15 files changed, 219 insertions, 35 deletions

diff --git a/apps/features.txt b/apps/features.txt
index 2262f7502e..bafaa11599 100644
--- a/apps/features.txt
+++ b/apps/features.txt
@@ -296,3 +296,7 @@ hibylinux
     (CONFIG_KEYPAD == IRIVER_H10_PAD)
 clear_settings_on_hold
 #endif
+
+#if defined(HAVE_PERCEPTUAL_VOLUME)
+perceptual_volume
+#endif
diff --git a/apps/gui/list.c b/apps/gui/list.c
index 83d12289f2..652279a9de 100644
--- a/apps/gui/list.c
+++ b/apps/gui/list.c
@@ -663,12 +663,10 @@ bool gui_synclist_do_button(struct gui_synclist * lists, int *actionptr)
 
 #ifdef HAVE_VOLUME_IN_LIST
         case ACTION_LIST_VOLUP:
-            global_settings.volume += sound_steps(SOUND_VOLUME);
-            setvol();
+            adjust_volume(1);
             return true;
         case ACTION_LIST_VOLDOWN:
-            global_settings.volume -= sound_steps(SOUND_VOLUME);
-            setvol();
+            adjust_volume(-1);
             return true;
 #endif
         case ACTION_STD_PREV:
diff --git a/apps/gui/quickscreen.c b/apps/gui/quickscreen.c
index 356f74b283..221dfe3111 100644
--- a/apps/gui/quickscreen.c
+++ b/apps/gui/quickscreen.c
@@ -378,14 +378,12 @@ static int gui_syncquickscreen_run(struct gui_quickscreen * qs, int button_enter
         else if (button == button_enter)
             can_quit = true;
         else if (button == ACTION_QS_VOLUP) {
-            global_settings.volume += sound_steps(SOUND_VOLUME);
-            setvol();
+            adjust_volume(1);
             FOR_NB_SCREENS(i)
                 skin_update(CUSTOM_STATUSBAR, i, SKIN_REFRESH_NON_STATIC);
         }
         else if (button == ACTION_QS_VOLDOWN) {
-            global_settings.volume -= sound_steps(SOUND_VOLUME);
-            setvol();
+            adjust_volume(-1);
             FOR_NB_SCREENS(i)
                 skin_update(CUSTOM_STATUSBAR, i, SKIN_REFRESH_NON_STATIC);
         }
diff --git a/apps/gui/wps.c b/apps/gui/wps.c
index 4b0c7c056f..fe656034b9 100644
--- a/apps/gui/wps.c
+++ b/apps/gui/wps.c
@@ -841,9 +841,9 @@ long gui_wps_show(void)
             case ACTION_WPS_VOLUP: /* fall through */
             case ACTION_WPS_VOLDOWN:
                 if (button == ACTION_WPS_VOLUP)
-                    global_settings.volume += sound_steps(SOUND_VOLUME);
+                    adjust_volume(1);
                 else
-                    global_settings.volume -= sound_steps(SOUND_VOLUME);
+                    adjust_volume(-1);
 
                 setvol();
                 FOR_NB_SCREENS(i)
diff --git a/apps/lang/english.lang b/apps/lang/english.lang
index 3ad2921abe..232541e33f 100644
--- a/apps/lang/english.lang
+++ b/apps/lang/english.lang
@@ -15163,7 +15163,7 @@
 </phrase>
 <phrase>
   id: LANG_DIRECT
-  desc: in the pictureflow settings
+  desc: in the pictureflow settings, also a volume adjustment mode
   user: core
   <source>
     *: "Direct"
@@ -16559,3 +16559,54 @@
     *: "Play Last Shuffled"
   </voice>
 </phrase>
+<phrase>
+  id: LANG_VOLUME_ADJUST_MODE
+  desc: in system settings
+  user: core
+  <source>
+    *: none
+    perceptual_volume: "Volume Adjustment Mode"
+  </source>
+  <dest>
+    *: none
+    perceptual_volume: "Volume Adjustment Mode"
+  </dest>
+  <voice>
+    *: none
+    perceptual_volume: "Volume Adjustment Mode"
+  </voice>
+</phrase>
+<phrase>
+  id: LANG_VOLUME_ADJUST_NORM_STEPS
+  desc: in system settings
+  user: core
+  <source>
+    *: none
+    perceptual_volume: "Number of Volume Steps"
+  </source>
+  <dest>
+    *: none
+    perceptual_volume: "Number of Volume Steps"
+  </dest>
+  <voice>
+    *: none
+    perceptual_volume: "Number of Volume Steps"
+  </voice>
+</phrase>
+<phrase>
+  id: LANG_PERCEPTUAL
+  desc: in system settings -> volume adjustment mode
+  user: core
+  <source>
+    *: none
+    perceptual_volume: "Perceptual"
+  </source>
+  <dest>
+    *: none
+    perceptual_volume: "Perceptual"
+  </dest>
+  <voice>
+    *: none
+    perceptual_volume: "Perceptual"
+  </voice>
+</phrase>
diff --git a/apps/menus/settings_menu.c b/apps/menus/settings_menu.c
index 9d1314c269..bfb69a9942 100644
--- a/apps/menus/settings_menu.c
+++ b/apps/menus/settings_menu.c
@@ -338,6 +338,11 @@ MAKE_MENU(limits_menu, ID2P(LANG_LIMITS_MENU), 0, Icon_NOICON,
            ,&default_glyphs
            );
 
