Fast Timer + Sequencer + Tempo Problem

[some1uk03]

I've got a small sequencer going on, but am facing a few issues with the Timer. I was happy to a certain degree for a while but now I want to tackle this again.

All these other sequencer apps like Cubase, Logic etc have smooth running playback systems where you can play the song and still do things in the background without affecting the playback in any way.
Whereas here with me, having 8 tracks or moving the form around, etc, pauses and hangs the timer.

KillTimer seems to run smoothly, but doesn't go below 1ms intervals.
QueryPerformanceCounter with a do/Loop is perfect in terms of accuracy & Tempo etc, but causes the hang.

So, can anyone figure out how to have a smooth timer going on without being interrupted ?

Attached is my small project below.

Timer.zip

[baka]

that is why I use borderstyle=0 and use my own method to move around the form.

[The trick]

Never ever use timers in such scenarios, you should synchronize your UI using your sound events like when you fill a buffer.

[some1uk03]

that is why I use borderstyle=0 and use my own method to move around the form.

I'm currently using (releaseCapture / sendmessage)
What's your method?

Never ever use timers in such scenarios, you should synchronize your UI using your sound events like when you fill a buffer.

I'm not quite sure what you mean by that.

I have a an array() of events with Ticks that need triggering at certain points.
That's why I have a timer on a loop checking for matching Ticks to raise the PLAY event.

[LeandroA]

the modTimer uses a loop with a Doevents, that makes it stop you can check it with this simple code

Option Explicit
Private Declare Function ReleaseCapture Lib "user32" () As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
   
Dim bFlag As Boolean
Dim Counter As Long

Private Sub Form_Load()
    Me.Show
    bFlag = True
    Do While bFlag
        Counter = Counter + 1
        Cls
        Me.Print Counter
        DoEvents
    Loop

End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Call ReleaseCapture
    Call SendMessage(Me.hwnd, &H112, &HF012&, 0)
End Sub

Private Sub Form_Unload(Cancel As Integer)
    bFlag = False
End Sub

[The trick]

I have a an array() of events with Ticks that need triggering at certain points.

For events you should use WaitForSingleObject or something like Waiter. But im sure you select a wrong way because you should have a single buffer which you should track. When you fill this buffer with the data you check your events. If the events has been triggered you just add the samples of your new audio so you get the resolution with your sample rate frequency.

[some1uk03]

I think you're presuming that I'm playing a single .wav file in a buffer and I'm seeking a way to find play positioning. That's not the scenario.

Think of musical notes in an array.
sNotes(0).start = 50 (ticks)
sNotes(1).start = 100 (ticks)
sNotes(2).start = 122 (ticks)
sNotes(4).start = 240 (ticks)

So the Timer goes through the sNotes array on each increment.
If timerTicks = sNotes(loop).start then PLAY

[The trick]

I think you're presuming that I'm playing a single .wav file in a buffer and I'm seeking a way to find play positioning. That's not the scenario.

Think of musical notes in an array.
sNotes(0).start = 50 (ticks)
sNotes(1).start = 100 (ticks)
sNotes(2).start = 122 (ticks)
sNotes(4).start = 240 (ticks)

So the Timer goes through the sNotes array on each increment.
If timerTicks = sNotes(loop).start then PLAY

I'm just talking about this scenario.

[some1uk03]

I'm having difficulty understanding your model.
Either way it needs some form of a Timer to know the elapsed time in order to trigger the next event.

Even instead of a LOOP/TIMER we calculate the different between currentTick vs Next Tick Event, you need a form of a timer to calculate that difference.


I'm currently exploring the WAITER class to see if it handles ticks (as opposed to ms), which may be another option.

[baka]

theres many different methods to use instead of releasecapture. the same is if u hold mousedown on titlebar if using borderstyle>0
my method is just "when u press mouse down" it will store x/y position of the mouse relative to form left/top.
when mouse-move the form is "locked" so it know the -x/-y that I got from mouse down. and mouse-up, it will "release it".
now the form moves together with mouse and everything that is happening inside the form is showing. no delay/freeze.

