MIDI implementation current state and usecases

This wiki page was created to list the complete midi behaviour of H2 and address the questions found in https://github.com/hydrogen-music/hydrogen/issues/63

Note that the MIDI-related feature-requests/bugs/... can be listed with the MIDI related label.

Table of content

Testing the current implementation :

Test Setups

Test Setup A - 'dot-note' on Kick
Test Setup B - 'bar-note' on the Kick
Test Setup C - 'dot-note' on empty instrument
Test Setup D - 'bar-note' on empty instrument
Test Setup E - 'auto-stop-note' test

Test Cases

Test 1 - 'stop'
Test 2 - 'play'
Test 3 - 'play/stop'
Test 4 - place 'dot-note'
Test 5 - F12
Test 6 - 'auto stop note'

How it should work :

Use cases - how it should work

Testing current implementation

Notes

sequencer notation :
- 'dot-note' = the classic drum note (black dot)
- 'bar-note' = note with well defined duration (black bar)
using jack audio server (jackdmp 1.9.11)
using 'jack_midi_dump -r' to monitor midi output
- example output : +6144 : 90 0c 65 note on (channel 0): pitch 12, velocity 101
  - col1 (+6144) : relative time since previous midi messge
  - col2 (90 0c 65) : midi hex data
  - col3 (note on ... ) : human readable midi message

Test Setups

Test setup A :

default drumkit
1 dot-note on the kick on beat '1'
set midi channel for Kick instrument to 1
instrument 'midi note' = 36 (=default value)
1 pattern in the song, H2 in 'song mode', 'loop song' = off
lower tempo to 80

Test setup B :

same as setup A, but with these modifications :
pattern editor resolution : 32
1 'bar-note' on the Kick on beat '1', duration : 1/32th

this is the shortest 'bar-note' length possible and this is shorter that the duration of the Kick sample

Test setup C :

same as setup A, but with these modifications :
delete all samples (=all layers) of the Kick instruments making it a 'empty' instrument

Test setup D :

same as setup C, but with these modifications :
replace the 'dot-note' with a 'bar-note' with a duration if 1/32th note

Test setup E :

create a song with 1 pattern (song mode, not looped)
use a long sample (crash works fine)
place a dot on beat 1, and a second dot on beat 2

it is important that 'dot 2' is placed right after dot 1 so dot 2 can 'choke' the first dot
using 'piano roll editor' you can change the pitch of the second dot. This makes it easier to hear the difference between the 2 notes.
Also make the pitch of dot1 higher than dot 2. This ensures that the second note is longer than the first

Testcases

Each testcase consists of

a simple command
the midi output generated by H2
some remarks/observations

Test 1 : hit 'stop'

MIDI output Setup A, B, C, D

+11264: 80 24 00 note off (channel 0): pitch 36, velocity 0

Remarks:

Configured MIDI channel in H2 is '1' but here we see '0' > Seems that jack_midi_dump uses 0-based midi channels
GMIDImonitor reports '1' so this seems to confirm the above remark

Test 2 : hit 'play'

(pattern only plays 1 time since loop mode is off)

MIDI output Setup A

1)      0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2)     +1: 90 0c 65 note on  (channel  0): pitch  12, velocity 101
3) +19455: 80 0c 00 note off (channel  0): pitch  12, velocity   0
4) +64512: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks Setup A:

message 1 and 2 are simultaneous when hitting 'play'
message 3 is sent at the end of the sample
message 4 is sent when the song ends

MIDI output Setup B

1)       0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2)      +1: 90 0c 65 note on  (channel  0): pitch  12, velocity 101
3)   +5119: 80 0c 00 note off (channel  0): pitch  12, velocity   0
4) +121856: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks Setup B:

message 1 and 2 are simultaneous when hitting 'play'
message 3 is sent at the end of the 'bar-note'
message 4 is sent when the song ends

MIDI output Setup C & D

1)       0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2) +126976: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks Setup C & D:

message 1 is generated when hitting 'play'
message 2 is sent when the song ends

Possible issues for all Setups:

Why is message 1 sent out? Maybe it is a 'clean up' to make sure the note is not playing any more before starting it (dont think this is a problem)
Only the last message uses the correct pitch (=key 36), all other messages use an incorrect value of 12 (?)

Test 3 : play/pauze

hit play, wait for sample to play completely, hit pause and finally hit play and let the song finish

MIDI output Setup A & B

1)      0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2)     +1: 90 0c 65 note on  (channel  0): pitch  12, velocity 101
3) +19455: 80 0c 00 note off (channel  0): pitch  12, velocity   0  (for setup A)
3)  +5119: 80 0c 00 note off (channel  0): pitch  12, velocity   0  (for Setup B)
4) +55296: 80 24 00 note off (channel  0): pitch  36, velocity   0
5) +14848: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks setup A & B:

message 1 and 2 are simultaneous when hitting 'play'
message 3 is sent at the end of the sample (or bar-note for Setup B)
message 4 is sent when you hit 'pause'
message 5 is sent when the song ends

MIDI output Setup C & D

1)       0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2)  +53248: 80 24 00 note off (channel  0): pitch  36, velocity   0
3) +224256: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks setup C & D:

message 1 is generated when hitting 'play'
message 2 is sent when you hit 'pause'
message 3 is sent when the song ends

Possible issues:

incorrect note 36<>12 for first 3 messages
the messages that are triggered by the transport buttons use the correct note 36

Test 4 : place 'dot-note'

Place a 'dot-note' on the Kick by clicking on the Kick sequence line in the pattern editor

MIDI output setup A & B

1)      0: 80 0c 00 note off (channel  0): pitch  12, velocity   0
2)     +1: 90 0c 65 note on  (channel  0): pitch  12, velocity 101
3) +19455: 80 0c 00 note off (channel  0): pitch  12, velocity   0

Remarks for setup A & B:

message 1 and 2 are sent out simultaneously when you place the 'dot-note'
message 3 is sent out when the sample stops playing
the same midi output is generated when you play the note using the PC keyboard (key Z for Kick)

MIDI output setup C & D

  : 80 0c 00 note off (channel  0): pitch  12, velocity   0

Possible issues for all setups:

wrong note (should be 36)

Test 5 : hit F12

Hitting F12 pauses playback and should mute all playing sounds

MIDI output (Setup A-D)

1)     0: 80 24 00 note off (channel  0): pitch  36, velocity   0

Remarks: none

Possible issues: none

Test 6 : test 'auto stop note' function

Hit play. the song (containing only 1 pattern) plays and stops at the end of the song.

MIDI output (Setup E)

1)       : 80 19 00 note off (channel  0): pitch  25, velocity   0
2)     +1: 90 19 65 note on  (channel  0): pitch  25, velocity 101
3)  +5375: 80 18 00 note off (channel  0): pitch  24, velocity   0
4)     +1: 90 18 65 note on  (channel  0): pitch  24, velocity 101
5) +93695: 80 19 00 note off (channel  0): pitch  25, velocity   0
6) +11520: 80 18 00 note off (channel  0): pitch  24, velocity   0
7) +61952: 80 31 00 note off (channel  0): pitch  49, velocity   0