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| author | Niels Martin Hansen <nielsm@indvikleren.dk> | 2018-06-06 18:20:22 +0200 |
|---|---|---|
| committer | Michael Lutz <michi@icosahedron.de> | 2018-06-15 23:09:17 +0200 |
| commit | 11a846e3d517c367112287f797065341e5e5c158 (patch) | |
| tree | c245a735787032e17ce0d6ded640cd61e9e6b144 /src | |
| parent | 276192f714d6816088791435c1b70dfa7122cdbd (diff) | |
| download | openttd-11a846e3d517c367112287f797065341e5e5c158.tar.xz | |
Change: Compensate for MIDI transmission time when skipping start of song
Diffstat (limited to 'src')
| -rw-r--r-- | src/music/dmusic.cpp | 3 | ||||
| -rw-r--r-- | src/music/win32_m.cpp | 9 |
2 files changed, 10 insertions, 2 deletions
diff --git a/src/music/dmusic.cpp b/src/music/dmusic.cpp index 3b6ae3454..3f5ca2255 100644 --- a/src/music/dmusic.cpp +++ b/src/music/dmusic.cpp @@ -693,6 +693,9 @@ static void MidiThreadProc(void *) current_segment.start_block = bl; break; } else { + /* Skip the transmission delay compensation performed in the Win32 MIDI driver. + * The DMusic driver will most likely be used with the MS softsynth, which is not subject to transmission delays. + */ DEBUG(driver, 2, "DMusic: timer: start from block %d (ticktime %d, realtime %.3f, bytes %d)", (int)bl, (int)block.ticktime, ((int)block.realtime) / 1000.0, (int)preload_bytes); playback_start_time -= block.realtime * MIDITIME_TO_REFTIME; break; diff --git a/src/music/win32_m.cpp b/src/music/win32_m.cpp index 93991d88b..3c059ebed 100644 --- a/src/music/win32_m.cpp +++ b/src/music/win32_m.cpp @@ -184,7 +184,7 @@ void CALLBACK TimerCallback(UINT uTimerID, UINT, DWORD_PTR dwUser, DWORD_PTR, DW /* find first block after start time and pretend playback started earlier * this is to allow all blocks prior to the actual start to still affect playback, * as they may contain important controller and program changes */ - size_t preload_bytes = 0; + uint preload_bytes = 0; for (size_t bl = 0; bl < _midi.current_file.blocks.size(); bl++) { MidiFile::DataBlock &block = _midi.current_file.blocks[bl]; preload_bytes += block.data.Length(); @@ -194,8 +194,13 @@ void CALLBACK TimerCallback(UINT uTimerID, UINT, DWORD_PTR dwUser, DWORD_PTR, DW _midi.current_segment.start_block = bl; break; } else { + /* Calculate offset start time for playback. + * The preload_bytes are used to compensate for delay in transmission over traditional serial MIDI interfaces, + * which have a bitrate of 31,250 bits/sec, and transmit 1+8+1 start/data/stop bits per byte. + * The delay compensation is needed to avoid time-compression of following messages. + */ DEBUG(driver, 2, "Win32-MIDI: timer: start from block %d (ticktime %d, realtime %.3f, bytes %d)", (int)bl, (int)block.ticktime, ((int)block.realtime) / 1000.0, (int)preload_bytes); - _midi.playback_start_time -= block.realtime / 1000; + _midi.playback_start_time -= block.realtime / 1000 - preload_bytes * 1000 / 3125; break; } } |