+#ifdef HAVE_PERCEPTUAL_VOLUME
+/* Volume adjustment */
+MENUITEM_SETTING(volume_adjust_mode, &global_settings.volume_adjust_mode, NULL);
+MENUITEM_SETTING(volume_adjust_norm_steps, &global_settings.volume_adjust_norm_steps, NULL);
+#endif
 
 /* Keyclick menu */
 MENUITEM_SETTING(keyclick, &global_settings.keyclick, NULL);
@@ -424,6 +429,10 @@ MAKE_MENU(system_menu, ID2P(LANG_SYSTEM),
             &disk_menu,
 #endif
             &limits_menu,
+#ifdef HAVE_PERCEPTUAL_VOLUME
+            &volume_adjust_mode,
+            &volume_adjust_norm_steps,
+#endif
 #ifdef HAVE_QUICKSCREEN
             &shortcuts_replaces_quickscreen,
 #endif
diff --git a/apps/misc.c b/apps/misc.c
index fd840749cb..e10fceb9af 100644
--- a/apps/misc.c
+++ b/apps/misc.c
@@ -824,6 +824,113 @@ void setvol(void)
     settings_save();
 }
 
+#ifdef HAVE_PERCEPTUAL_VOLUME
+static short norm_tab[MAX_NORM_VOLUME_STEPS+2];
+static int norm_tab_num_steps;
+static int norm_tab_size;
+
+static void update_norm_tab(void)
+{
+    const int lim = global_settings.volume_adjust_norm_steps;
+    if (lim == norm_tab_num_steps)
+        return;
+    norm_tab_num_steps = lim;
+
+    const int min = sound_min(SOUND_VOLUME);
+    const int max = sound_max(SOUND_VOLUME);
+    const int step = sound_steps(SOUND_VOLUME);
+
+    /* Ensure the table contains the minimum volume */
+    norm_tab[0] = min;
+    norm_tab_size = 1;
+
+    for (int i = 0; i < lim; ++i)
+    {
+        int vol = from_normalized_volume(i, min, max, lim);
+        int rem = vol % step;
+
+        vol -= rem;
+        if (abs(rem) > step/2)
+            vol += rem < 0 ? -step : step;
+
+        /* Add volume step, ignoring any duplicate entries that may
+         * occur due to rounding */
+        if (vol != norm_tab[norm_tab_size-1])
+            norm_tab[norm_tab_size++] = vol;
+    }
+
+    /* Ensure the table contains the maximum volume */
+    if (norm_tab[norm_tab_size-1] != max)
+        norm_tab[norm_tab_size++] = max;
+}
+
+void set_normalized_volume(int vol)
+{
+    update_norm_tab();
+
+    if (vol < 0)
+        vol = 0;
+    if (vol >= norm_tab_size)
+        vol = norm_tab_size - 1;
+
+    global_settings.volume = norm_tab[vol];
+}
+
+int get_normalized_volume(void)
+{
+    update_norm_tab();
+
+    int a = 0, b = norm_tab_size - 1;
+    while (a != b)
+    {
+        int i = (a + b + 1) / 2;
+        if (global_settings.volume < norm_tab[i])
+            b = i - 1;
+        else
+            a = i;
+    }
+
+    return a;
+}
+#else
+void set_normalized_volume(int vol)
+{
+    global_settings.volume = vol * sound_steps(SOUND_VOLUME);
+}
+
+int get_normalized_volume(void)
+{
+    return global_settings.volume / sound_steps(SOUND_VOLUME);
+}
+#endif
+
+void adjust_volume(int steps)
+{
+#ifdef HAVE_PERCEPTUAL_VOLUME
+    adjust_volume_ex(steps, global_settings.volume_adjust_mode);
+#else
+    adjust_volume_ex(steps, VOLUME_ADJUST_DIRECT);
+#endif
+}
+
+void adjust_volume_ex(int steps, enum volume_adjust_mode mode)
+{
+    switch (mode)
+    {
+    case VOLUME_ADJUST_PERCEPTUAL:
+#ifdef HAVE_PERCEPTUAL_VOLUME
+        set_normalized_volume(get_normalized_volume() + steps);
+        break;
+#endif
+    case VOLUME_ADJUST_DIRECT:
+    default:
+        global_settings.volume += steps * sound_steps(SOUND_VOLUME);
+        break;
+    }
+
+    setvol();
+}
+
 char* strrsplt(char* str, int c)
 {
     char* s = strrchr(str, c);
diff --git a/apps/misc.h b/apps/misc.h
index 72b8735c8a..b7a9a5c42c 100644
--- a/apps/misc.h
+++ b/apps/misc.h
@@ -137,8 +137,22 @@ void check_bootfile(bool do_rolo);
 #endif
 #endif
 
