sound: make the compressor optional (clamp overdrive to -1.0-1.0 when off)

docs/man/mame.6

@@ -938,6 +938,9 @@ cause higher audio quality but slower emulation speed. The default is
 .B \-[no]samples
 Use samples if available. The default is ON (\-samples).
 .TP
+.B \-[no]compressor
+Use compressor for sound. The default is ON (\-compressor).
+.TP
 .B \-volume, \-vol \fIvalue
 Sets the startup volume. It can later be changed with the user interface
 (see Keys section). The volume is an attenuation in dB: e.g.,

docs/man/mess.6

@@ -969,6 +969,9 @@ cause higher audio quality but slower emulation speed. The default is
 .B \-[no]samples
 Use samples if available. The default is ON (\-samples).
 .TP
+.B \-[no]compressor
+Use compressor for sound. The default is ON (\-compressor).
+.TP
 .B \-volume, \-vol \fIvalue
 Sets the startup volume. It can later be changed with the user interface
 (see Keys section). The volume is an attenuation in dB:

docs/source/commandline/commandline-all.rst

@@ -2824,6 +2824,19 @@ Core Sound Options
 
             mame qbert -nosamples
 
+.. _mame-commandline-nocompressor:
+
+**-[no]compressor**
+
+    Use compressor for sound.
+
+    The default is ON (**-compressor**).
+
+    Example:
+        .. code-block:: bash
+
+            mame popeye -nocompressor
+
 .. _mame-commandline-volume:
 
