Add config file variable for controlling libsamplerate conversion scale

factor. This is an alternative to the approach taken in the version on
the trunk version, where all sounds are pre-converted at startup and
adjusted based on the maximum value.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2690

3 files changed, 25 insertions, 2 deletions

diff --git a/src/i_sdlsound.c b/src/i_sdlsound.c
index 4169a921..c8ec6853 100644
--- a/src/i_sdlsound.c
+++ b/src/i_sdlsound.c
@@ -88,6 +88,14 @@ static int allocated_sounds_size = 0;
 
 int use_libsamplerate = 0;
 
+// Scale factor used when converting libsamplerate floating point numbers
+// to integers. Too high means the sounds can clip; too low means they
+// will be too quiet. This is an amount that should avoid clipping most
+// of the time: with all the Doom IWAD sound effects, at least. If a PWAD
+// is used, clipping might occur.
+
+float libsamplerate_scale = 0.65;
+
 // Hook a sound into the linked list at the head.
 
 static void AllocatedSoundLink(allocated_sound_t *snd)
@@ -408,7 +416,8 @@ static boolean ExpandSoundData_SRC(sfxinfo_t *sfxinfo,
         // using INT16_MAX as the multiplier are not all that bad, but
         // artifacts are noticeable during the loudest parts.
 
-        float   cvtval_f = src_data.data_out[i] * 22265;
+        float cvtval_f =
+            src_data.data_out[i] * libsamplerate_scale * INT16_MAX;
         int32_t cvtval_i = cvtval_f + (cvtval_f < 0 ? -0.5 : 0.5);
 
         // Asymmetrical sound worries me, so we won't use -32768.
diff --git a/src/i_sound.c b/src/i_sound.c
index 47cae682..19a697d8 100644
--- a/src/i_sound.c
+++ b/src/i_sound.c
@@ -426,6 +426,7 @@ boolean I_MusicIsPlaying(void)
 void I_BindSoundVariables(void)
 {
     extern int use_libsamplerate;
+    extern float libsamplerate_scale;
 
     M_BindVariable("snd_musicdevice",   &snd_musicdevice);
     M_BindVariable("snd_sfxdevice",     &snd_sfxdevice);
@@ -442,7 +443,8 @@ void I_BindSoundVariables(void)
     M_BindVariable("gus_ram_kb",        &gus_ram_kb);
 
 #ifdef FEATURE_SOUND
-    M_BindVariable("use_libsamplerate", &use_libsamplerate);
+    M_BindVariable("use_libsamplerate",   &use_libsamplerate);
+    M_BindVariable("libsamplerate_scale", &libsamplerate_scale);
 #endif
 
     // Before SDL_mixer version 1.2.11, MIDI music caused the game
diff --git a/src/m_config.c b/src/m_config.c
index cce90579..9d421d3f 100644
--- a/src/m_config.c
+++ b/src/m_config.c
@@ -985,6 +985,18 @@ static default_t extra_defaults_list[] =
     CONFIG_VARIABLE_INT(use_libsamplerate),
 
     //!
+    // Scaling factor used by libsamplerate. This is used when converting
+    // sounds internally back into integer form; normally it should not
+    // be necessary to change it from the default value. The only time
+    // it might be needed is if a PWAD file is loaded that contains very
+    // loud sounds, in which case the conversion may cause sound clipping
+    // and the scale factor should be reduced. The lower the value, the
+    // quieter the sound effects become, so it should be set as high as is
+    // possible without clipping occurring.
+
+    CONFIG_VARIABLE_FLOAT(libsamplerate_scale),
+
+    //!
     // Full path to a Timidity configuration file to use for MIDI
     // playback. The file will be evaluated from the directory where
     // it is evaluated, so there is no need to add "dir" commands