on failure
  63  */
  64 av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
  65 {
  66     float *window;
  67     int i, n, n2;
  68
  69     n  = 1 << 9;
  70     n2 = n >> 1;
  71
  72     window = av_malloc(n * sizeof(*window));
  73     if (!window) {
  74         av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
  75         return AVERROR(ENOMEM);
  76     }
  77     ff_kbd_window_init(window, 5.0, n2);
  78     for (i = 0; i < n2; i++)
  79         window[n-1-i] = window[i];
  80     s->mdct_window = window;
  81
  82     return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
  83 }
  84
  85
  86 /*
  87  * Apply KBD window to input samples prior to MDCT.
  88  */
  89 static void apply_window(void *dsp, float *output,
  90                          const float *input, const float *window,
  91                          unsigned int len)
  92 {
  93     AVFloatDSPContext *fdsp = dsp;
  94     fdsp->vector_fmul(output, input, window, len);
  95 }
  96
  97
  98 /*
  99  * Normalize the input samples.
 100  * Not needed for the floating-point encoder.
 101  */
 102 static int normalize_samples(AC3EncodeContext *s)
 103 {
 104     return 0;
 105 }
 106
 107
 108 /*
 109  * Scale MDCT coefficients from float to 24-bit fixed-point.
 110  */
 111 static void scale_coefficients(AC3EncodeContext *s)
 112 {
 113     int chan_size = AC3_MAX_COEFS * s->num_blocks;
 114     int cpl       = s->cpl_on;
 115     s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
 116                                s->mdct_coef_buffer  + (chan_size * !cpl),
 117                                chan_size * (s->channels + cpl));
 118 }
 119
 120
 121 /*
 122  * Clip MDCT coefficients to allowable range.
 123  */
 124 static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)
 125 {
 126     dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
 127 }
 128
 129
 130 /*
 131  * Calculate a single coupling coordinate.
 132  */
 133 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
 134 {
 135     float coord = 0.125;
 136     if (energy_cpl > 0)
 137         coord *= sqrtf(energy_ch / energy_cpl);
 138     return FFMIN(coord, COEF_MAX);
 139 }
 140
 141
 142 #if CONFIG_AC3_ENCODER
 143 AVCodec ff_ac3_encoder = {
 144     .name            = "ac3",
 145     .type            = AVMEDIA_TYPE_AUDIO,
 146     .id              = AV_CODEC_ID_AC3,
 147     .priv_data_size  = sizeof(AC3EncodeContext),
 148     .init            = ff_ac3_encode_init,
 149     .encode2         = ff_ac3_float_encode_frame,
 150     .close           = ff_ac3_encode_close,
 151     .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
 152                                                       AV_SAMPLE_FMT_NONE },
 153     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
 154     .priv_class      = &ac3enc_class,
 155     .channel_layouts = ff_ac3_channel_layouts,
 156     .defaults        = ac3_defaults,
 157 };
 158 #endif