Add volume control.

It imposes no performance loss as it is performed
during s16->float conversion.

It is however grouped together with check_mute.

audio/utils.c

@@ -22,10 +22,11 @@
 #endif
 
 void audio_convert_s16_to_float_C(float *out,
-      const int16_t *in, size_t samples)
+      const int16_t *in, size_t samples, float gain)
 {
+   gain = gain / 0x8000;
    for (size_t i = 0; i < samples; i++)
-      out[i] = (float)in[i] / 0x8000; 
+      out[i] = (float)in[i] * gain; 
 }
 
 void audio_convert_float_to_s16_C(int16_t *out,
@@ -40,9 +41,10 @@ void audio_convert_float_to_s16_C(int16_t *out,
 
 #if __SSE2__
 void audio_convert_s16_to_float_SSE2(float *out,
-      const int16_t *in, size_t samples)
+      const int16_t *in, size_t samples, float gain)
 {
-   __m128 factor = _mm_set1_ps(1.0f / (0x7fff * 0x10000));
+   float fgain = gain / (0x7fff * 0x10000);
+   __m128 factor = _mm_set1_ps(fgain);
    size_t i;
    for (i = 0; i + 8 <= samples; i += 8, in += 8, out += 8)
    {
@@ -61,7 +63,7 @@ void audio_convert_s16_to_float_SSE2(float *out,
       _mm_storeu_ps(out + 4, output[1]);
    }
 
-   audio_convert_s16_to_float_C(out, in, samples - i);
+   audio_convert_s16_to_float_C(out, in, samples - i, gain);
 }
 
 void audio_convert_float_to_s16_SSE2(int16_t *out,
@@ -84,8 +86,9 @@ void audio_convert_float_to_s16_SSE2(int16_t *out,
 }
 #elif __ALTIVEC__
 void audio_convert_s16_to_float_altivec(float *out,
-      const int16_t *in, size_t samples)
+      const int16_t *in, size_t samples, float gain)
 {
+   const vector float gain_vec = vec_splats(gain);
    // Unaligned loads/store is a bit expensive, so we optimize for the good path (very likely).
    if (((uintptr_t)out & 15) + ((uintptr_t)in & 15) == 0)
    {
@@ -95,17 +98,17 @@ void audio_convert_s16_to_float_altivec(float *out,
          vector signed short input = vec_ld(0, in);
          vector signed int hi = vec_unpackh(input);
          vector signed int lo = vec_unpackl(input);
-         vector float out_hi = vec_ctf(hi, 15);
-         vector float out_lo = vec_ctf(lo, 15);
+         vector float out_hi = vec_mul(vec_ctf(hi, 15), gain_vec);
+         vector float out_lo = vec_mul(vec_ctf(lo, 15), gain_vec);
 
          vec_st(out_hi,  0, out);
          vec_st(out_lo, 16, out);
       }
 
-      audio_convert_s16_to_float_C(out, in, samples - i);
+      audio_convert_s16_to_float_C(out, in, samples - i, gain);
    }
    else
-      audio_convert_s16_to_float_C(out, in, samples);
+      audio_convert_s16_to_float_C(out, in, samples, gain);
 }
 
 void audio_convert_float_to_s16_altivec(int16_t *out,

audio/utils.h

@@ -24,7 +24,7 @@
 #define audio_convert_float_to_s16 audio_convert_float_to_s16_SSE2
 
 void audio_convert_s16_to_float_SSE2(float *out,
-      const int16_t *in, size_t samples);
+      const int16_t *in, size_t samples, float gain);
 
 void audio_convert_float_to_s16_SSE2(int16_t *out,
       const float *in, size_t samples);
@@ -34,7 +34,7 @@ void audio_convert_float_to_s16_SSE2(int16_t *out,
 #define audio_convert_float_to_s16 audio_convert_float_to_s16_altivec
 
 void audio_convert_s16_to_float_altivec(float *out,
-      const int16_t *in, size_t samples);
+      const int16_t *in, size_t samples, float gain);
 
 void audio_convert_float_to_s16_altivec(int16_t *out,
       const float *in, size_t samples);
@@ -45,7 +45,7 @@ void audio_convert_float_to_s16_altivec(int16_t *out,
 #endif
 
 void audio_convert_s16_to_float_C(float *out,
-      const int16_t *in, size_t samples);
+      const int16_t *in, size_t samples, float gain);
 void audio_convert_float_to_s16_C(int16_t *out,
       const float *in, size_t samples);
 

config.def.h

@@ -280,6 +280,9 @@ static const float rate_control_delta = 0.006;
 static const float rate_control_delta = 0.005;
 #endif
 
