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KYRA: (LOK) - fix AdLib sound glitch (bug #11303)

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This commit is contained in:
athrxx 2020-01-18 00:05:26 +01:00
parent d31b4e4f37
commit 12fd8cd45a
1 changed files with 22 additions and 4 deletions
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26
engines/kyra/sound/drivers/adlib.cpp
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@ -934,13 +934,26 @@ uint8 AdLibDriver::calculateOpLevel1(Channel &channel) {
value += level3 ^ 0x3F;
}
value = CLIP<int8>(value, 0, 0x3F);
// The clipping as signed instead of unsigned causes very ugly noises in LOK when the music
// is fading out in certain situations (bug #11303). The bug only comes to surface when the
// volume setting is not maxed out to 255.
// The original LOK AdLib driver does the same wrong clipping, but this doesn't cause glitches
// there. The original driver (and game) does not have volume settings and uses a simpler
// total level calculation (simply adding the three opExtraLevels to the opLevel).
// The original HOF/LOL sound drivers do the same clipping, too. That's were we got that code.
// I assume that the issue has been fixed in the fadeout tracks there.
// I limit this to LOK for now, since the issue hasn't been reported from any other KYRA games.
if (_version == 3) {
if (value < 0)
debugC(3, kDebugLevelSound, "AdLibDriver::calculateOpLevel1(): WORKAROUND - total level clipping uint/int bug encountered");
value = (int8)CLIP<uint8>(value, 0, 0x3F);
} else
value = CLIP<int8>(value, 0, 0x3F);
if (!channel.volumeModifier)
value = 0x3F;
// Preserve the scaling level bits from opLevel1
return checkValue(value) | (channel.opLevel1 & 0xC0);
}
@ -958,13 +971,18 @@ uint8 AdLibDriver::calculateOpLevel2(Channel &channel) {
value += level3 ^ 0x3F;
value = CLIP<int8>(value, 0, 0x3F);
// See comment in calculateOpLevel1()
if (_version == 3) {
if (value < 0)
debugC(3, kDebugLevelSound, "AdLibDriver::calculateOpLevel1(): WORKAROUND - total level clipping uint/int bug encountered");
value = (int8)CLIP<uint8>(value, 0, 0x3F);
} else
value = CLIP<int8>(value, 0, 0x3F);
if (!channel.volumeModifier)
value = 0x3F;
// Preserve the scaling level bits from opLevel2
return checkValue(value) | (channel.opLevel2 & 0xC0);
}