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MidiSource: Fix some channels being mute after looping

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This commit is contained in:
Jonas Kulla 2015-01-21 16:51:00 +01:00
parent 64a3ac3769
commit e339964076
2 changed files with 71 additions and 9 deletions
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74
src/midisource.cpp
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@ -55,7 +55,13 @@
#define TICK_FRAMES 32
#define BUF_TICKS (STREAM_BUF_SIZE / TICK_FRAMES)
#define DEFAULT_BPM 120
#define LOOP_MARKER 111
#define MAX_CHANNELS 16
#define CC_CTRL_VOLUME 7
#define CC_CTRL_EXPRESSION 11
#define CC_CTRL_LOOP 111
#define CC_VAL_DEFAULT 127
enum MidiEventType
{
@ -522,6 +528,59 @@ struct Track
}
};
/* Some songs use CC events for effects like fade-out,
* slowly decreasing a channel's volume to 0. The problem is that
* for looped songs, events are continuously fed into the synth
* without restoring those controls back to their default value.
* We can't reset them at the very beginning of tracks because it
* might cause audible interactions with notes which are still decaying
* past the end of the song. Therefore, we insert a fake CC event right
* after the first NoteOn event for each channel which resets the
* control to its default state while avoiding audible glitches.
* If there is already a CC event for this control before the first
* NoteOn event, we don't clobber it by not inserting our fake event. */
template<uint8_t ctrl>
struct CCResetter
{
bool chanHandled[MAX_CHANNELS];
CCResetter()
{
memset(&chanHandled, 0, sizeof(chanHandled));
}
void handleEvent(const MidiEvent &e, Track &track)
{
if (e.type != NoteOn && e.type != CC)
return;
uint8_t chan = e.e.chan.chan;
if (chanHandled[chan])
return;
if (e.type == CC && e.e.cc.ctrl == ctrl)
{
/* Don't clobber the existing CC value */
chanHandled[chan] = true;
return;
}
else if (e.type == NoteOn)
{
chanHandled[chan] = true;
MidiEvent re;
re.delta = 0;
re.type = CC;
re.e.cc.chan = chan;
re.e.cc.ctrl = ctrl;
re.e.cc.val = CC_VAL_DEFAULT;
track.appendEvent(re);
}
}
};
struct MidiSource : ALDataSource, MidiReadHandler
{
const uint16_t freq;
@ -530,6 +589,8 @@ struct MidiSource : ALDataSource, MidiReadHandler
int16_t synthBuf[BUF_TICKS*TICK_FRAMES*2];
std::vector<Track> tracks;
CCResetter<CC_CTRL_VOLUME> volReset;
CCResetter<CC_CTRL_EXPRESSION> expReset;
/* Index of longest track */
uint8_t longestI;
@ -631,7 +692,7 @@ struct MidiSource : ALDataSource, MidiReadHandler
playbackSpeed = TICK_FRAMES / (deltaLength * freq);
}
void activateEvent(MidiEvent &e)
void activateEvent(const MidiEvent &e)
{
int16_t key = e.e.note.key;
@ -705,9 +766,14 @@ struct MidiSource : ALDataSource, MidiReadHandler
void onMidiEvent(const MidiEvent &e, uint32_t absDelta)
{
assert(curTrack >= 0 && curTrack < (int16_t) tracks.size());
tracks[curTrack].appendEvent(e);
if (e.type == CC && e.e.cc.ctrl == LOOP_MARKER)
Track &track = tracks[curTrack];
track.appendEvent(e);
volReset.handleEvent(e, track);
expReset.handleEvent(e, track);
if (e.type == CC && e.e.cc.ctrl == CC_CTRL_LOOP)
loopDelta = absDelta;
}