MIDI and USB Keyboard!

Sascha Lefevre

Controls (a Form, ComboBox, TextBox..) can only be accessed by the UI-thread. That's the thread that created them and the thread that executes all your code unless you either explicitly create additional threads or use some kind of event/callback mechanism - the latter you apparently do here:

midiInOpen(hMidiIn, DeviceID, AddressOf MidiInProc, 0, CALLBACK_FUNCTION)

So that midi-library you're using seems to call your function MidiInProc(..) on a different thread than your UI-thread and then tries to access cboduration.Text which is one of your controls which may only be accessed by your UI thread. That's the problem. The easiest solution for you here is this: Read the value of cboduration.Text into a class variable (let's call it duration) the moment that it is changed by the user. Also initialize that variable with the same value as the control. Then replace this:

m.NoteDuration = CInt(cboduration.Text)

..by this:

m.NoteDuration = duration

Now the UI thread does the reading from the control and the thread that executes MidiInProc doesn't "touch" any controls any more.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

"The easiest solution for you here is this: Read the value of cboduration.Text into a class variable (let's call it duration) the moment that it is changed by the user. Also initialize that variable with the same value as the control." May you show me the code for this...??? Thank you!

Lost User

Well? .. i realy would like to have this working?! Thanks, Duarte

Sascha Lefevre

Alienoiz wrote:

Well? .. i realy would like to have this working?!

Please note that we're all volunteers here, answering questions in our free time, not getting paid for it. And there are also other things I enjoy doing in my free time. You're already doing what would be required for NoteDuration for other settings, like CurrentInstrument. You just need to do the same for the duration.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

sorry..i am too lame for that..and ..i am not understanding... and btw..i respect you all..i am not making funny of you or anything like that...i ask..if you want to reply the better, if not, i must live with it without complaints...i aprecciate your efforts and etc... I am not a "sucking" guy.. Thanks, Duarte

Sascha Lefevre

Alienoiz wrote:

sorry..i am too lame for that..and ..i am not understanding... and btw..i respect you all..i am not making funny of you or anything like that...i ask..if you want to reply the better, if not, i must live with it without complaints...i aprecciate your efforts and etc... I am not a "sucking" guy..

Let me clarify. Yes, of course I want to be respected. But not by being sucked up to. Eew. No - my idea here of helping people is to teach. So they learn and can do it themselves next time. So the way I want to be respected is by people taking the advice and at least making an effort to implement it by themselves. One more attempt:

Function MidiInProc(ByVal hMidiIn As Integer, ByVal wMsg As UInteger, ByVal dwInstance As Integer, ByVal dwParam1 As Integer, ByVal dwParam2 As Integer) As Integer
    Dim DataByte1 = (dwParam1) >> 8
    m.PlayMIDINote(DataByte1, 127)
    m.NoteDuration = CInt(cboduration.Text)
    m.Pan = 50
End Function

The underlined line is the problem. You can't access cboduration inside that function because it's being executed by a different thread that originates from that MIDI-component. But only the UI-thread may access controls. You already modify other settings (than NoteDuration) on the UI-thread. Example:

Private Sub cboInstruments\_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboInstruments.SelectedIndexChanged
    m.CurrentInstrument = cboInstruments.Text
End Sub

You need to do the same for m.NoteDuration.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

well..thanks..but i still do not understand.. i am not a coder..i just make these small gadgets to keep my head busy... I know the very basics of VB but normaly i interpret snippets and get them together to create my code on more advanced stuff... So i may be able to do what you say, but i am not understanding how..if i see the code, i understand it, but creating it is not my strongest point! I hope i am making myself clear!

Sascha Lefevre

Alienoiz wrote:

i am not a coder..i just make these small gadgets to keep my head busy...

Why don't you start to learn it properly? Open the form designer. Right-click the CombBox for the note-duration and select Properties. In the properties pane click on the events-icon (small and easy to miss). Search for the SelectedIndexChanged-event in the list and make a double-click into the empty column to the right of it. Visual Studio switches to the source code and you will see a stub for the event-handler-function where you will only have to insert that one line from my previous message. Remove that line I underlined in the other function in my previous message. That should be it.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

ah..OK ..i was complicating cause i wasnt seeing the code..it works but my app seems to Break when i press several keys of the controller! Thanks anyway!