+enum volume_adjust_mode
+{
+    VOLUME_ADJUST_DIRECT,       /* adjust in units of the volume step size */
+    VOLUME_ADJUST_PERCEPTUAL,   /* adjust using perceptual steps */
+};
+
+/* min/max values for global_settings.volume_adjust_norm_steps */
+#define MIN_NORM_VOLUME_STEPS 10
+#define MAX_NORM_VOLUME_STEPS 100
+
 /* check range, set volume and save settings */
 void setvol(void);
+void set_normalized_volume(int vol);
+int get_normalized_volume(void);
+void adjust_volume(int steps);
+void adjust_volume_ex(int steps, enum volume_adjust_mode mode);
 
 #ifdef HAVE_LCD_COLOR
 int hex_to_rgb(const char* hex, int* color);
diff --git a/apps/plugin.c b/apps/plugin.c
index 00fac21b8d..cdbe340ddd 100644
--- a/apps/plugin.c
+++ b/apps/plugin.c
@@ -828,6 +828,7 @@ static const struct plugin_api rockbox_api = {
 #if defined(HAVE_TAGCACHE)
     tagtree_subentries_do_action,
 #endif
+    adjust_volume,
 };
 
 static int plugin_buffer_handle;
diff --git a/apps/plugin.h b/apps/plugin.h
index 20df7e72f2..286a5e2794 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -158,7 +158,7 @@ int plugin_open(const char *plugin, const char *parameter);
 #define PLUGIN_MAGIC 0x526F634B /* RocK */
 
 /* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 264
+#define PLUGIN_API_VERSION 265
 
 /* update this to latest version if a change to the api struct breaks
    backwards compatibility (and please take the opportunity to sort in any
@@ -954,6 +954,7 @@ struct plugin_api {
 #ifdef HAVE_TAGCACHE
     bool (*tagtree_subentries_do_action)(bool (*action_cb)(const char *file_name));
 #endif
+    void (*adjust_volume)(int steps);
 };
 
 /* plugin header */
diff --git a/apps/plugins/lrcplayer.c b/apps/plugins/lrcplayer.c
index 71e5310638..de31733671 100644
--- a/apps/plugins/lrcplayer.c
+++ b/apps/plugins/lrcplayer.c
@@ -2625,16 +2625,10 @@ static int handle_button(void)
                 ff_rewind(0, false);
             break;
         case ACTION_WPS_VOLDOWN:
-            limit = rb->sound_min(SOUND_VOLUME);
-            if (--rb->global_settings->volume < limit)
-                rb->global_settings->volume = limit;
-            rb->sound_set(SOUND_VOLUME, rb->global_settings->volume);
+            rb->adjust_volume(-1);
             break;
         case ACTION_WPS_VOLUP:
-            limit = rb->sound_max(SOUND_VOLUME);
-            if (++rb->global_settings->volume > limit)
-                rb->global_settings->volume = limit;
-            rb->sound_set(SOUND_VOLUME, rb->global_settings->volume);
+            rb->adjust_volume(1);
             break;
         case ACTION_WPS_CONTEXT:
             ret = LRC_GOTO_EDITOR;
diff --git a/apps/plugins/mikmod/mikmod.c b/apps/plugins/mikmod/mikmod.c
index 6622b5fdb6..65633c0ad1 100644
--- a/apps/plugins/mikmod/mikmod.c
+++ b/apps/plugins/mikmod/mikmod.c
@@ -710,7 +710,6 @@ static void mm_errorhandler(void)
 
