--- /dev/null
+/*****************************************************************************
+ * volume.c : helper for software audio amplification
+ *****************************************************************************
+ * Copyright (C) 2012 Rémi Denis-Courmont
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <stdio.h>
+#include <math.h>
+#include <vlc_common.h>
+#include <vlc_aout.h>
+
+#define add_sw_gain() \
+ add_float(MODULE_STRING"-gain", 1., N_("Software gain"), \
+ N_("This linear gain will be applied in software."), true) \
+ change_float_range(0., 8.)
+
+static int aout_SoftVolumeSet(audio_output_t *aout, float volume)
+{
+ aout_sys_t *sys = aout->sys;
+ /*
+ * Cubic mapping from software volume to amplification factor.
+ * This provides a good tradeoff between low and high volume ranges.
+ *
+ * This code is only used for the VLC software mixer. If you change this
+ * formula, be sure to update the volume-capable plugins also.
+ */
+ float gain = volume * volume * volume;
+
+ if (!sys->soft_mute && aout_GainRequest(aout, gain))
+ return -1;
+ sys->soft_gain = gain;
+ if (var_InheritBool(aout, "volume-save"))
+ config_PutFloat(aout, MODULE_STRING"-gain", gain);
+
+ aout_VolumeReport(aout, volume);
+ return 0;
+}
+
+static int aout_SoftMuteSet (audio_output_t *aout, bool mute)
+{
+ aout_sys_t *sys = aout->sys;
+
+ if (aout_GainRequest(aout, mute ? 0.f : sys->soft_gain))
+ return -1;
+ sys->soft_mute = mute;
+
+ aout_MuteReport(aout, mute);
+ return 0;
+}
+
+static void aout_SoftVolumeInit(audio_output_t *aout)
+{
+ aout_sys_t *sys = aout->sys;
+ float gain = var_InheritFloat(aout, MODULE_STRING"-gain");
+ bool mute = var_InheritBool(aout, "mute");
+
+ if (aout_GainRequest(aout, mute ? 0.f : gain))
+ {
+ mute = false;
+ gain = 1.f;
+ }
+
+ aout->volume_set = aout_SoftVolumeSet;
+ aout->mute_set = aout_SoftMuteSet;
+ sys->soft_gain = gain;
+ sys->soft_mute = mute;
+
+ aout_MuteReport(aout, mute);
+ aout_VolumeReport(aout, cbrtf(gain));
+}