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- So, apparently the XMIDI library uses a fixed 120 Hz clock for MIDI events. As a result, we

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should ignore any tempo events in XMIDI songs that were left over from the original MIDI
  files, since the converter didn't remove them.

SVN r3384 (trunk)
This commit is contained in:
Randy Heit 2012-02-23 02:22:56 +00:00
parent c3dba9ca9a
commit 9457a1b3f8
2 changed files with 15 additions and 69 deletions
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1
src/sound/i_musicinterns.h
View file

@ -637,7 +637,6 @@ protected:
int FindXMIDforms(const BYTE *chunk, int len, TrackInfo *songs) const;
void FoundXMID(const BYTE *chunk, int len, TrackInfo *song) const;
void ScanForTempo(const TrackInfo *song);
bool SetMIDISubsong(int subsong);
void DoInitialSetup();
void DoRestart();

83
src/sound/music_xmi_midiout.cpp
View file

@ -134,16 +134,22 @@ XMISong::XMISong (FILE *file, BYTE *musiccache, int len, EMidiDevice type)
{
return;
}
// The division is the number of pulses per quarter note (PPQN).
// It is set by a specific MIDI event, but just in case these aren't used,
// set a default value. Specs indicate it should be 120.
Division = 120;
// XMIDI files are played with a constant 120 Hz clock rate. While the
// song may contain tempo events, these are vestigial remnants from the
// original MIDI file that were not removed by the converter and should
// be ignored.
//
// We can use any combination of Division and Tempo values that work out
// to be 120 Hz.
Division = 60;
InitialTempo = 500000;
Songs = new TrackInfo[NumSongs];
memset(Songs, 0, sizeof(*Songs) * NumSongs);
FindXMIDforms(MusHeader, len, Songs);
CurrSong = Songs;
DPrintf("XMI song count: %d\n", NumSongs);
DPrintf("Divisions: %d\n", Division);
}
//==========================================================================
@ -237,37 +243,6 @@ void XMISong::FoundXMID(const BYTE *chunk, int len, TrackInfo *song) const
}
}
//==========================================================================
//
// XMISong :: ScanForTempo
//
// Look through events chunk to find one that sets the tempo.
//
//==========================================================================
void XMISong::ScanForTempo(const TrackInfo *song)
{
const BYTE *chunk = song->EventChunk;
for (size_t q = 0; q < song->EventLen - 3; )
{
int r = q;
int evmark = chunk[r];
int evtype = chunk[r + 1];
int evlen = chunk[r + 2];
// Is it a tempo event? If so, length should be 3.
if (evmark == MIDI_META && evtype == MIDI_META_TEMPO && evlen == 3)
{
// Tempo is given in microseconds per quarter notes, so for a base of
// 120 per second, we have to divide by a million a multiply by 120 to
// get the PPQN. This is simplified by 40 to manipulate smaller values.
Tempo = (chunk[r + 3] << 16) | (chunk[r + 4] << 8) | chunk[r + 5];
Division = Tempo * 3 / 25000;
}
q += 3 + evlen;
}
}
//==========================================================================
//
// XMISong :: SetMIDISubsong
@ -562,23 +537,9 @@ DWORD *XMISong::SendCommand (DWORD *events, EventSource due, DWORD delay)
if (track->EventP + len <= track->EventLen)
{
switch (event)
if (event == MIDI_META_EOT)
{
case MIDI_META_EOT:
track->Finished = true;
break;
case MIDI_META_TEMPO:
Tempo =
(track->EventChunk[track->EventP+0]<<16) |
(track->EventChunk[track->EventP+1]<<8) |
(track->EventChunk[track->EventP+2]);
events[0] = delay;
events[1] = 0;
events[2] = (MEVT_TEMPO << 24) | Tempo;
events += 3;
Division = Tempo * 3 / 25000;
break;
}
track->EventP += len;
if (track->EventP == track->EventLen)
@ -615,28 +576,14 @@ void XMISong::ProcessInitialMetaEvents ()
while (!track->Finished &&
track->EventP < track->EventLen - 3 &&
track->EventChunk[track->EventP] == 0xFF)
track->EventChunk[track->EventP] == MIDI_META)
{
event = track->EventChunk[track->EventP+1];
track->EventP += 2;
len = track->ReadVarLen();
if (track->EventP + len <= track->EventLen)
if (track->EventP + len <= track->EventLen && event == MIDI_META_EOT)
{
switch (event)
{
case MIDI_META_EOT:
track->Finished = true;
break;
case MIDI_META_TEMPO:
SetTempo(
(track->EventChunk[track->EventP+0]<<16) |
(track->EventChunk[track->EventP+1]<<8) |
(track->EventChunk[track->EventP+2])
);
Division = Tempo * 3 / 25000;
break;
}
track->Finished = true;
}
track->EventP += len;
}