feat(volume): Added volume mapping

include/adapters/alsa.hpp

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <functional>
 #include <string>
+#include <cmath>
 
 #include <alsa/asoundlib.h>
 
@@ -10,6 +11,8 @@
 #include "config.hpp"
 #include "utils/threading.hpp"
 
+#define MAX_LINEAR_DB_SCALE 24
+
 LEMONBUDDY_NS
 
 DEFINE_ERROR(alsa_exception);
@@ -64,7 +67,9 @@ class alsa_mixer {
   int process_events();
 
   int get_volume();
+  int get_normalized_volume();
   void set_volume(float percentage);
+  void set_normalized_volume(float percentage);
   void set_mute(bool mode);
   void toggle_mute();
   bool is_muted();

include/modules/volume.hpp

@@ -57,6 +57,8 @@ namespace modules {
 
     int m_headphoneid = 0;
 
+    bool m_mapped;
+
     stateflag m_muted{false};
     stateflag m_headphones{false};
 

src/adapters/alsa.cpp

@@ -169,6 +169,35 @@ int alsa_mixer::get_volume() {
   return 100.0f * (vol_total / chan_n) / vol_max + 0.5f;
 }
 
+int alsa_mixer::get_normalized_volume() {
+  std::lock_guard<threading_util::spin_lock> guard(m_lock);
+  long chan_n = 0, vol_total = 0, vol, vol_min, vol_max;
+  double normalized, min_norm;
+
+  snd_mixer_selem_get_playback_dB_range(m_mixerelement, &vol_min, &vol_max);
+
+  for (int i = 0; i <= SND_MIXER_SCHN_LAST; i++) {
+    if (snd_mixer_selem_has_playback_channel(
+            m_mixerelement, static_cast<snd_mixer_selem_channel_id_t>(i))) {
+      snd_mixer_selem_get_playback_dB(
+          m_mixerelement, static_cast<snd_mixer_selem_channel_id_t>(i), &vol);
+      vol_total += vol;
+      chan_n++;
+    }
+  }
+
+  if (vol_max - vol_min <= MAX_LINEAR_DB_SCALE * 100)
+    return 100.0f * (vol_total / chan_n - vol_min) / (vol_max - vol_min) + 0.5f;
+
+  normalized = pow10((vol_total / chan_n - vol_max) / 6000.0);
+  if (vol_min != SND_CTL_TLV_DB_GAIN_MUTE) {
+    min_norm = pow10((vol_min - vol_max) / 6000.0);
+    normalized = (normalized - min_norm) / (1 - min_norm);
+  }
+
+  return 100.0f * normalized + 0.5f;
+}
+
 void alsa_mixer::set_volume(float percentage) {
   if (is_muted())
     return;
@@ -181,6 +210,31 @@ void alsa_mixer::set_volume(float percentage) {
   snd_mixer_selem_set_playback_volume_all(m_mixerelement, vol_max * percentage / 100);
 }
 
+void alsa_mixer::set_normalized_volume(float percentage) {
+  if (is_muted())
+    return;
+
+  std::lock_guard<threading_util::spin_lock> guard(m_lock);
+
+  long vol_min, vol_max;
+  double min_norm;
+  percentage = percentage / 100.0f;
+
+  snd_mixer_selem_get_playback_dB_range(m_mixerelement, &vol_min, &vol_max);
+
+  if (vol_max - vol_min <= MAX_LINEAR_DB_SCALE * 100) {
+    snd_mixer_selem_set_playback_dB_all(m_mixerelement, lrint(percentage * (vol_max - vol_min)) + vol_min, 0);
+    return;
+  }
+
+  if (vol_min != SND_CTL_TLV_DB_GAIN_MUTE) {
+    min_norm = pow10((vol_min - vol_max) / 6000.0);
+    percentage = percentage * (1 - min_norm) + min_norm;
+  }
+
+  snd_mixer_selem_set_playback_dB_all(m_mixerelement, lrint(6000.0 * log10(percentage)) + vol_max, 0);
+}
+
 void alsa_mixer::set_mute(bool mode) {
   std::lock_guard<threading_util::spin_lock> guard(m_lock);
   snd_mixer_selem_set_playback_switch_all(m_mixerelement, mode);

src/modules/volume.cpp

@@ -14,6 +14,7 @@ namespace modules {
     GET_CONFIG_VALUE(name(), master_mixer_name, "master-mixer");
     GET_CONFIG_VALUE(name(), speaker_mixer_name, "speaker-mixer");
     GET_CONFIG_VALUE(name(), headphone_mixer_name, "headphone-mixer");
+    m_mapped = m_conf.get<bool>(name(), "mapped", false);
 
     if (!headphone_mixer_name.empty())
       REQ_CONFIG_VALUE(name(), m_headphoneid, "headphone-id");
@@ -110,16 +111,19 @@ namespace modules {
     m_headphones = false;
 
     if (m_mixers[mixer::MASTER]) {
-      m_volume = m_volume * m_mixers[mixer::MASTER]->get_volume() / 100.0f;
+      m_volume = m_volume * (m_mapped ? m_mixers[mixer::MASTER]->get_normalized_volume() / 100.0f :
+        m_mixers[mixer::MASTER]->get_volume() / 100.0f);
       m_muted = m_muted || m_mixers[mixer::MASTER]->is_muted();
     }
 
     if (m_controls[control::HEADPHONE] && m_controls[control::HEADPHONE]->test_device_plugged()) {
       m_headphones = true;
-      m_volume = m_volume * m_mixers[mixer::HEADPHONE]->get_volume() / 100.0f;
+      m_volume = m_volume * (m_mapped ? m_mixers[mixer::HEADPHONE]->get_normalized_volume() / 100.0f :
+        m_mixers[mixer::HEADPHONE]->get_volume() / 100.0f);
       m_muted = m_muted || m_mixers[mixer::HEADPHONE]->is_muted();
     } else if (m_mixers[mixer::SPEAKER]) {
-      m_volume = m_volume * m_mixers[mixer::SPEAKER]->get_volume() / 100.0f;
+      m_volume = m_volume * (m_mapped ? m_mixers[mixer::SPEAKER]->get_normalized_volume() / 100.0f :
+        m_mixers[mixer::SPEAKER]->get_volume() / 100.0f);
       m_muted = m_muted || m_mixers[mixer::SPEAKER]->is_muted();
     }
 
@@ -196,11 +200,15 @@ namespace modules {
         }
       } else if (cmd.compare(0, strlen(EVENT_VOLUME_UP), EVENT_VOLUME_UP) == 0) {
         for (auto&& mixer : mixers) {
-          mixer->set_volume(math_util::cap<float>(mixer->get_volume() + 5, 0, 100));
+          m_mapped ?
+            mixer->set_normalized_volume(math_util::cap<float>(mixer->get_normalized_volume() + 5, 0, 100)) :
+            mixer->set_volume(math_util::cap<float>(mixer->get_volume() + 5, 0, 100));
         }
       } else if (cmd.compare(0, strlen(EVENT_VOLUME_DOWN), EVENT_VOLUME_DOWN) == 0) {
         for (auto&& mixer : mixers) {
-          mixer->set_volume(math_util::cap<float>(mixer->get_volume() - 5, 0, 100));
+          m_mapped ?
+            mixer->set_normalized_volume(math_util::cap<float>(mixer->get_normalized_volume() - 5, 0, 100)) :
+            mixer->set_volume(math_util::cap<float>(mixer->get_volume() - 5, 0, 100));
         }
       } else {
         return false;