M CHANGES → CHANGES

@@ -62,6 +62,7 @@ - Qt: Fix LOG argument order
  - Qt: Fix timezone issues with time overrides
  - Qt: Fix sprite export pausing game indefinitely (fixes mgba.io/i/841)
  - SDL: Fix potential race condition when pressing keys (fixes mgba.io/i/872)
+ - GB Audio: Make audio unsigned with bias (fixes mgba.io/i/749)
 Misc:
  - CMake: Fix CPack dependencies for libpng 1.6
  - GBA: Detect hardware for Pokémon FireRed ROM hacks

M src/gb/audio.c → src/gb/audio.c

@@ -620,8 +620,9 @@ sampleRight += audio->ch4.sample;
 		}
 	}
 
-	*left = sampleLeft * (1 + audio->volumeLeft);
-	*right = sampleRight * (1 + audio->volumeRight);
+	int dcOffset = audio->style == GB_AUDIO_GBA ? 0 : 0x1FC;
+	*left = (sampleLeft - dcOffset) * (1 + audio->volumeLeft);
+	*right = (sampleRight - dcOffset) * (1 + audio->volumeRight);
 }
 
 static void _sample(struct mTiming* timing, void* user, uint32_t cyclesLate) {
@@ -709,7 +710,7 @@ return (envelope->initialVolume || envelope->direction) && envelope->dead != 2;
 }
 
 static void _updateSquareSample(struct GBAudioSquareChannel* ch) {
-	ch->sample = (ch->control.hi * 2 - 1) * ch->envelope.currentVolume * 0x8;
+	ch->sample = ch->control.hi * ch->envelope.currentVolume * 0x8;
 }
 
 static int32_t _updateSquareChannel(struct GBAudioSquareChannel* ch) {
@@ -860,8 +861,7 @@ }
 		ch->sample = bitsCarry >> 4;
 		break;
 	}
-	ch->sample -= 8;
-	ch->sample *= volume * 4;
+	ch->sample *= volume * 2;
 	audio->ch3.readable = true;
 	if (audio->style == GB_AUDIO_DMG) {
 		mTimingDeschedule(audio->timing, &audio->ch3Fade);
@@ -888,7 +888,7 @@ int32_t cycles = 0;
 
 	do {
 		int lsb = ch->lfsr & 1;
-		ch->sample = lsb * 0x10 - 0x8;
+		ch->sample = lsb * 0x8;
 		ch->sample *= ch->envelope.currentVolume;
 		ch->lfsr >>= 1;
 		ch->lfsr ^= (lsb * 0x60) << (ch->power ? 0 : 8);