+// Default audio volume in dB. (0.0 dB == unity gain).
+static const float audio_volume = 0.0;
+
 //////////////
 // Misc
 //////////////
@@ -391,6 +394,8 @@ static const struct retro_keybind retro_keybinds_1[] = {
    { true, RARCH_NETPLAY_FLIP,               RETROK_i,      NO_BTN,      AXIS_NONE },
    { true, RARCH_SLOWMOTION,                 RETROK_e,      NO_BTN,      AXIS_NONE },
    { true, RARCH_ENABLE_HOTKEY,              RETROK_UNKNOWN, NO_BTN,     AXIS_NONE },
+   { true, RARCH_VOLUME_UP,                  RETROK_KP_PLUS, NO_BTN,     AXIS_NONE },
+   { true, RARCH_VOLUME_DOWN,                RETROK_KP_MINUS, NO_BTN,    AXIS_NONE },
 };
 
 // Player 2-5

driver.c

@@ -388,6 +388,9 @@ void init_audio(void)
          RARCH_WARN("Audio rate control was desired, but driver does not support needed features.\n");
    }
 
+   g_extern.audio_data.volume_db   = g_settings.audio.volume;
+   g_extern.audio_data.volume_gain = db_to_gain(g_settings.audio.volume);
+
 #ifdef HAVE_DYLIB
    init_dsp_plugin();
 #endif

driver.h

@@ -86,6 +86,8 @@ enum // RetroArch specific bind IDs.
    RARCH_NETPLAY_FLIP,
    RARCH_SLOWMOTION,
    RARCH_ENABLE_HOTKEY,
+   RARCH_VOLUME_UP,
+   RARCH_VOLUME_DOWN,
 
 #ifdef RARCH_CONSOLE
    RARCH_CHEAT_INPUT,

general.h

@@ -159,6 +159,7 @@ struct settings
 
       bool rate_control;
       float rate_control_delta;
+      float volume; // dB scale
    } audio;
 
    struct
@@ -341,6 +342,9 @@ struct global
       bool rate_control; 
       double orig_src_ratio;
       size_t driver_buffer_size;
+
+      float volume_db;
+      float volume_gain;
    } audio_data;
 
    struct
@@ -679,6 +683,11 @@ static inline uint16_t swap_if_little16(uint16_t val)
       return val;
 }
 
+static inline float db_to_gain(float db)
+{
+   return powf(10.0f, db / 20.0f);
+}
+
 #ifdef GEKKO
 #include <unistd.h>
 #endif

retroarch.c

@@ -368,7 +368,8 @@ static bool audio_flush(const int16_t *data, size_t samples)
    struct resampler_data src_data = {0};
    RARCH_PERFORMANCE_INIT(audio_convert_s16);
    RARCH_PERFORMANCE_START(audio_convert_s16);
-   audio_convert_s16_to_float(g_extern.audio_data.data, data, samples);
+   audio_convert_s16_to_float(g_extern.audio_data.data, data, samples,
+         g_extern.audio_data.volume_gain);
    RARCH_PERFORMANCE_STOP(audio_convert_s16);
 
