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winmm: Preserve fractions in microseconds to compensate rounding errors. 

Otherwise, a song is played faster than expected in some cases.

For instance, we assume that 40 pan control change (CC#10) messages are
expressed in 12.5ms each,
 * Prior art omits fractions, i.e. 12ms + 12ms + ... = 480ms.
 * Proposal technique saves fractions, i.e. 12ms + 13ms + ... = 500ms.
Ideal duration is 500ms. So, the proposed method is better than prior one.

Signed-off-by: Akihiro Sagawa <sagawa.aki@gmail.com>
Signed-off-by: Andrew Eikum <aeikum@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Akihiro Sagawa 2018-06-26 22:10:47 +09:00 committed by Alexandre Julliard
parent 2cb326260b
commit 381012f75d
1 changed files with 11 additions and 4 deletions
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15
dlls/winmm/winmm.c
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@ -921,6 +921,7 @@ typedef struct WINE_MIDIStream {
DWORD dwElapsedMS;
WORD wFlags;
WORD status;
WORD remainder;
HANDLE hEvent;
LPMIDIHDR lpMidiHdr;
} WINE_MIDIStream;
@ -965,13 +966,13 @@ static DWORD MMSYSTEM_MidiStream_Convert(WINE_MIDIStream* lpMidiStrm, DWORD puls
} else if (lpMidiStrm->dwTimeDiv > 0x8000) { /* SMPTE, unchecked FIXME? */
int nf = 256 - HIBYTE(lpMidiStrm->dwTimeDiv); /* number of frames */
int nsf = LOBYTE(lpMidiStrm->dwTimeDiv); /* number of sub-frames */
ret = (pulse * 1000) / (nf * nsf);
ret = (pulse * 1000000) / (nf * nsf);
} else {
ret = (DWORD)((double)pulse * ((double)lpMidiStrm->dwTempo / 1000) /
ret = (DWORD)((double)pulse * (double)lpMidiStrm->dwTempo /
(double)lpMidiStrm->dwTimeDiv);
}
return ret;
return ret; /* in microseconds */
}
static DWORD midistream_get_playing_position(WINE_MIDIStream* lpMidiStrm)
@ -1007,6 +1008,8 @@ static BOOL MMSYSTEM_MidiStream_MessageHandler(WINE_MIDIStream* lpMidiStrm, LPWI
lpMidiStrm->status = MSM_STATUS_STOPPED;
lpMidiStrm->dwPulses = 0;
lpMidiStrm->dwElapsedMS = 0;
lpMidiStrm->dwPositionMS = 0;
lpMidiStrm->remainder = 0;
LeaveCriticalSection(&lpMidiStrm->lock);
/* this is not quite what MS doc says... */
midiOutReset(lpMidiStrm->hDevice);
@ -1178,8 +1181,11 @@ start_header:
/* do we have to wait ? */
if (me->dwDeltaTime) {
DWORD delta;
EnterCriticalSection(&lpMidiStrm->lock);
lpMidiStrm->dwPositionMS += MMSYSTEM_MidiStream_Convert(lpMidiStrm, me->dwDeltaTime);
delta = lpMidiStrm->remainder + MMSYSTEM_MidiStream_Convert(lpMidiStrm, me->dwDeltaTime);
lpMidiStrm->dwPositionMS += delta / 1000;
lpMidiStrm->remainder = delta % 1000;
lpMidiStrm->dwPulses += me->dwDeltaTime;
LeaveCriticalSection(&lpMidiStrm->lock);
@ -1331,6 +1337,7 @@ MMRESULT WINAPI midiStreamOpen(HMIDISTRM* lphMidiStrm, LPUINT lpuDeviceID,
lpMidiStrm->dwTempo = 500000; /* micro seconds per quarter note, i.e. 120 BPM */
lpMidiStrm->dwTimeDiv = 24; /* ticks per quarter note */
lpMidiStrm->dwPositionMS = 0;
lpMidiStrm->remainder = 0;
lpMidiStrm->status = MSM_STATUS_PAUSED;
lpMidiStrm->dwElapsedMS = 0;