Lost User

may i ask for your attention once again? my code has changed....i am now able to do everything i want from it...but i am just having a small problem... When i press the midi key of my controller it plays the note and when i unpress it it also plays the same note! I have tried the .StopMIDINote() function but i do not know where to insert it?!!! If i was using a button i would know..mousedown play..mouseup stop..but i am using my MIDI hardware keyboard! Below i show the code....if you have some advice i would appreciate it?!!?!? Thanks You!

Public Class Form1
Dim m As New clsMIDI
Dim hMidiIn As Integer

Private Sub Form1\_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    FillInstrumentCombo()

    If midiInGetNumDevs() = 0 Then
        MsgBox("No MIDI devices connected")
    End If

    Dim InCaps As New MIDIINCAPS
    Dim DevCnt As Integer

    For DevCnt = 0 To (midiInGetNumDevs - 1)
        midiInGetDevCaps(DevCnt, InCaps, Len(InCaps))
        ComboBox1.Items.Add(InCaps.szPname)
    Next DevCnt


End Sub

Private Sub Form1\_Closed(sender As Object, e As EventArgs) Handles Me.Closed
    midiInStop(hMidiIn)
    midiInReset(hMidiIn)
    midiInClose(hMidiIn)
End Sub
Public Declare Function midiInOpen Lib "winmm.dll" (ByRef hMidiIn As Integer, ByVal uDeviceID As Integer, ByVal dwCallback As MidiInCallback, ByVal dwInstance As Integer, ByVal dwFlags As Integer) As Integer
Public Delegate Function MidiInCallback(ByVal hMidiIn As Integer, ByVal wMsg As UInteger, ByVal dwInstance As Integer, ByVal dwParam1 As Integer, ByVal dwParam2 As Integer) As Integer
Public ptrCallback As New MidiInCallback(AddressOf MidiInProc)
Public Const CALLBACK\_FUNCTION As Integer = &H30000
Public Const MIDI\_IO\_STATUS = &H20

Public Delegate Sub DisplayDataDelegate(dwParam1)

Private Sub ComboBox1\_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
    Dim DeviceID As Integer = ComboBox1.SelectedIndex
    midiInOpen(hMidiIn, DeviceID, ptrCallback, 0, CALLBACK\_FUNCTION Or MIDI\_IO\_STATUS)
    midiInStart(hMidiIn)
    Dim duration = CInt(cboduration.Text)
    m.NoteDuration = duration
End Sub

Dim DataByte1 As Byte

Function MidiInProc(ByVal hMidiIn As Integer, ByVal wMsg As UInteger, ByVal dwInstance As Integer, ByVal dwParam1 As Integer, ByVal dwParam2 As Integer) As Integer

Lost User

may you help me or not?..i just wanna know so i can quit the gadget or not!! Thank you!

Sascha Lefevre

On the page you linked in another post (Visual Basic MIDI Piano[^]) there are these two subs which I assume are still somewhere in your code:

Private Sub Down(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Button1.MouseDown, Button2.MouseDown, Button3.MouseDown, Button4.MouseDown, Button5.MouseDown, Button6.MouseDown, Button7.MouseDown, Button8.MouseDown, Button9.MouseDown, Button10.MouseDown, Button11.MouseDown, Button12.MouseDown, Button13.MouseDown, Button14.MouseDown, Button15.MouseDown, Button16.MouseDown, Button17.MouseDown, Button18.MouseDown, Button19.MouseDown, Button20.MouseDown, Button21.MouseDown, Button22.MouseDown, Button23.MouseDown, Button24.MouseDown
    Jazz.MidiOut(&H90 + chan, Note(sender), 100)
End Sub

Private Sub Up(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Button1.MouseUp, Button2.MouseUp, Button3.MouseUp, Button4.MouseUp, Button5.MouseUp, Button6.MouseUp, Button7.MouseUp, Button8.MouseUp, Button9.MouseUp, Button10.MouseUp, Button11.MouseUp, Button12.MouseUp, Button13.MouseUp, Button14.MouseUp, Button15.MouseUp, Button16.MouseUp, Button17.MouseUp, Button18.MouseUp, Button19.MouseUp, Button20.MouseUp, Button21.MouseUp, Button22.MouseUp, Button23.MouseUp, Button24.MouseUp
    Jazz.MidiOut(&H80 + chan, Note(sender), 0)
End Sub

Looks like it's supposed to start playing a note on KeyDown and stop playing it on KeyUp, without a predetermined duration, which you seem to have added. So I'm guessing all you need to do is to either remove the "Up"-sub and the event-wiring for it or comment out the single line it it. If it doesn't work then I have no idea.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

hi..i am not using the jazzmidi control anymore! Now i am using a module called clsMIDI! You can check it in the concorrence : ) (sorry) https://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=8305&lngWId=10 Thanks!

