RAM usage increasing when reading frames from camera - vb.net

Question

I'm making some tests with AForge library. I'm trying to read data coming from my usb camera(frames). It works very nice but the only problem is the RAM. It leaks. It seems taht a frame takes ~30 KB but the used memory keeps increasing.
Here's my code:
Imports AForge
Imports AForge.Controls
Imports AForge.Video
Imports AForge.Video.DirectShow
Imports System.Threading
Imports System.IO
Imports System.Collections.Concurrent
Imports System.ComponentModel
Public Class Form1
Dim sources As New FilterInfoCollection(FilterCategory.VideoInputDevice)
Dim WithEvents device As VideoCaptureDevice
Dim count As Long, bit As Bitmap
Dim read As New Thread(AddressOf read_que)
Dim pic_que As New ConcurrentQueue(Of Bitmap)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For Each cam As FilterInfo In sources
ComboBox1.Items.Add(cam.Name)
Next
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
device = New VideoCaptureDevice(sources(ComboBox1.SelectedIndex).MonikerString)
AddHandler device.NewFrame, new Video.NewFrameEventHandler(AddressOf frame)
device.WaitForStop()
device.Start()
End Sub
Sub frame(obj As Object, args As NewFrameEventArgs)
If bit IsNot Nothing Then
bit.Dispose()
bit = Nothing
End If
bit = New Bitmap(args.Frame)
If PictureBox1.Image IsNot Nothing Then
PictureBox1.Invoke(New MethodInvoker(Sub() PictureBox1.Image.Dispose()))
End If
PictureBox1.Image =bit ' or ... = Imaging.Image.Clone(args.Frame)
End Sub
End Class
I tried even to put all the frames in a concurrent queue and then in a separate thread to read it(I posted the simplified version that seems to take the least ram memory).
But there's another problem (this is not that important): when I start the app the picturebox is blanck and the used ram is 16 MB (constant-so it doesn't work).
Only when I enter task manager and I press End Process(without actually closing it) it starts showing the frames. I thing it's GUI related(when I press the End Process maybe it fires an event that starts the frame-reading class?).
Only at random times it seems to work from the first time(it's true that it might be the camera's problem because it old and works only on XP so I had to use .NET Framework 4).
Where is the problem(the priority is the ram leakeage)?

Answer 1

Try using this:
Sub frame(obj As Object, args As NewFrameEventArgs)
If Me.InvokeRequired Then
Me.BeginInvoke(Sub() frame(obj, args))
Else
Dim oldImage = PictureBox1.Image
Dim bitmap = New Bitmap(args.Frame)
args.Frame.Dispose() 'Not sure if it has a Dispose
PictureBox1.Image = bitmap
If oldImage IsNot Nothing Then oldImage.Dispose()
End If
End Sub

Answer 2

Solved it. Thanks for all your help but I knew that my code was working(I used before a delegate to draw on picture box so it was thread-safe-the code I provided was "quick and dirty"). The problem was...the VM. I was testing the code on a VM. It works on a normal PC.
The code looks now like this:
Imports AForge
Imports AForge.Controls
Imports AForge.Video
Imports AForge.Video.DirectShow
Imports System.Threading
Imports System.IO
Imports System.Collections.Concurrent
Imports System.ComponentModel
Public Class Form1
Dim sources As New FilterInfoCollection(FilterCategory.VideoInputDevice)
Dim device As VideoCaptureDevice
Delegate Sub lp(ByRef pic As Bitmap)
Delegate Sub lpp(nr As Integer, nr2 As Integer)
Delegate Sub slp()
Dim count As Long, bit As Bitmap
Dim read As New Thread(AddressOf read_que)
Dim pic_que As New ConcurrentQueue(Of Bitmap)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For Each cam As FilterInfo In sources
ComboBox1.Items.Add(cam.Name)
Next
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
device = New VideoCaptureDevice(sources(ComboBox1.SelectedIndex).MonikerString)
AddHandler device.NewFrame, new Video.NewFrameEventHandler(AddressOf frame)
'device.WaitForStop()
device.Start()
'read.IsBackground = True
'read.Start()
End Sub
Sub frame(obj As Object, args As NewFrameEventArgs)
'If bit IsNot Nothing Then
' bit.Dispose()
' bit = Nothing
'End If
'bit = New Bitmap(args.Frame)
If PictureBox1.Image IsNot Nothing Then
PictureBox1.Invoke(New MethodInvoker(Sub() PictureBox1.Image.Dispose()))
End If
PictureBox1.Invoke(New MethodInvoker(Sub() PictureBox1.Image = Imaging.Image.Clone(args.Frame))) 'Imaging.Image.Clone(args.Frame) ' or ...=bit
End Sub
End Class