Messages¶
A Mido message is a Python object with methods and attributes. The attributes will vary depending on message type.
To create a new message:
>>> mido.Message('note_on')
Message('note_on', channel=0, note=0, velocity=64, time=0)
You can pass attributes as keyword arguments:
>>> mido.Message('note_on', note=100, velocity=3, time=6.2)
Message('note_on', channel=0, note=100, velocity=3, time=6.2)
All attributes will default to 0. The exceptions are velocity
,
which defaults to 64 (middle velocity) and data
which defaults to
()
.
You can set and get attributes as you would expect:
>>> msg = mido.Message('note_on')
>>> msg.note
0
The type
attribute can be used to determine message type:
>>> msg.type
'note_on'
Attributes are also settable but it’s always better to use
msg.copy()
:
>>> msg.copy(note=99, time=100.0)
Message('note_on', channel=0, note=99, velocity=64, time=100.0)
Note
Mido always makes a copy of messages instead of modifying them so if you do the same you have immutable messages in practice. (Third party libraries may not follow the same rule.)
Note
Frozen Messages are a variant of messages that are hashable and can be used as dictionary keys. They are also safe from tampering by third party libraries. You can freely convert between the two and use frozen messages wherever normal messages are allowed.
Mido supports all message types defined by the MIDI standard. For a full list of messages and their attributes, see Message Types.
Control Changes¶
if msg.is_cc():
print('Control change message received')
if msg.is_cc(7):
print('Volume changed to', msg.value)
Converting To Bytes¶
You can convert a message to MIDI bytes with one of these methods:
>>> msg = mido.Message('note_on')
>>> msg
Message('note_on', channel=0, note=0, velocity=64, time=0)
>>> msg.bytes()
[144, 0, 64]
>>> msg.bin()
bytearray(b'\x90\x00@')
>>> msg.hex()
'90 00 40'
Converting From Bytes¶
You can turn bytes back into messages with the /parser.
You can also create a message from bytes using class methods (new in 1.2):
msg1 = mido.Message.from_bytes([0x90, 0x40, 0x60])
msg2 = mido.Message.from_hex('90, 40 60')
The bytes must contain exactly one complete message. If not
ValueError
is raised.
The Time Attribute¶
Each message has a time
attribute, which can be set to any value
of type int
or float
(and in Python 2 also long
).
Some parts of Mido use the attribute for special purposes. In MIDI file tracks, it is used as delta time (in ticks), and it must be a non-negative integer.
In other parts of Mido, this value is ignored.
Note
Before 1.1.18 the time
attribute was not included in
comparisons. If you want the old behavior the easies way is
msg1.bytes()
== msg2.bytes()
.
To sort messages on time you can do:
messages.sort(key=lambda message: message.time)
or:
import operator
messages.sort(key=operator.attrgetter('time'))
System Exclusive Messages¶
System Exclusive (SysEx) messages are used to send device specific
data. The data
attribute is a tuple of data bytes which serves as
the payload of the message:
>>> msg = Message('sysex', data=[1, 2, 3])
>>> msg
Message('sysex', data=(1, 2, 3), time=0)
>>> msg.hex()
'F0 01 02 03 F7'
You can also extend the existing data:
>>> msg = Message('sysex', data=[1, 2, 3])
>>> msg.data += [4, 5]
>>> msg.data += [6, 7, 8]
>>> msg
Message('sysex', data=(1, 2, 3, 4, 5, 6, 7, 8), time=0)
Any sequence of integers is allowed, and type and range checking is applied to each data byte. These are all valid:
(65, 66, 67)
[65, 66, 67]
(i + 65 for i in range(3))
(ord(c) for c in 'ABC')
bytearray(b'ABC')
b'ABC' # Python 3 only.
For example:
>>> msg = Message('sysex', data=bytearray(b'ABC'))
>>> msg.data += bytearray(b'DEF')
>>> msg
Message('sysex', data=(65, 66, 67, 68, 69, 70), time=0)