libavfilter/generate_wave_table.c

   1 /*
   2  * This file is part of FFmpeg.
   3  *
   4  * FFmpeg is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * FFmpeg is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with FFmpeg; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #include <stdint.h>
  20 #include "libavutil/avassert.h"
  21 #include "avfilter.h"
  22 #include "generate_wave_table.h"
  23
  24 void ff_generate_wave_table(enum WaveType wave_type,
  25                             enum AVSampleFormat sample_fmt,
  26                             void *table, int table_size,
  27                             double min, double max, double phase)
  28 {
  29     uint32_t i, phase_offset = phase / M_PI / 2 * table_size + 0.5;
  30
  31     for (i = 0; i < table_size; i++) {
  32         uint32_t point = (i + phase_offset) % table_size;
  33         double d;
  34
  35         switch (wave_type) {
  36         case WAVE_SIN:
  37             d = (sin((double)point / table_size * 2 * M_PI) + 1) / 2;
  38             break;
  39         case WAVE_TRI:
  40             d = (double)point * 2 / table_size;
  41             switch (4 * point / table_size) {
  42             case 0: d = d + 0.5; break;
  43             case 1:
  44             case 2: d = 1.5 - d; break;
  45             case 3: d = d - 1.5; break;
  46             }
  47             break;
  48         default:
  49             av_assert0(0);
  50         }
  51
  52         d  = d * (max - min) + min;
  53         switch (sample_fmt) {
  54         case AV_SAMPLE_FMT_FLT: {
  55             float *fp = (float *)table;
  56             *fp++ = (float)d;
  57             table = fp;
  58             continue; }
  59         case AV_SAMPLE_FMT_DBL: {
  60             double *dp = (double *)table;
  61             *dp++ = d;
  62             table = dp;
  63             continue; }
  64         }
  65
  66         d += d < 0 ? -0.5 : 0.5;
  67         switch (sample_fmt) {
  68         case AV_SAMPLE_FMT_S16: {
  69             int16_t *sp = table;
  70             *sp++ = (int16_t)d;
  71             table = sp;
  72             continue; }
  73         case AV_SAMPLE_FMT_S32: {
  74             int32_t *ip = table;
  75             *ip++ = (int32_t)d;
  76             table = ip;
  77             continue; }
  78         default:
  79             av_assert0(0);
  80         }
  81     }
  82 }