cpp/openttd-patchpack/source Changeset - r22910:67b1add3dd42

Changeset - r22910:67b1add3dd42

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Niels Martin Hansen - 6 years ago 2018-06-06 16:20:22
nielsm@indvikleren.dk

Change: Compensate for MIDI transmission time when skipping start of song

2 files changed with 10 insertions and 2 deletions:

src/music/dmusic.cpp

src/music/win32_m.cpp

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src/music/dmusic.cpp

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@@ @@ -690,12 +690,15 @@ static void MidiThreadProc(void *) @@
 					if (block.ticktime >= current_segment.start) {
 						if (current_segment.loop) {
 							DEBUG(driver, 2, "DMusic: timer: loop from block %d (ticktime %d, realtime %.3f, bytes %d)", (int)bl, (int)block.ticktime, ((int)block.realtime) / 1000.0, (int)preload_bytes);
 							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;
+						}
+					}
+				}

src/music/win32_m.cpp

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@@ @@ -181,24 +181,29 @@ void CALLBACK TimerCallback(UINT uTimerI @@
 	/* skip beginning of file? */
 	if (_midi.current_segment.start > 0 && _midi.current_block == 0 && _midi.current_segment.start_block == 0) {
 		/* 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();
 			if (block.ticktime >= _midi.current_segment.start) {
 				if (_midi.current_segment.loop) {
 					DEBUG(driver, 2, "Win32-MIDI: timer: loop from block %d (ticktime %d, realtime %.3f, bytes %d)", (int)bl, (int)block.ticktime, ((int)block.realtime)/1000.0, (int)preload_bytes);
 					_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;
+				}
+			}
+		}
+	}

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