modules/audio_mixer/fixed32.c

   1 /*****************************************************************************
   2  * fixed32.c : fixed-point software volume
   3  *****************************************************************************
   4  * Copyright (C) 2011 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <vlc_common.h>
  26 #include <vlc_plugin.h>
  27 #include <vlc_aout.h>
  28 #include <vlc_aout_mixer.h>
  29
  30 static int Activate (vlc_object_t *);
  31
  32 vlc_module_begin ()
  33     set_category (CAT_AUDIO)
  34     set_subcategory (SUBCAT_AUDIO_MISC)
  35     set_description (N_("Fixed-point audio mixer"))
  36     set_capability ("audio mixer", 9)
  37     set_callbacks (Activate, NULL)
  38 vlc_module_end ()
  39
  40 static void FilterFI32 (audio_mixer_t *, block_t *, float);
  41 static void FilterS16N (audio_mixer_t *, block_t *, float);
  42
  43 static int Activate (vlc_object_t *obj)
  44 {
  45     audio_mixer_t *mixer = (audio_mixer_t *)obj;
  46
  47     switch (mixer->format)
  48     {
  49         case VLC_CODEC_FI32:
  50             mixer->mix = FilterFI32;
  51             break;
  52         case VLC_CODEC_S16N:
  53             mixer->mix = FilterS16N;
  54             break;
  55         default:
  56             return -1;
  57     }
  58     return 0;
  59 }
  60
  61 static void FilterFI32 (audio_mixer_t *mixer, block_t *block, float volume)
  62 {
  63     const int64_t mult = volume * 0x1.p32;
  64
  65     if (mult == 0x1.p32)
  66         return;
  67
  68     int32_t *p = (int32_t *)block->p_buffer;
  69
  70     for (size_t n = block->i_buffer / sizeof (*p); n > 0; n--)
  71     {
  72         *p = (*p * mult) >> INT64_C(32);
  73         p++;
  74     }
  75
  76     (void) mixer;
  77 }
  78
  79 static void FilterS16N (audio_mixer_t *mixer, block_t *block, float volume)
  80 {
  81     int32_t mult = volume * 0x1.p16;
  82
  83     if (mult == 0x10000)
  84         return;
  85
  86     int16_t *p = (int16_t *)block->p_buffer;
  87
  88     if (mult < 0x10000)
  89     {
  90         for (size_t n = block->i_buffer / sizeof (*p); n > 0; n--)
  91         {
  92             *p = (*p * mult) >> 16;
  93             p++;
  94         }
  95     }
  96     else
  97     {
  98         mult >>= 4;
  99         for (size_t n = block->i_buffer / sizeof (*p); n > 0; n--)
 100         {
 101             int32_t v = (*p * mult) >> 12;
 102             if (abs (v) > 0x7fff)
 103                 v = 0x8000;
 104             *(p++) = v;
 105         }
 106     }
 107
 108     (void) mixer;
 109 }