Output replayed recordings to MIDI channel 1

The live output goes to channel 0. This prevents the two from messing
with each other (cancelling each others' notes).

Simply hard-coding channel 1 is a bad idea long-term, though. We
actually could have input from more than one channel (if we pump a midi
file into the program with "aplaymidi", for example). I suppose we want
to map the entire range of channels based on the input source in order
to prevent input sources from affecting one another. Then generated
playback could be considered a separate input source.

All of this will have to be done in order to deal with simultaneous
looping of multiple tracks, anyway.

2 files changed, 11 insertions, 1 deletions

diff --git a/Midi.hs b/Midi.hs
index cc14eb6..eac587c 100644
--- a/Midi.hs
+++ b/Midi.hs
@@ -91,6 +91,16 @@ convertEvents = mapMaybe (maybesnd . fmap conv)
       cpv f c p v = f (fi $ Event.unChannel c) (fi $ Event.unPitch p) (fi $ Event.unVelocity v)
       fi = fromIntegral
 
+setChannel :: Codec.Midi.Channel -> Codec.Midi.Message -> Codec.Midi.Message
+setChannel c (NoteOff _ k v) = (NoteOff c k v)
+setChannel c (NoteOn  _ k v) = (NoteOn  c k v)
+setChannel c (ProgramChange _ p) = (ProgramChange c p)
+setChannel c (ControlChange _ n v) = (ControlChange c n v)
+setChannel c (KeyPressure _ k p) = (KeyPressure c k p)
+setChannel c (ChannelPressure _ p) = (ChannelPressure c p)
+setChannel c (PitchWheel _ p) = (PitchWheel c p)
+setChannel _ x = x
+
 unConvertEvents :: [(TimeSpec, Codec.Midi.Message)] -> [(TimeSpec, Event.Data)]
 unConvertEvents = mapMaybe (maybesnd . fmap conv)
     where
diff --git a/midi-dump.hs b/midi-dump.hs
index 4c74792..534671f 100644
--- a/midi-dump.hs
+++ b/midi-dump.hs
@@ -215,7 +215,7 @@ playRecording = playEvents . playableEvents
 playEvents :: [RecordedEvent] -> RWST LoopEnv () LoopState IO ()
 playEvents evts@(_:_) =
   mapM_ (uncurry delayNoteEv) (zip (subtract (head delays) <$> delays) events)
-  where (delays, events) = unzip $ reverse $ unConvertEvents evts
+  where (delays, events) = unzip $ reverse $ unConvertEvents $ (fmap.fmap) (setChannel 1) evts
 playEvents  _ = return ()
 
 getMidiSender :: MidiController MidiHook