modules/audio_output/volume.h

   1 /*****************************************************************************
   2  * volume.c : helper for software audio amplification
   3  *****************************************************************************
   4  * Copyright (C) 2012 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 #include <stdio.h>
  25 #include <math.h>
  26 #include <vlc_common.h>
  27 #include <vlc_aout.h>
  28
  29 #define add_sw_gain() \
  30         add_float(MODULE_STRING"-gain", 1., N_("Software gain"), \
  31                   N_("This linear gain will be applied in software."), true) \
  32              change_float_range(0., 8.)
  33
  34 static int aout_SoftVolumeSet(audio_output_t *aout, float volume)
  35 {
  36     aout_sys_t *sys = aout->sys;
  37     /*
  38      * Cubic mapping from software volume to amplification factor.
  39      * This provides a good tradeoff between low and high volume ranges.
  40      *
  41      * This code is only used for the VLC software mixer. If you change this
  42      * formula, be sure to update the volume-capable plugins also.
  43      */
  44     float gain = volume * volume * volume;
  45
  46     if (!sys->soft_mute && aout_GainRequest(aout, gain))
  47         return -1;
  48     sys->soft_gain = gain;
  49     if (var_InheritBool(aout, "volume-save"))
  50         config_PutFloat(MODULE_STRING"-gain", gain);
  51
  52     aout_VolumeReport(aout, volume);
  53     return 0;
  54 }
  55
  56 static int aout_SoftMuteSet (audio_output_t *aout, bool mute)
  57 {
  58     aout_sys_t *sys = aout->sys;
  59
  60     if (aout_GainRequest(aout, mute ? 0.f : sys->soft_gain))
  61         return -1;
  62     sys->soft_mute = mute;
  63
  64     aout_MuteReport(aout, mute);
  65     return 0;
  66 }
  67
  68 static void aout_SoftVolumeInit(audio_output_t *aout)
  69 {
  70     aout_sys_t *sys = aout->sys;
  71     float gain = var_InheritFloat(aout, MODULE_STRING"-gain");
  72     bool mute = var_InheritBool(aout, "mute");
  73
  74     aout->volume_set = aout_SoftVolumeSet;
  75     aout->mute_set = aout_SoftMuteSet;
  76     sys->soft_gain = gain;
  77     sys->soft_mute = mute;
  78
  79     aout_MuteReport(aout, mute);
  80     aout_VolumeReport(aout, cbrtf(gain));
  81 }
  82
  83 static void aout_SoftVolumeStart (audio_output_t *aout)
  84 {
  85     aout_sys_t *sys = aout->sys;
  86
  87     if (aout_GainRequest(aout, sys->soft_mute ? 0.f : sys->soft_gain))
  88     {
  89         aout_MuteReport(aout, false);
  90         aout_VolumeReport(aout, 1.f);
  91     }
  92 }