[The trick]

See this small sequencer example:

Option Explicit

Private Declare Sub memcpy Lib "kernel32" _
                    Alias "RtlMoveMemory" ( _
                    ByRef Destination As Any, _
                    ByRef Source As Any, _
                    ByVal Length As Long)
                    
Private Const NUM_OF_CHANNELS   As Long = 4
Private Const SAMPLE_RATE       As Long = 44100

Private Type TSound
    lSamples    As Long
    iValues()   As Integer
End Type

Private WithEvents m_cPlayer    As clsTrickSound2
Private m_tSounds()             As TSound
Private m_fTempo                As Single

Private Sub Form_Load()
    Dim lChIndex    As Long
    Dim lQIndex     As Long
    Dim lIndex      As Long
    
    For lChIndex = 0 To NUM_OF_CHANNELS - 1
        For lQIndex = 0 To 15
        
            If lIndex Then
                Load chkKey(lIndex)
            End If
                
            With chkKey(lIndex)
                .Move lQIndex * .Width + fraTempo.Left, lChIndex * .Height + fraTempo.Top * 2 + fraTempo.Height
                .Visible = True
            End With
            
            lIndex = lIndex + 1
            
        Next
    Next
    
    Me.Width = (Me.Width - Me.ScaleWidth) + 16 * chkKey(0).Width + fraTempo.Left * 2
    Me.Height = (Me.Height - Me.ScaleHeight) + NUM_OF_CHANNELS * chkKey(0).Height + fraTempo.Top * 3 + fraTempo.Height
    
    fraTempo.Width = Me.ScaleWidth - fraTempo.Left * 2
    sldTempo.Move sldTempo.Left, sldTempo.Top, fraTempo.Width - sldTempo.Left * 2
    
    sldTempo_Change
    
    ReDim m_tSounds(NUM_OF_CHANNELS - 1)
    ReDim m_tChannel(NUM_OF_CHANNELS - 1)
    
    m_tSounds(0) = LoadSound(App.Path & "\kick.snd")
    m_tSounds(1) = LoadSound(App.Path & "\snare.snd")
    m_tSounds(2) = LoadSound(App.Path & "\hi-hat.snd")
    m_tSounds(3) = LoadSound(App.Path & "\crash.snd")
    
    Set m_cPlayer = New clsTrickSound2
    
    m_cPlayer.InitPlayback 2, SAMPLE_RATE, 16, (SAMPLE_RATE * 2 * 0.05) And -2
    m_cPlayer.StartProcess
    
End Sub

Private Sub m_cPlayer_NewData( _
            ByVal DataPtr As Long, _
            ByVal CountBytes As Long)
    Static s_lBlock                         As Long
    Static s_lChIdx(NUM_OF_CHANNELS - 1)    As Long
    Static s_bChState(NUM_OF_CHANNELS - 1)  As Boolean
    Static s_iData()                        As Integer
    Static s_bDataInitialized               As Boolean
    Static s_lPrevUIBlock                   As Long
    
    Dim lBIndex     As Long
    Dim lKIndex     As Long
    Dim lChIndex    As Long
    Dim lBlocks     As Long
    Dim lBlkPerQ    As Long
    Dim lSampleL    As Long
    Dim lSampleR    As Long
    Dim lPbOffset   As Long
    
    If Not s_bDataInitialized Then
        ReDim s_iData(CountBytes \ 2 - 1)
        s_bDataInitialized = True
    End If
    
    lBlocks = CountBytes \ 4
    lBlkPerQ = 240 / m_fTempo * SAMPLE_RATE / 16
    
    For lBIndex = 0 To lBlocks - 1
        
        lSampleL = 0:   lSampleR = 0
        
        If (s_lBlock Mod lBlkPerQ) = 0 Then

            lKIndex = s_lBlock \ lBlkPerQ
            
            If lKIndex >= 16 Then
                lKIndex = 0
                s_lBlock = 0
            End If
            
            For lChIndex = 0 To NUM_OF_CHANNELS - 1
            
                If chkKey(lChIndex * 16 + lKIndex).value Then
                    s_bChState(lChIndex) = True
                    s_lChIdx(lChIndex) = 0
                End If
                
            Next
            
        End If
        
        For lChIndex = 0 To NUM_OF_CHANNELS - 1
            If s_bChState(lChIndex) Then
                
                lSampleL = lSampleL + m_tSounds(lChIndex).iValues(s_lChIdx(lChIndex))
                lSampleR = lSampleR + m_tSounds(lChIndex).iValues(s_lChIdx(lChIndex) + 1)
                
                s_lChIdx(lChIndex) = s_lChIdx(lChIndex) + 2
                
                If s_lChIdx(lChIndex) >= m_tSounds(lChIndex).lSamples Then
                    s_bChState(lChIndex) = False
                End If
                
