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Overhaul documentation about MIDI support

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Micky
2023-12-31 18:47:18 +01:00
parent 17e7f85c06
commit 8723d116c4
2 changed files with 59 additions and 48 deletions
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64
doc/classes/InputEventMIDI.xml
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@ -1,12 +1,12 @@
<?xml version="1.0" encoding="UTF-8" ?>
<class name="InputEventMIDI" inherits="InputEvent" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
<brief_description>
Represents an input event from a MIDI device, such as a piano.
Represents a MIDI message from a MIDI device, such as a musical keyboard.
</brief_description>
<description>
InputEventMIDI allows receiving input events from MIDI (Musical Instrument Digital Interface) devices such as a piano.
MIDI signals can be sent over a 5-pin MIDI connector or over USB, if your device supports both be sure to check the settings in the device to see which output it's using.
To receive input events from MIDI devices, you need to call [method OS.open_midi_inputs]. You can check which devices are detected using [method OS.get_connected_midi_inputs].
InputEventMIDI stores information about messages from [url=https://en.wikipedia.org/wiki/MIDI]MIDI[/url] (Musical Instrument Digital Interface) devices. These may include musical keyboards, synthesizers, and drum machines.
MIDI messages can be received over a 5-pin MIDI connector or over USB. If your device supports both be sure to check the settings in the device to see which output it is using.
By default, Godot does not detect MIDI devices. You need to call [method OS.open_midi_inputs], first. You can check which devices are detected with [method OS.get_connected_midi_inputs], and close the connection with [method OS.close_midi_inputs].
[codeblocks]
[gdscript]
func _ready():
@ -17,16 +17,16 @@
if input_event is InputEventMIDI:
_print_midi_info(input_event)
func _print_midi_info(midi_event: InputEventMIDI):
func _print_midi_info(midi_event):
print(midi_event)
print("Channel " + str(midi_event.channel))
print("Message " + str(midi_event.message))
print("Pitch " + str(midi_event.pitch))
print("Velocity " + str(midi_event.velocity))
print("Instrument " + str(midi_event.instrument))
print("Pressure " + str(midi_event.pressure))
print("Controller number: " + str(midi_event.controller_number))
print("Controller value: " + str(midi_event.controller_value))
print("Channel ", midi_event.channel)
print("Message ", midi_event.message)
print("Pitch ", midi_event.pitch)
print("Velocity ", midi_event.velocity)
print("Instrument ", midi_event.instrument)
print("Pressure ", midi_event.pressure)
print("Controller number: ", midi_event.controller_number)
print("Controller value: ", midi_event.controller_value)
[/gdscript]
[csharp]
public override void _Ready()
@ -35,9 +35,9 @@
GD.Print(OS.GetConnectedMidiInputs());
}
public override void _Input(InputEvent @event)
public override void _Input(InputEvent inputEvent)
{
if (@event is InputEventMIDI midiEvent)
if (inputEvent is InputEventMIDI midiEvent)
{
PrintMIDIInfo(midiEvent);
}
@ -57,7 +57,7 @@
}
[/csharp]
[/codeblocks]
Note that Godot does not currently support MIDI output, so there is no way to emit MIDI signals from Godot. Only MIDI input works.
[b]Note:[/b] Godot does not support MIDI output, so there is no way to emit MIDI messages from Godot. Only MIDI input is supported.
</description>
<tutorials>
<link title="MIDI Message Status Byte List">https://www.midi.org/specifications-old/item/table-2-expanded-messages-list-status-bytes</link>
@ -66,33 +66,39 @@
</tutorials>
<members>
<member name="channel" type="int" setter="set_channel" getter="get_channel" default="0">
The MIDI channel of this input event. There are 16 channels, so this value ranges from 0 to 15. MIDI channel 9 is reserved for the use with percussion instruments, the rest of the channels are for non-percussion instruments.
The MIDI channel of this message, ranging from [code]0[/code] to [code]15[/code]. MIDI channel [code]9[/code] is reserved for percussion instruments.
</member>
<member name="controller_number" type="int" setter="set_controller_number" getter="get_controller_number" default="0">
If the message is [constant MIDI_MESSAGE_CONTROL_CHANGE], this indicates the controller number, otherwise this is zero. Controllers include devices such as pedals and levers.
The unique number of the controller, if [member message] is [constant MIDI_MESSAGE_CONTROL_CHANGE], otherwise this is [code]0[/code]. This value can be used to identify sliders for volume, balance, and panning, as well as switches and pedals on the MIDI device. See the [url=https://en.wikipedia.org/wiki/General_MIDI#Controller_events]General MIDI specification[/url] for a small list.
</member>
<member name="controller_value" type="int" setter="set_controller_value" getter="get_controller_value" default="0">
If the message is [constant MIDI_MESSAGE_CONTROL_CHANGE], this indicates the controller value, otherwise this is zero. Controllers include devices such as pedals and levers.