 **-volume** / **-vol** *<value>*

docs/source/commandline/commandline-index.rst

@@ -237,9 +237,9 @@ Core Video OpenGL GLSL Options
 Core Sound Options
 ~~~~~~~~~~~~~~~~~~
 
-
 | :ref:`samplerate <mame-commandline-samplerate>`
 | :ref:`[no]samples <mame-commandline-nosamples>`
+| :ref:`[no]compressor <mame-commandline-nocompressor>`
 | :ref:`volume <mame-commandline-volume>`
 | :ref:`sound <mame-commandline-sound>`
 | :ref:`audio_latency <mame-commandline-audiolatency>`

src/emu/emuopts.cpp

@@ -141,7 +141,8 @@ const options_entry emu_options::s_option_entries[] =
 	{ OPTION_SAMPLERATE ";sr(1000-1000000)",             "48000",     OPTION_INTEGER,    "set sound output sample rate" },
 	{ OPTION_SAMPLES,                                    "1",         OPTION_BOOLEAN,    "enable the use of external samples if available" },
 	{ OPTION_VOLUME ";vol",                              "0",         OPTION_INTEGER,    "sound volume in decibels (-32 min, 0 max)" },
-	{ OPTION_SPEAKER_REPORT,                             "0",         OPTION_INTEGER,    "print report of speaker ouput maxima (0=none, or 1-4 for more detail)" },
+	{ OPTION_COMPRESSOR,                                 "1",         OPTION_BOOLEAN,    "enable compressor for sound" },
+	{ OPTION_SPEAKER_REPORT "(0-4)",                     "0",         OPTION_INTEGER,    "print report of speaker ouput maxima (0=none, or 1-4 for more detail)" },
 
 	// input options
 	{ nullptr,                                           nullptr,     OPTION_HEADER,     "CORE INPUT OPTIONS" },

src/emu/emuopts.h

@@ -120,6 +120,7 @@
 #define OPTION_SAMPLERATE           "samplerate"
 #define OPTION_SAMPLES              "samples"
 #define OPTION_VOLUME               "volume"
+#define OPTION_COMPRESSOR           "compressor"
 #define OPTION_SPEAKER_REPORT       "speaker_report"
 
 // core input options
@@ -405,6 +406,7 @@ public:
 	int sample_rate() const { return int_value(OPTION_SAMPLERATE); }
 	bool samples() const { return bool_value(OPTION_SAMPLES); }
 	int volume() const { return int_value(OPTION_VOLUME); }
+	bool compressor() const { return bool_value(OPTION_COMPRESSOR); }
 	int speaker_report() const { return int_value(OPTION_SPEAKER_REPORT); }
 
 	// core input options

src/emu/sound.cpp

@@ -1068,6 +1068,7 @@ sound_manager::sound_manager(running_machine &machine) :
 	m_rightmix(machine.sample_rate()),
 	m_compressor_scale(1.0),
 	m_compressor_counter(0),
+	m_compressor_enabled(machine.options().compressor()),
 	m_muted(0),
 	m_nosound_mode(machine.osd().no_sound()),
 	m_attenuation(0),
@@ -1543,8 +1544,11 @@ void sound_manager::update(void *ptr, int param)
 		if (lscale != m_compressor_scale && sample != m_finalmix_leftover)
 			lscale = adjust_toward_compressor_scale(lscale, lprev, lsamp);
 
+		lprev = lsamp * lscale;
+		if (m_compressor_enabled)
+			lsamp = lprev;
+
 		// clamp the left side
-		lprev = lsamp *= lscale;
 		if (lsamp > 1.0)
 			lsamp = 1.0;
 		else if (lsamp < -1.0)
@@ -1556,8 +1560,11 @@ void sound_manager::update(void *ptr, int param)
 		if (rscale != m_compressor_scale && sample != m_finalmix_leftover)
 			rscale = adjust_toward_compressor_scale(rscale, rprev, rsamp);
 
-		// clamp the left side
+		rprev = rsamp * rscale;
-		rprev = rsamp *= rscale;
+		if (m_compressor_enabled)
+			rsamp = rprev;
+
+		// clamp the right side
 		if (rsamp > 1.0)
 			rsamp = 1.0;
 		else if (rsamp < -1.0)

src/emu/sound.h

@@ -833,6 +833,7 @@ private:
 
 	stream_buffer::sample_t m_compressor_scale; // current compressor scale factor
 	int m_compressor_counter;             // compressor update counter for backoff
+	bool m_compressor_enabled;            // enable compressor (it will still be calculated for detecting overdrive)
 
 	u8 m_muted;                           // bitmask of muting reasons
 	bool m_nosound_mode;                  // true if we're in "nosound" mode

src/frontend/mame/ui/sndmenu.cpp

@@ -28,6 +28,7 @@ menu_sound_options::menu_sound_options(mame_ui_manager &mui, render_container &c
 	m_sample_rate = mui.machine().options().sample_rate();
 	m_sound = (strcmp(options.sound(), OSDOPTVAL_NONE) && strcmp(options.sound(), "0"));
 	m_samples = mui.machine().options().samples();
+	m_compressor = mui.machine().options().compressor();
 
 	int total = std::size(m_sound_rate);
 
@@ -51,6 +52,10 @@ menu_sound_options::~menu_sound_options()
 	{
 		moptions.set_value(OSDOPTION_SOUND, m_sound ? OSDOPTVAL_AUTO : OSDOPTVAL_NONE, OPTION_PRIORITY_CMDLINE);
 	}
+	if (moptions.bool_value(OPTION_COMPRESSOR) != m_compressor)
+	{
+		moptions.set_value(OPTION_COMPRESSOR, m_compressor, OPTION_PRIORITY_CMDLINE);
+	}
 	if (moptions.int_value(OPTION_SAMPLERATE) != m_sound_rate[m_cur_rates])
 	{
 		moptions.set_value(OPTION_SAMPLERATE, m_sound_rate[m_cur_rates], OPTION_PRIORITY_CMDLINE);
@@ -84,6 +89,14 @@ void menu_sound_options::handle()
 			}
 			break;
 
+		case ENABLE_COMPRESSOR:
+			if (menu_event->iptkey == IPT_UI_LEFT || menu_event->iptkey == IPT_UI_RIGHT || menu_event->iptkey == IPT_UI_SELECT)
+			{
+				m_compressor = !m_compressor;
+				changed = true;
+			}
+			break;
+
 		case SAMPLE_RATE:
 			if (menu_event->iptkey == IPT_UI_LEFT || menu_event->iptkey == IPT_UI_RIGHT)
 			{
@@ -133,6 +146,7 @@ void menu_sound_options::populate(float &customtop, float &custombottom)
 
 	// add options items
 	item_append_on_off(_("Sound"), m_sound, 0, (void *)(uintptr_t)ENABLE_SOUND);
+	item_append_on_off(_("Compressor"), m_compressor, 0, (void *)(uintptr_t)ENABLE_COMPRESSOR);
 	item_append(_("Sample Rate"), string_format("%d", m_sample_rate), arrow_flags, (void *)(uintptr_t)SAMPLE_RATE);
 	item_append_on_off(_("Use External Samples"), m_samples, 0, (void *)(uintptr_t)ENABLE_SAMPLES);
 	item_append(menu_item_type::SEPARATOR);

src/frontend/mame/ui/sndmenu.h

@@ -32,6 +32,7 @@ private:
 	enum
 	{
 		ENABLE_SOUND = 1,
+		ENABLE_COMPRESSOR,
 		SAMPLE_RATE,
 		ENABLE_SAMPLES
 	};
@@ -42,7 +43,7 @@ private:
 	uint16_t          m_cur_rates;
 	static const int  m_sound_rate[];
 	int               m_sample_rate;
-	bool              m_samples, m_sound;
+	bool              m_samples, m_sound, m_compressor;
 };
 
 } // namespace ui