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Getting Started with MIDI
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Topic starter
I already parsed MIDI files 10 years ago - or created them.
This is a MIDI file created with MuseScore - I want to parse it, but:
00000000 4d 54 68 64 00 00 00 06 00 01 00 01 01 e0 4d 54 MThd..........MT
00000010 72 6b 00 00 06 d5 00 ff 03 05 50 69 61 6e 6f 00 rk........Piano.
00000020 ff 58 04 04 02 18 08 00 ff 59 02 00 00 00 ff 51 .X.......Y.....Q
00000030 03 07 a1 20 00 b0 79 00 00 64 00 00 65 00 00 06 ... ..y..d..e...
00000040 0c 00 64 7f 00 65 7f 00 c0 00 00 b0 07 64 00 0a ..d.e......d..
00000050 40 00 5b 00 00 5d 00 00 ff 21 01 00 00 90 24 50 @.[..]...!....$P
00000060 00 ff 05 02 43 32 00 ff 05 01 43 83 47 90 24 00 ....C2....C.G.$.
00000070 19 26 50 00 ff 05 02 44 32 00 ff 05 01 44 83 47 .&P....D2....D.G
00000080 90 26 00 19 28 50 00 ff 05 02 45 32 00 ff 05 01 .&..(P....E2....
00000090 45 83 47 90 28 00 19 29 50 00 ff 05 02 46 32 00 E.G.(..)P....F2.
...
b0 79 00 is a controller event - right?
after a delay of 00 ticks
64
follows, but AFAIK all event type IDs start from 0x80 (to 0xFF).
So what kind of event ID is 0x64? Or what I did not parse properly?
(Later such pattern occurs again)
At my parsing ouput:
... Delay: 0 ticks from 22/0x16 with 1/0x01 bytes: 0x00 'MetaEvent' from 23/0x17 with 8/0x08 bytes: 0xff 0x03 0x05 0x50 0x69 0x61 0x6e 0x6f Delay: 0 ticks from 31/0x1f with 1/0x01 bytes: 0x00 'MetaEvent' from 32/0x20 with 7/0x07 bytes: 0xff 0x58 0x04 0x04 0x02 0x18 0x08 Delay: 0 ticks from 39/0x27 with 1/0x01 bytes: 0x00 'MetaEvent' from 40/0x28 with 5/0x05 bytes: 0xff 0x59 0x02 0x00 0x00 Delay: 0 ticks from 45/0x2d with 1/0x01 bytes: 0x00 'MetaEvent' from 46/0x2e with 6/0x06 bytes: 0xff 0x51 0x03 0x07 0xa1 0x20 Delay: 0 ticks from 52/0x34 with 1/0x01 bytes: 0x00 MidiParser.events.ControllerEvent from 53/0x35 with 3/0x03 bytes: 0xb0 0x79 0x00 Delay: 0 ticks from 56/0x38 with 1/0x01 bytes: 0x00 MidiParser.events.IntermediateImplementationEvent from 57/0x39 with 2/0x02 bytes: 0x64 0x00
What event is the the last byte 0x64 (and 0x00) in the last line?
Any documentation, link for its explanation?
Posted : 06/03/2025 3:55 pm
This is Running Status. When you see a data byte where you'd expect a status byte, then you have to use the last status byte (here, 0xB0).
Posted : 07/03/2025 12:35 am
In a MIDI file, if a channel-based MIDI message (status bytes hex 80 to EF) has the same status byte as the previous message, you are allowed to omit the status byte to save space.
In your example:
B0 79 00 is Control Change Channel 1, Reset All Controllers, Value 0 not used 64 00 is " " " ", Registered Parameter Number LSB, Value 0 ─┐ 65 00 is " " " ", Registered Parameter Number MSB, Value 0 │ 06 0C is " " " ", Data Entry MSB, Value 12 ─┴─ is Pitch Bend Range, 12 semitones
In the Standard MIDI Files 1.0 specification, this ability is mentioned on PDF page 8, printed page 6:
<event> = <MIDI event> | <sysex event> | <meta-event>
<MIDI event> is any MIDI channel message. Running status is used: status bytes of MIDI channel messages may be omitted if the preceding event is a MIDI channel message with the same status. The first event in each MTrk chunk must specify status. Delta-time is not considered an event itself: it is an integral part of the syntax for an MTrk event. Notice that running status occurs across delta-times.
Posted : 07/03/2025 1:55 am
Markus Weber reacted
Topic starter
Your answer and example is perfect, thanks a lot.
I read the cited part, but was unsure because I would have never titled the byte containing the nibble for the MIDI event type and the nibble for the channel as "running status" - perhaps "event type (and channel) byte" or "message initalization byte". When I googled the term, I did not find anything similar - this term seems to be solely used in the MIDI documentation - or then for states of operation of mechanical engines or similar stuff.
AFAIK is there no general description of a MIDI channel message's parts like the "status".
I would welcome if the documentation is clarified in that manner with an example like yours.
If found also this link, where the "running status" is explained IMHO with enough details to build a successful parser.
Posted : 07/03/2025 3:40 pm