Lost User

I think the solution is somewhere in these lines of code:

Dim DataByte1 = (dwParam1 And &HFF00) >> 8
m.PlayMIDINote(DataByte1, 127)

If i leave like that, when i press the key of my MIDI Controller the note plays and when i unpress it it plays again! But if i set it like this:

Dim DataByte1 = (dwParam1) >> 8
m.PlayMIDINote(DataByte1, 127)

It only plays when i unpress the key.... Well.... it is the opposite of what i need...i need it to play when i press and silent when i unpress!!

Lost User

Well...do you have any tip? Thanks you!

Sascha Lefevre

In the code you linked a note gets played by a mouse left click. You say you play notes by pressing keys but I don't see any of that in your code. Can you show the code that handles key presses?

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

The keys i say are the keys from my piano MIDI keyboard (hardware piano keyboard)!... Not from PC´s keyboard!!! This is all the code i have now....plus the clsMIDI module:

Imports System.Runtime.InteropServices

Public Class Form1
Dim m As New clsMIDI
Dim hMidiIn As Integer

Private Sub Form1\_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    FillInstrumentCombo()

    If midiInGetNumDevs() = 0 Then
        MsgBox("No MIDI devices connected!")
    End If

    Dim InCaps As New MIDIINCAPS
    Dim DevCnt As Integer

    For DevCnt = 0 To (midiInGetNumDevs - 1)
        midiInGetDevCaps(DevCnt, InCaps, Len(InCaps))
        ComboBox1.Items.Add(InCaps.szPname)
    Next DevCnt


End Sub

Declare Function midiInOpen Lib "winmm.dll" (ByRef lphMidiIn As Integer,
    ByVal uDeviceID As Integer,  ByVal dwCallback As MidiDelegate,
    ByVal dwInstance As Integer, ByVal dwFlags As Integer) As Integer
Public Delegate Sub MidiDelegate(ByVal MidiInHandle As Int32, ByVal wMsg As Int32, ByVal Instance As Int32, ByVal wParam As Int32, ByVal lParam As Int32)
Public ptrCallback As New MidiDelegate(AddressOf MidiInProc)

Public Delegate Sub DisplayDataDelegate(wParam)

Private Sub ComboBox1\_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
    midiInStop(hMidiIn)
    midiInReset(hMidiIn)
    midiInClose(hMidiIn)
    Dim DeviceID As Integer = ComboBox1.SelectedIndex
    midiInOpen(hMidiIn, DeviceID, ptrCallback, 0, CALLBACK\_FUNCTION Or MIDI\_IO\_STATUS)
    midiInStart(hMidiIn)
    Dim duration = CInt(cboduration.Text)
    m.NoteDuration = duration
End Sub



Function MidiInProc(ByVal MidiInHandle As Int32, ByVal wMsg As Int32, ByVal Instance As Int32, ByVal wParam As Int32, ByVal lParam As Int32) As Integer
    TextBox1.Invoke(New DisplayDataDelegate(AddressOf DisplayData), New Object() {wParam})
    Dim DataByte3 = (wParam And &HFF00) >> 8
    m.PlayMIDINote(DataByte3, 127)
End Function

Private Sub DisplayData(wParam)
    Dim StatusByte As Byte
    Dim DataByte1 As Byte
    Dim DataByte2 As Byte
    StatusByte = (wParam And &HFF)
    DataByte1 = (wParam And &HFF00) >> 8
    DataByte2 = (wParam And &HFF0000) >> 16
    TextBox1.AppendText(String.Format("{0:X2} {1:X2} {2:X2}{3}", StatusByte, DataByte1, D

Sascha Lefevre

Alienoiz wrote:

The keys i say are the keys from my piano MIDI keyboard (hardware piano keyboard)!... Not from PC´s keyboard!!!

Alright :laugh: Please post the contents of your TextBox1 after pressing and releasing a single key.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Sascha Lefevre

No - not for a single key but for two different keys please, in sequence.

If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson

Lost User

i am not understanding : (((( can you set an example?... i guess the textbox1 is not affecting the MIDI playing!!! What is making the play its the "m.playMIDINote" function!!! The textbox1 is just for showing the data that is being sent from the MIDI Keyboard into the PC!