            End If
        Next
        
        If lSampleL > 32767 Then
            lSampleL = 32767
        ElseIf lSampleL < -32768 Then
            lSampleL = -32768
        End If
        
        If lSampleR > 32767 Then
            lSampleR = 32767
        ElseIf lSampleR < -32768 Then
            lSampleR = -32768
        End If
        
        s_iData(lBIndex * 2) = lSampleL
        s_iData(lBIndex * 2 + 1) = lSampleR
        
        s_lBlock = s_lBlock + 1
        
    Next
    
    ' // Update visual
    lPbOffset = (m_cPlayer.BufferLengthSamples * m_cPlayer.BuffersCount + CountBytes \ 2) \ 2
    
    lKIndex = ((s_lBlock - lPbOffset) \ lBlkPerQ) Mod 16
    
    If lKIndex < 0 Then
        lKIndex = 16 + lKIndex
    End If
    
    For lChIndex = 0 To NUM_OF_CHANNELS - 1
    
        chkKey(lChIndex * 16 + lKIndex).BackColor = vbRed
        
        If s_lPrevUIBlock <> lKIndex Then
            chkKey(lChIndex * 16 + s_lPrevUIBlock).BackColor = vbWhite
        End If
        
    Next
    
    s_lPrevUIBlock = lKIndex

    memcpy ByVal DataPtr, s_iData(0), (UBound(s_iData) + 1) * 2
    
End Sub

Private Function LoadSound( _
                 ByRef sPath As String) As TSound
    Dim tRet    As TSound
    Dim iFNum   As Integer
    Dim lSize   As Long
    
    iFNum = FreeFile
    
    Open sPath For Binary As iFNum
    
    lSize = LOF(iFNum)
    
    If lSize Then
        ReDim tRet.iValues(lSize \ 2)
        Get iFNum, , tRet.iValues
    End If
    
    tRet.lSamples = lSize \ 2
    
    Close iFNum
    
    LoadSound = tRet
    
End Function

Private Sub sldTempo_Change()
    m_fTempo = sldTempo.value
    fraTempo.Caption = "Tempo (" & CStr(m_fTempo) & " BPM)"
End Sub

Private Sub sldTempo_Scroll()
    sldTempo_Change
End Sub

It use this class for sound playback.

[some1uk03]

@TheTrick: Thank you for the example. I will take some time to analyse it tomorrow, but having a quick glance seems to be a very very different approach to what I currently have. And I'm not sure, I can go ahead and change my whole project to a totally different approach at this point of time.

Do you think there could be an alternative approach with the Timer methods I'm currently using ?

[The trick]

Do you think there could be an alternative approach with the Timer methods I'm currently using ?

As i already wrote you shouldn't use timers for this purpose because they are not accurate. If you don't need accurate time periods you could use multimedia timers but it'll require either high CPU loading or threading issues. Most of the DAW i know uses approach which i showed you so i would hihgly recommend you to change your architecture.

[Schmidt]

I'm currently using (releaseCapture / sendmessage)
What's your method?

I've recently posted a solution for that kind of blocking here:
https://www.vbforums.com/showthread....nd-a-solution)
(based on subclassing).

Olaf

[Mikle]

As an alternative to the timer, you can use a waiting cycle with synchronization by the exact QueryPerformancaCounter(). I attach an example of a simple metronome based on this principle, the Sleep() function in the example is not used for synchronization, but to reduce the load on the CPU while waiting for the next event.
I use this .tlb: https://www.vbforums.com/showthread....und&highlight=

[baka]

my recommendation is to follow The trick suggestions.
we can always do workarounds but in the end, when we implement experts solutions we notice the difference in quality.
so, even if this will require a startover it will reward u later.

[Schmidt]

If it is for "Midi-Notes only", then a normal Timer triggering the "Notes"
(with 15msec +-8msec interval) - seems entirely sufficient.

And due to the "slight imprecisions in timing" when triggering Notes,
it even sounds more like "natural playing"...
(less "mechanical" when compared to "msec-exact-outputs").

Olaf

[Mikle]

With the assistance of WinAPI commands, the accuracy of the system timer can be increased to 1 ms, then this is really enough for midi notes, but 16 ms is clearly not enough even for this.
But when mixing audio tracks, even 1 ms is very inaccurate, at a frequency of 500 Hz it will create an antiphase.