Lowered FluidSynth's default gain, and added config file and command-line

options to specify it. FluidSynth's gain ranges from 0.0 through 10.0 and
is probably measured in decibel, but to keep things simple, ScummVM uses
settings from 0 through 1000 instead. (Though currently there's no guard
against invalid settings.)

This is a slightly revised version of the non-GUI part of patch #1336171.

svn-id: r20030

7 files changed, 43 insertions, 5 deletions

diff --git a/NEWS b/NEWS
index 33919199d6..20f2b92d7d 100644
--- a/NEWS
+++ b/NEWS
@@ -24,6 +24,7 @@ For a more comprehensive changelog for the latest experimental CVS code, see:
      cannot use it.
    - Fixed potential security vulnerability with oversized PATH environment
      variables.
+   - Lowered default gain for FluidSynth and made it configurable.
 
  SCUMM:
    - Fixed mouse button states in COMI.
diff --git a/README b/README
index 871de440d9..ae5a04eb03 100644
--- a/README
+++ b/README
@@ -469,7 +469,9 @@ arguments - see the next section.
   -q, --language=LANG      Select language (see also section 5.2)
   -m, --music-volume=NUM   Set the music volume, 0-255 (default: 192)
   -s, --sfx-volume=NUM     Set the sfx volume, 0-255 (default: 192)
-  -r, --speech-volume=NUM   Set the voice volume, 0-255 (default: 192)
+  -r, --speech-volume=NUM  Set the voice volume, 0-255 (default: 192)
+  --midi-gain=NUM          Set the gain for MIDI playback, 0-1000 (default:100)
+                           (only supported by some MIDI drivers)
   -n, --subtitles          Enable subtitles (use with games that have voice)
   -b, --boot-param=NUM     Pass number to the boot script (boot param)
   -d, --debuglevel=NUM     Set debug verbosity level
@@ -865,6 +867,15 @@ If ScummVM was build with libfluildsynth support it will be able to play MIDI
 music through the FluidSynth driver. You will have to specify a SoundFont to
 use, however.
 
+Since the default output volume from FluidSynth can be fairly low, ScummVM will
+set the gain by default to get a stronger signal. This can be further adjusted
+using the --midi-gain command-line option, or the "midi_gain" config file
+setting.
+
+The setting can take any value from 0 through 1000, with the default being 100.
+(This corresponds to FluidSynth's gain settings of 0.0 through 10.0, which are
+presumably measured in decibel.)
+
 NOTE: The processor requirements for FluidSynth can be fairly high in some
 cases. A fast CPU is recommended.
 
@@ -1269,6 +1280,8 @@ The following keywords are recognized:
         sfx_volume      number   The sfx volume setting (0-255)
         tempo           number   The music tempo (50-200) (default: 100)
         speech_volume   number   The speech volume setting (0-255)
+        midi_gain       number   The MIDI gain (0-1000) (default: 100) (Only
+                                 suported by some MIDI drivers.)
 
         copy_protection bool     Enable copy protection in SCUMM games, when
                                  ScummVM disables it by default.
diff --git a/base/gameDetector.cpp b/base/gameDetector.cpp
index 3ae7698eee..0444f164e2 100644
--- a/base/gameDetector.cpp
+++ b/base/gameDetector.cpp
@@ -73,6 +73,8 @@ static const char USAGE_STRING[] =
 	"  -m, --music-volume=NUM   Set the music volume, 0-255 (default: 192)\n"
 	"  -s, --sfx-volume=NUM     Set the sfx volume, 0-255 (default: 192)\n"
 	"  -r, --speech-volume=NUM  Set the speech volume, 0-255 (default: 192)\n"
+	"  --midi-gain=NUM          Set the gain for MIDI playback, 0-1000 (default:\n"
+        "                           100) (only supported by some MIDI drivers)\n"
 	"  -n, --subtitles          Enable subtitles (use with games that have voice)\n"
 	"  -b, --boot-param=NUM     Pass number to the boot script (boot param)\n"
 	"  -d, --debuglevel=NUM     Set debug verbosity level\n"
@@ -132,11 +134,12 @@ GameDetector::GameDetector() {
 	ConfMan.registerDefault("multi_midi", false);
 	ConfMan.registerDefault("native_mt32", false);
 	ConfMan.registerDefault("enable_gs", false);
+	ConfMan.registerDefault("midi_gain", 100);
 //	ConfMan.registerDefault("music_driver", ???);
 
