SCUMM: (iMUSE/Amiga) - minor fixes

- At at least one place in INDY4 the game attempts to send a Roland MT-32 patch to the Amiga driver. This will fail and thus not cause any harm, but I have added a check nonetheless. The original Amiga driver ignores sysex messages that don't have the iMuse manufacturer id 7D.
- In INDY4 the iMuse player thinks it has a percussion channel due to the fact that it plays ROL resources. This should also be irrelevant for the actual playback, but I have added a check for that, too.

2 files changed, 5 insertions, 4 deletions

diff --git a/engines/scumm/imuse/imuse.cpp b/engines/scumm/imuse/imuse.cpp
index de592972aa..50a13308d8 100644
--- a/engines/scumm/imuse/imuse.cpp
+++ b/engines/scumm/imuse/imuse.cpp
@@ -241,11 +241,11 @@ bool IMuseInternal::supportsPercussion(int sound) {
 	case MKTAG('S', 'P', 'K', ' '):
 		return false;
 
-	case MKTAG('A', 'M', 'I', ' '): // Amiga
+	case MKTAG('A', 'M', 'I', ' '): // MI2 Amiga
 		return false;
 
-	case MKTAG('R', 'O', 'L', ' '):
-		return true;
+	case MKTAG('R', 'O', 'L', ' '): // Roland LAPC/MT-32/CM32L track, but also used by INDY4 Amiga
+		return !_isAmiga;
 
 	case MKTAG('M', 'A', 'C', ' '): // Occurs in the Mac version of FOA and MI2
 		// This is MIDI, i.e. uses MIDI style program changes, but without a
diff --git a/engines/scumm/imuse/imuse_player.cpp b/engines/scumm/imuse/imuse_player.cpp
index 7ec557a768..b251e153cb 100644
--- a/engines/scumm/imuse/imuse_player.cpp
+++ b/engines/scumm/imuse/imuse_player.cpp
@@ -375,7 +375,8 @@ void Player::sysEx(const byte *p, uint16 len) {
 	if (a != IMUSE_SYSEX_ID) {
 		if (a == ROLAND_SYSEX_ID) {
 			// Roland custom instrument definition.
-			if (_isMIDI || _isMT32) {
+			// There is at least one (pointless) attempt in INDY4 Amiga to send this, too.
+			if ((_isMIDI && !_se->_isAmiga) || _isMT32) {
 				part = getPart(p[0] & 0x0F);
 				if (part) {
 					part->_instrument.roland(p - 1);