diff options
| -rw-r--r-- | src/mixer.cpp | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/src/mixer.cpp b/src/mixer.cpp index b4ea66994..3e9b1c5cb 100644 --- a/src/mixer.cpp +++ b/src/mixer.cpp @@ -5,6 +5,7 @@ #include "stdafx.h" #include "openttd.h" #include "mixer.h" +#include "core/math_func.hpp" struct MixerChannel { bool active; @@ -19,8 +20,8 @@ struct MixerChannel { uint32 samples_left; /* Mixing volume */ - uint volume_left; - uint volume_right; + int volume_left; + int volume_right; uint flags; }; @@ -28,14 +29,22 @@ struct MixerChannel { static MixerChannel _channels[8]; static uint32 _play_rate; +/** + * The theoretical maximum volume for a single sound sample. Multiple sound + * samples should not exceed this limit as it will sound too loud. It also + * stops overflowing when too many sounds are played at the same time, which + * causes an even worse sound quality. + */ +static const int MAX_VOLUME = 128 * 128; + static void mix_int8_to_int16(MixerChannel *sc, int16 *buffer, uint samples) { int8 *b; uint32 frac_pos; uint32 frac_speed; - uint volume_left; - uint volume_right; + int volume_left; + int volume_right; if (samples > sc->samples_left) samples = sc->samples_left; sc->samples_left -= samples; @@ -50,15 +59,15 @@ static void mix_int8_to_int16(MixerChannel *sc, int16 *buffer, uint samples) if (frac_speed == 0x10000) { /* Special case when frac_speed is 0x10000 */ do { - buffer[0] += *b * volume_left >> 8; - buffer[1] += *b * volume_right >> 8; + buffer[0] = Clamp(buffer[0] + (*b * volume_left >> 8), -MAX_VOLUME, MAX_VOLUME); + buffer[0] = Clamp(buffer[1] + (*b * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME); b++; buffer += 2; } while (--samples > 0); } else { do { - buffer[0] += *b * volume_left >> 8; - buffer[1] += *b * volume_right >> 8; + buffer[0] = Clamp(buffer[0] + (*b * volume_left >> 8), -MAX_VOLUME, MAX_VOLUME); + buffer[0] = Clamp(buffer[1] + (*b * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME); buffer += 2; frac_pos += frac_speed; b += frac_pos >> 16; |