 #if defined(HAVE_DYLIB)
@@ -2405,6 +2406,37 @@ static void check_mute(void)
 
    old_pressed = pressed;
 }
+
+static void check_volume(void)
+{
+   if (!g_extern.audio_active)
+      return;
+
+   float db_change   = 0.0f;
+   bool pressed_up   = input_key_pressed_func(RARCH_VOLUME_UP);
+   bool pressed_down = input_key_pressed_func(RARCH_VOLUME_DOWN);
+   if (!pressed_up && !pressed_down)
+      return;
+
+   if (pressed_up)
+      db_change += 0.5f;
+   if (pressed_down)
+      db_change -= 0.5f;
+
+   g_extern.audio_data.volume_db += db_change;
+   if (g_extern.audio_data.volume_db > 12.0f)
+      g_extern.audio_data.volume_db = 12.0f;
+   else if (g_extern.audio_data.volume_db < -80.0f)
+      g_extern.audio_data.volume_db = -80.0f;
+
+   char msg[256];
+   snprintf(msg, sizeof(msg), "Volume: %.1f dB", g_extern.audio_data.volume_db);
+   msg_queue_clear(g_extern.msg_queue);
+   msg_queue_push(g_extern.msg_queue, msg, 1, 180);
+   RARCH_LOG("%s\n", msg);
+
+   g_extern.audio_data.volume_gain = db_to_gain(g_extern.audio_data.volume_db);
+}
 #endif
 
 #ifdef HAVE_NETPLAY
@@ -2441,6 +2473,7 @@ static void do_state_checks(void)
 #endif
 #if !defined(RARCH_PERFORMANCE_MODE)
    check_mute();
+   check_volume();
 #endif
 
    check_turbo();

retroarch.cfg

@@ -186,6 +186,11 @@
 # Input rate = in_rate * (1.0 +/- audio_rate_control_delta)
 # audio_rate_control_delta = 0.005
 
+# Audio volume. Volume is expressed in dB.
+# 0 dB is normal volume. No gain will be applied.
+# Gain can be controlled in runtime with input_volume_up/input_volume_down.
+# audio_volume = 0.0
+
 #### Input
 
 # Input driver. Depending on video driver, it might force a different input driver.
@@ -352,6 +357,11 @@
 # Alternatively, all hotkeys for keyboard could be disabled by the user.
 # input_enable_hotkey =
 
+# Increases audio volume.
+# input_volume_up = kp_plus
+# Decreases audio volume.
+# input_volume_down = kp_minus
+
 #### Misc
 
 # Enable rewinding. This will take a performance hit when playing, so it is disabled by default.

settings.c

@@ -200,6 +200,7 @@ void config_set_defaults(void)
    g_settings.audio.sync = audio_sync;
    g_settings.audio.rate_control = rate_control;
    g_settings.audio.rate_control_delta = rate_control_delta;
+   g_settings.audio.volume = audio_volume;
 
    g_settings.rewind_enable = rewind_enable;
    g_settings.rewind_buffer_size = rewind_buffer_size;
@@ -514,6 +515,7 @@ bool config_load_file(const char *path)
    CONFIG_GET_BOOL(audio.sync, "audio_sync");
    CONFIG_GET_BOOL(audio.rate_control, "audio_rate_control");
    CONFIG_GET_FLOAT(audio.rate_control_delta, "audio_rate_control_delta");
+   CONFIG_GET_FLOAT(audio.volume, "audio_volume");
 
    CONFIG_GET_STRING(video.driver, "video_driver");
    CONFIG_GET_STRING(audio.driver, "audio_driver");
@@ -670,6 +672,8 @@ static const struct bind_map bind_maps[MAX_PLAYERS][RARCH_BIND_LIST_END_NULL] =
       DECLARE_BIND(netplay_flip_players,  RARCH_NETPLAY_FLIP),
       DECLARE_BIND(slowmotion,            RARCH_SLOWMOTION),
       DECLARE_BIND(enable_hotkey,         RARCH_ENABLE_HOTKEY),
+      DECLARE_BIND(volume_up,             RARCH_VOLUME_UP),
+      DECLARE_BIND(volume_down,           RARCH_VOLUME_DOWN),
    },
 
    { DECL_PLAYER(2) },

tools/retroarch-joyconfig.c

@@ -120,6 +120,8 @@ static struct bind binds[] = {
    MISC_BIND("Netplay player flip", netplay_flip_players),
    MISC_BIND("Slow motion", slowmotion),
    MISC_BIND("Hotkey enable", enable_hotkey),
+   MISC_BIND("Volume up", volume_up),
+   MISC_BIND("Volume down", volume_down),
 };
 
 #define MAX_BUTTONS 32