[Scummvm-tracker] [ScummVM :: Bugs] #13460: SCUMM: DOTT: Incorrect MIDI pitch bending

[ScummVM :: Bugs]

#13460: SCUMM: DOTT: Incorrect MIDI pitch bending
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Reporter:  AndywinXp  |       Owner:  (none)
    Type:  defect     |      Status:  new
Priority:  normal     |   Component:  Engine: SCUMM
 Version:             |  Resolution:
Keywords:  adlib      |        Game:  Day of the Tentacle
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Comment (by AndywinXp):

 Okay, I lazily reversed what happens on Aaron Giles' interpreter (which
 uses General MIDI):

 These two functions appear to be called constantly during the bird event
 (forgive the names, I'm directly using my mapped function names, and I'm
 just putting the relevant parameters in):
 {{{
 IMUSE_SetTranspose(partPtr, relative, transpose) {
   uint8 clampedTranspose;

   clampedTranspose = transpose;
   if ( transpose > 24 || transpose < -24 || relative > 1 )
     return -1;
   if ( relative )
     clampedTranspose = IMUSE_UTILS_ClampTuning(transpose +
 partPtr->effTranspose, -7, 7);
   partPtr->effTranspose = clampedTranspose;
   IMUSE_PART_SetTranspose(partPtr, 16, relative, clampedTranspose);
   return 0;
 }
 }}}

 {{{
 IMUSE_SetDetune(partPtr, detune) {
   partPtr->detune = detune;
   IMUSE_PART_SetDetune(partPtr, 16, detune);
   return 0;
 }
 }}}

 These is the rest of the relevant auxiliary functions:


 {{{
 IMUSE_UTILS_ClampTuning(tuning, min, max)
 {
   if ( tuning < min )
     clampedTuning = tuning + 12 * ((min - tuning + 11) / 12);
   if ( tuning > max )
     clampedTuning = tuning - 12 * ((tuning - max + 11) / 12);

   return clampedTuning;
 }
 }}}


 {{{
 IMUSE_PART_SetTranspose(partPtr, partId, relative, transpose) {
   if ( transpose <= 24 && transpose >= -24 ) {
     if ( partId == 16 ) {
       for ( curPart = partPtr->next; curPart; curPart = curPart->next ) {
         curPart->effTranspose = IMUSE_UTILS_ClampTuning(transpose +
 curPart->transpose, -12, 12);
         IMUSE_PART_SendTranspose(curPart);
       }
     } else { /* Don't care */ }
   }
 }
 }}}

 {{{
 IMUSE_PART_SetDetune(partPtr, partId, relative, transpose) {
   if ( transpose <= 24 && transpose >= -24 ) {
     if ( partId == 16 ) {
       for ( curPart = partPtr->next; curPart ; curPart = curPart->next ) {
         curPart->effDetune = CLIP(increment + curPart->detune, -128, 127);
         IMUSE_PART_SendTranspose(curPart);
       }
     } else { /* Don't care */ }
   }
 }
 }}}

 The latter two both call this one:

 {{{
 IMUSE_PART_SendTransposeToMIDIDevice(partPtr) {
   effTranspose = clampNumber(partPtr->pitchbend + partPtr->effDetune +
 (partPtr->effTranspose * 128), -2048, 2047);

   partPtr->effTranspose = effTranspose;
   if ( partPtr->midiChannel) {
     midiPartId = midiChannel->chanNum;

     if ( midiPartsTransposeValues[midiPartId] != effTranspose ) {
       midiPartsTransposeValues[midiPartId] = effTranspose;

       // 8192 is added because this number appears to be the center
       // value for the pitchbend in this case
       sendPitchWheelValueToMIDIDevice(midiPartId, 4 *
 partPtr->effTranspose + 8192);
     }
   }
 }
 }}}

 Too tired to test it out for now, though
-- 
Ticket URL: <https://bugs.scummvm.org/ticket/13460#comment:4>
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