 	ConfMan.registerDefault("cdrom", 0);
 
-	// Game specifc
+	// Game specific
 	ConfMan.registerDefault("path", "");
 	ConfMan.registerDefault("savepath", "");
 
@@ -459,6 +462,10 @@ void GameDetector::parseCommandLine(int argc, char **argv) {
 				settings["speech_volume"] = option;
 			END_OPTION
 
+			DO_LONG_OPTION_INT("midi-gain")
+				settings["midi_gain"] = option;
+			END_OPTION
+
 			DO_OPTION_CMD('t', "list-targets")
 				listTargets();
 				exit(0);
diff --git a/doc/05_01.tex b/doc/05_01.tex
index 9b40d81115..220bfad68c 100644
--- a/doc/05_01.tex
+++ b/doc/05_01.tex
@@ -22,6 +22,8 @@ Usage: scummvm [OPTIONS]... [GAME]\\
   -m, --music-volume=NUM  &Set the music volume, 0-255 (default: 192)\\
   -s, --sfx-volume=NUM    &Set the sfx volume, 0-255 (default: 192)\\
   -r, --speech-volume=NUM  &Set the voice volume, 0-255 (default: 192)\\
+  --midi-gain             &Set the gain for MIDI playback, 0-1000 (default:\\
+                          &100) (only supported by some MIDI drivers)\\
   -n, --subtitles         &Enable subtitles (use with games that have voice)\\
   -b, --boot-param=NUM    &Pass number to the boot script (boot param)\\
   -d, --debuglevel=NUM    &Set debug verbosity level\\
diff --git a/doc/07_02b.tex b/doc/07_02b.tex
index 8c9c22c9aa..4acc95ae2d 100644
--- a/doc/07_02b.tex
+++ b/doc/07_02b.tex
@@ -10,5 +10,14 @@ If ScummVM was build with libfluildsynth support it will be able to play MIDI
 music through the FluidSynth driver. You will have to specify a SoundFont to
 use, however.
 
+Since the default output volume from FluidSynth can be fairly low, ScummVM will
+set the gain by default to get a stronger signal. This can be further adjusted
+using the --midi-gain command-line option, or the ``midi\_gain'' config file
+setting.
+
+The setting can take any value from 0 through 1000, with the default being 100.
+(This corresponds to FluidSynth's gain settings of 0.0 through 10.0, which are
+presumably measured in decibel.)
+
 \textbf{NOTE:} The processor requirements for FluidSynth can be fairly high in
 some cases. A fast CPU is recommended.
diff --git a/doc/08.tex b/doc/08.tex
index 7bde403612..461eee6de4 100644
--- a/doc/08.tex
+++ b/doc/08.tex
@@ -109,6 +109,8 @@ The following keywords are recognized:
         sfx\_volume     &number   The sfx volume setting (0-255)\\
         tempo           &number   The music tempo (50-200) (default: 100)\\
         speech\_volume  &number   The speech volume setting (0-255)\\
+        midi\_gain      &number   The MIDI gain (0-1000) (default: 100) (Only\\
+                        &         supported by some MIDI drivers.)\\
 \\
         copy\_protection&bool     Enable copy protection in SCUMM games, when\\
                         &         ScummVM disables it by default.\\
diff --git a/sound/softsynth/fluidsynth.cpp b/sound/softsynth/fluidsynth.cpp
index a3aaab3bcb..e0ded4596f 100644
--- a/sound/softsynth/fluidsynth.cpp
+++ b/sound/softsynth/fluidsynth.cpp
@@ -114,10 +114,14 @@ int MidiDriver_FluidSynth::open() {
 
 	_settings = new_fluid_settings();
 
-	// The default gain setting is ridiculously low, but we can't set it
-	// too high either or sound will be clipped. This may need tuning...
+	// The default gain setting is ridiculously low - at least for me. This
+	// cannot be fixed by ScummVM's volume settings because they can only
+	// soften the sound, not amplify it, so instead we add an option to
+	// adjust the gain of FluidSynth itself.
 
-	setNum("synth.gain", 2.1);
+	double gain = (double)ConfMan.getInt("midi_gain") / 100.0;
+
+	setNum("synth.gain", gain);
 	setNum("synth.sample-rate", _outputRate);
 
 	_synth = new_fluid_synth(_settings);