The value applied to the controller. If [member message] is [constant MIDI_MESSAGE_CONTROL_CHANGE], this value ranges from [code]0[/code] to [code]127[/code], otherwise it is [code]0[/code]. See also [member controller_value].
</member>
<member name="instrument" type="int" setter="set_instrument" getter="get_instrument" default="0">
The instrument of this input event. This value ranges from 0 to 127. Refer to the instrument list for [url=https://en.wikipedia.org/wiki/General_MIDI#Program_change_events]General MIDI[/url] to see a list of instruments, except that this value is 0-index, so subtract one from every number on that chart. A standard piano will have an instrument number of 0.
The instrument (also called [i]program[/i] or [i]preset[/i]) used on this MIDI message. This value ranges from [code]0[/code] to [code]127[/code].
To see what each value means, refer to the [url=https://en.wikipedia.org/wiki/General_MIDI#Program_change_events]General MIDI's instrument list[/url]. Keep in mind that the list is off by 1 because it does not begin from 0. A value of [code]0[/code] corresponds to the acoustic grand piano.
</member>
<member name="message" type="int" setter="set_message" getter="get_message" enum="MIDIMessage" default="0">
Returns a value indicating the type of message for this MIDI signal. This is a member of the [enum MIDIMessage] enum.
For MIDI messages between 0x80 and 0xEF, only the left half of the bits are returned as this value, as the other part is the channel (ex: 0x94 becomes 0x9). For MIDI messages from 0xF0 to 0xFF, the value is returned as-is.
Notes will return [constant MIDI_MESSAGE_NOTE_ON] when activated, but they might not always return [constant MIDI_MESSAGE_NOTE_OFF] when deactivated, therefore your code should treat the input as stopped if some period of time has passed.
Some MIDI devices may send [constant MIDI_MESSAGE_NOTE_ON] with zero velocity instead of [constant MIDI_MESSAGE_NOTE_OFF].
For more information, see the note in [member velocity] and the MIDI message status byte list chart linked above.
Represents the type of MIDI message (see the [enum MIDIMessage] enum).
For more information, see the [url=https://www.midi.org/specifications-old/item/table-2-expanded-messages-list-status-bytes]MIDI message status byte list chart[/url].
</member>
<member name="pitch" type="int" setter="set_pitch" getter="get_pitch" default="0">
The pitch index number of this MIDI signal. This value ranges from 0 to 127. On a piano, middle C is 60, and A440 is 69, see the "MIDI note" column of the piano key frequency chart on Wikipedia for more information.
The pitch index number of this MIDI message. This value ranges from [code]0[/code] to [code]127[/code].
On a piano, the [b]middle C[/b] is [code]60[/code], followed by a [b]C-sharp[/b] ([code]61[/code]), then a [b]D[/b] ([code]62[/code]), and so on. Each octave is split in offsets of 12. See the "MIDI note number" column of the [url=https://en.wikipedia.org/wiki/Piano_key_frequencies]piano key frequency chart[/url] a full list.
</member>
<member name="pressure" type="int" setter="set_pressure" getter="get_pressure" default="0">
The pressure of the MIDI signal. This value ranges from 0 to 127. For many devices, this value is always zero.
The strength of the key being pressed. This value ranges from [code]0[/code] to [code]127[/code].
[b]Note:[/b] For many devices, this value is always [code]0[/code]. Other devices such as musical keyboards may simulate pressure by changing the [member velocity], instead.
</member>
<member name="velocity" type="int" setter="set_velocity" getter="get_velocity" default="0">
The velocity of the MIDI signal. This value ranges from 0 to 127. For a piano, this corresponds to how quickly the key was pressed, and is rarely above about 110 in practice.
[b]Note:[/b] Some MIDI devices may send a [constant MIDI_MESSAGE_NOTE_ON] message with zero velocity and expect this to be treated the same as a [constant MIDI_MESSAGE_NOTE_OFF] message, but device implementations vary so Godot reports event data exactly as received. Depending on the hardware and the needs of the game/app, this MIDI quirk can be handled robustly with a couple lines of script (check for [constant MIDI_MESSAGE_NOTE_ON] with velocity zero).
The velocity of the MIDI message. This value ranges from [code]0[/code] to [code]127[/code]. For a musical keyboard, this corresponds to how quickly the key was pressed, and is rarely above [code]110[/code] in practice.
[b]Note:[/b] Some MIDI devices may send a [constant MIDI_MESSAGE_NOTE_ON] message with [code]0[/code] velocity and expect it to be treated the same as a [constant MIDI_MESSAGE_NOTE_OFF] message. If necessary, this can be handled with a few lines of code:
[codeblock]
func _input(event):
if event is InputEventMIDI:
if event.message == MIDI_MESSAGE_NOTE_ON and event.velocity &gt; 0:
print("Note pressed!")
[/codeblock]
</member>
</members>
</class>