 static int playfile(char* filename)
 {
-    int vol = 0;
     int button;
     int retval = PLUGIN_OK;
     bool changingpos = false;
@@ -789,13 +788,8 @@ static int playfile(char* filename)
                 }
                 break;
             }
-            vol = rb->global_settings->volume;
-            if (vol < rb->sound_max(SOUND_VOLUME))
-            {
-                vol++;
-                rb->sound_set(SOUND_VOLUME, vol);
-                rb->global_settings->volume = vol;
-            }
+
+            rb->adjust_volume(1);
             break;
 
         case ACTION_WPS_VOLDOWN:
@@ -808,13 +802,8 @@ static int playfile(char* filename)
                 }
                 break;
             }
-            vol = rb->global_settings->volume;
-            if (vol > rb->sound_min(SOUND_VOLUME))
-            {
-                vol--;
-                rb->sound_set(SOUND_VOLUME, vol);
-                rb->global_settings->volume = vol;
-            }
+
+            rb->adjust_volume(-1);
             break;
 
         case ACTION_WPS_SKIPPREV:
diff --git a/apps/plugins/sdl/SDL_mixer/timidity/playmidi.c b/apps/plugins/sdl/SDL_mixer/timidity/playmidi.c
index 1638732dc5..38f7109b13 100644
--- a/apps/plugins/sdl/SDL_mixer/timidity/playmidi.c
+++ b/apps/plugins/sdl/SDL_mixer/timidity/playmidi.c
@@ -21,6 +21,8 @@
 
 #include "tables.h"
 
+/* ROCKBOX HACK: avoid a conflict with adjust_volume() in misc.h */
+#define adjust_volume adjust_midi_volume
 
 static int opt_expression_curve = 2;
 static int opt_volume_curve = 2;
diff --git a/apps/settings.h b/apps/settings.h
index 1ad1923c73..ca10c45d5f 100644
--- a/apps/settings.h
+++ b/apps/settings.h
@@ -855,6 +855,11 @@ struct user_settings
 #endif
     int volume_limit; /* maximum volume limit */
 
+#ifdef HAVE_PERCEPTUAL_VOLUME
+    int volume_adjust_mode;
+    int volume_adjust_norm_steps;
+#endif
+
     int surround_enabled;
     int surround_balance;
     int surround_fx1;
diff --git a/apps/settings_list.c b/apps/settings_list.c
index 60ac4192fa..315f39b21f 100644
--- a/apps/settings_list.c
+++ b/apps/settings_list.c
@@ -40,6 +40,7 @@
 #include "powermgmt.h"
 #include "kernel.h"
 #include "open_plugin.h"
+#include "misc.h"
 #ifdef HAVE_REMOTE_LCD
 #include "lcd-remote.h"
 #endif
@@ -1057,6 +1058,16 @@ const struct settings_list settings[] = {
                 MAX_FILES_IN_DIR_STEP /* min */, MAX_FILES_IN_DIR_MAX,
                 MAX_FILES_IN_DIR_STEP,
                 NULL, NULL, NULL),
+#ifdef HAVE_PERCEPTUAL_VOLUME
+    CHOICE_SETTING(0, volume_adjust_mode, LANG_VOLUME_ADJUST_MODE,
+                   VOLUME_ADJUST_DIRECT, "volume adjustment mode",
+                   "direct,perceptual", NULL, 2,
+                   ID2P(LANG_DIRECT), ID2P(LANG_PERCEPTUAL)),
+    INT_SETTING_NOWRAP(0, volume_adjust_norm_steps, LANG_VOLUME_ADJUST_NORM_STEPS,
+                       50, "perceptual volume step count", UNIT_INT,
+                       MIN_NORM_VOLUME_STEPS, MAX_NORM_VOLUME_STEPS, 5,
+                       NULL, NULL, NULL),
+#endif
 /* use this setting for user code even if there's no exchangable battery
  * support enabled */
 #if BATTERY_CAPACITY_INC > 0